Tuesday, December 31, 2013

Winter weather chances to start 2014 -- and a sincere word of thanks

Since you're asking, and we can't let a forecast of snow go by without a blog, here's what we have to say about it.  (Instead of model graphics, we're only showing memes in this blog since it's our last of 2013.)


Rain Wednesday night will taper off as temps fall and could end as flurries or a light snow shower early Thursday morning. We aren't worried about it and you shouldn't be either.  But we're in Memphis and it could hit during rush hour.  So go ahead and freak out.  Prior to that, a great start to 2014 with temps in the 50s tomorrow afternoon.

Behind the barely-worth-mentioning snow Thursday morning, it's going to be cold. Temperatures could stay below freezing all day Thursday then fall to 19 Friday morning. That would be the coldest we've seen in the Bluff City since February 2011.  And it's not over... we'll only see the mid 30s on Friday, then some moderation before yet another Arctic blast arrives late Sunday.


Sunday's weather had us scratching our collective heads in the weather world for a day or two until today. That's when the European model, which previously locked us in the deep freezer Sunday through early next week, cracked the door open just a bit. However, we'll definitely still feel the effects of the North Pole basically relocating south. Our low of 19 Friday morning will likely not be the coldest we see in the first week of 2014. Look for 20s for highs in some areas on Tuesday.

The snow chance on Sunday is just a little more interesting than Thursday. Timing of the cold air will be key.  Previously I expected it to be early in the day. Now it appears it will be later, which will have a definite (negative) effect on possible snow totals. We'll talk more about that in another post as it gets closer. For now, Kroger stock is up only slightly.  Click here for the slightly-more-official MWN Forecast.


Finally, and perhaps more importantly, we want to wish all of our followers old and new a happy, healthy, safe, and prosperous 2014!!  We've are grateful for your support in 2013.  It's been a banner year.  So as the sun sets on 2013, we THANK YOU for your comments (even those that demand that we stick to weather tweets), notes of encouragement, and sincere thanks.  We're blessed to do what we do, to truly LOVE what we do, and have people that appreciate it.


Signing off for 2013 --

Erik Proseus
MWN Meteorologist

Patrick Luckett & William Churchill
Aspiring meteorologists & MWN Interns

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Sunday, December 29, 2013

Updated: Recap of tornado and damaging wind event from December 21

For a number of days leading up to yesterday, the potential for severe weather was apparent and in most forecasts.  As the week went on, the concern for tornado potential increased as the high magnitude of wind shear was better realized.  The main deterrent was going to be the degree of instability.

Overview

By Friday, the Storm Prediction Center had issued a Day 2 Moderate Risk forecast, which continued into the Saturday morning forecast.  However, as showers over east AR inched towards the Mississippi River, it became clear that instability would not be quite as high and the Moderate Risk was downgraded to a Slight Risk for west TN and east AR near the Mississippi River.  However, sufficient instability was present to produce severe storms resulting in damaging wind of up to 80 mph and five tornado touchdowns in or near the metro, as well as a couple of small hail storms.

Below is a map showing damage reports from the metro region. Click here for a complete listing from NWS-Memphis and details on each event. (Note that the four Mississippi tornado confirmations were made after the map below was created.)


A total of 11 Tornado Warnings, 34 Severe Thunderstorm Warnings, and 15 Flash Flood Warnings were issued by NWS-Memphis. Maps of the warnings issued during the day and evening are shown below.  Kudos to the forecasters at the Agricenter for staying on top of storms moving at up to 70 mph!

All Tornado, Severe Thunderstorm, and Flash Flood Warnings issued by NWS-Memphis on 12/21/13

All Severe Thunderstorm Warnings issued by NWS-Memphis on 12/21/13

All Tornado Warnings issued by NWS-Memphis on 12/21/13

Flooding

The other chief concern was going to be flooding, especially across northeast AR where 4-6" was forecast.  The rest of the metro was expected to get 1.5-2".  This is nearly exactly what happened, as can be seen in the graphic below.  MWN picked up 2.15" of rain Friday and Saturday, while Memphis International Airport received 2.10" for a two-day total.

Rainfall totals from 7am Saturday through 7am Sunday.

Tornado Summary

The first tornado confirmation by the NWS was from Hughes, AR.  An EF-2 tornado with maximum wind of 130 mph killed one and injured three, as well as destroying a few mobile homes and damaging other structures.  The path length was 15.6 miles and width was 300 yards.

Hughes, AR tornado damage. Photo courtesy Austin Lewis, Local 24 News, Memphis.
The second tornado occurred near Clarksdale, MS where an EF-2 with 120 mph wind traveled 10.4 miles, killing one and injuring another.  Major damage occurred at a mobile home where the fatality occurred and Coahoma County High School and an elementary school also sustained damage.

The third tornado touched down southwest of Senatobia, MS in Tate County, traveling 6.2 miles and peaking at EF-1 strength or 100 mph.  There were no fatalities and a handful of homes sustained damage, along with trees being uprooted.

The fourth confirmed tornado occurred in southern Tunica County, MS, producing 90-100 mph (EF-1) wind and traveling 2.7 miles. There were no fatalities or injuries. Damage included a church that was pushed at least ten feet off its foundation, multiple homes damaged, a mobile home rolled, large power lines snapped, and some debris thrown more than a mile.

Finally, a fifth tornado was confirmed near Independence, MS in Tate County. An EF-0 with 65-80 mph was on the ground for approximately 3/4 miles, snapping and uprooting trees, downing power lines, and causing minor roof damage to multiple homes and a church.

Below is the final statement from the NWS on the five tornadoes.

PUBLIC INFORMATION STATEMENT...CORRECTED
NATIONAL WEATHER SERVICE MEMPHIS TN
745 PM CST TUE DEC 24 2013

...NWS DAMAGE SURVEY FOR 12/21/13 TORNADO EVENT...

ADDED CONFIRMED TORNADOES IN TUNICA AND TATE COUNTIES

.TORNADO NEAR HUGHES ARKANSAS...
...START TIME CORRECTED...

RATING: EF2
PEAK WIND /ESTIMATED/:130 MPH
PEAK LENGTH /STATUTE/: 15.6 MILES
PATH WIDTH /MAXIMUM/: 300 YARDS
FATALITIES: 1
INJURIES: 3

START DATE: 12/21/13
START TIME: 0313 PM CST
START LOCATION: 6 MILES SOUTHWEST/HUGHES/ARKANSAS
START LAT/LON: 34.907/-90.559

END DATE: 12/21/13
END TIME: 0329 PM CST
END LOCATION: 1 MILE NORTHWEST OF TARSUS
END LAT/LON: 35.099/-90.415

SURVEY SUMMARY:
NEAR HUGHES 3 MOBILE HOMES WERE DESTROYED. ROOF DAMAGE OCCURRED TO
TWO HOMES AND A BARN WAS DAMAGED. A NUMBER OF IRRIGATION PIVOTS
WERE OVERTURNED. NEAR WILDWOOD A METAL SHED WAS DESTROYED. POWER
LINES WERE ALSO DAMAGED ALONG THE PATH.


.TORNADO NEAR RENA LARA MISSISSIPPI...

RATING: EF2
PEAK WIND /ESTIMATED/: 120 MPH
PEAK LENGTH /STATUTE/: 10.4 MILES
PATH WIDTH /MAXIMUM/: 300 YARDS
FATALITIES: 1
INJURIES: AT LEAST 1

START DATE: 12/21/13
START TIME: 519 PM CST
START LOCATION: RENA LARA MISSISSIPPI
START LAT/LON: 34.149/-90.767

END DATE: 12/21/13
END TIME: 528 PM CST
END LOCATION: CLARKSDALE MISSISSIPPI
END LAT/LON: 34.210/-90.607

SURVEY SUMMARY:

MAJOR DAMAGE TO MOBILE HOME WHERE FATALITY OCCURRED. COMPLETE
DESTRUCTION OF 2 LARGE GARAGE SHEDS. 2 FOOTBALL LIGHT POLES BENT AND
DESTROYED AT COAHOMA COUNTY HIGH SCHOOL. ROOF AND WINDOW DAMAGE TO
ELEMENTARY SCHOOL ON BOBO-SHARARD ROAD. SEVERAL HOMES WITH MINOR TO
SIGNIFICANT ROOF DAMAGE TO 4 HOMES ON COUNTY ROAD 332. SEVERAL TREES
UPROOTED OR SNAPPED OFF ALONG THE PATH OF THE TORNADO.


.TORNADO NEAR SENATOBIA MISSISSIPPI...

RATING: EF1
PEAK WIND /ESTIMATED/: 100 MPH
PEAK LENGTH /STATUTE/: 6.2 MILES
PATH WIDTH /MAXIMUM/: 200 YARDS
FATALITIES: NONE
INJURIES: UNKNOWN

START DATE: 12/21/13
START TIME: 557 PM CST
START LOCATION: 10.1 MILES SW SENATOBIA
                     /COUNTY ROAD 310 WEST OF COMO/
START LAT/LON: 34.519/-90.094

END DATE: 12/21/13
END TIME: 602 PM CST
END LOCATION: 4.3 MILES SW SENATOBIA /HAMILTON HILL ROAD/
END LAT/LON: 34.570/-90.005

SURVEY SUMMARY:

4 HOMES RECEIVED ROOF DAMAGE WITH A 2 STORY HOME RECEIVING DAMAGE
ASSOCIATED WITH THE COVERED PORCH BEING LIFTED AND DEPOSITED ONTO
ROOF OF GARAGE. SEVERAL TREES UPROOTED OR SNAPPED OFF NEARBY AT
THE STARTING LOCATION OF THE TORNADO.


.TORNADO IN SOUTHERN TUNICA COUNTY...

RATING: EF1
PEAK WIND /ESTIMATED/: 90-100 MPH
PEAK LENGTH /STATUTE/: 2.7 MILES
PATH WIDTH /MAXIMUM/: 200 YARDS
FATALITIES: NONE
INJURIES: NONE

START DATE: 12/21/13
START TIME: 540 PM CST
START LOCATION: FLEA HARBOR ROAD OFF OF US HIGHWAY 61
START LAT/LON: 34.4465/-90.4171

END DATE: 12/21/13
END TIME: 544 PM CST
END LOCATION: SIX MILE LAKE ROAD NEAR BENNETT RD
END LAT/LON: 34.4665/-90.3769

SURVEY SUMMARY:

CHURCH PUSHED OFF ITS FOUNDATION BY 10 FEET OR MORE...MULTIPLE HOMES
DAMAGED ON FLEA HARBOR ROAD. TRAILER ROLLED AND DEBRIS THROWN FOR AT
LEAST A MILE FROM HOMES. POWERLINES SNAPPED...WITH LARGE POWERLINES
SNAPPED ON SIX MILE LAKE ROAD.


.TORNADO NEAR INDEPENDENCE MISSISSIPPI...

RATING: EF0
PEAK WIND /ESTIMATED/: 65-80 MPH
PEAK LENGTH /STATUTE/: .75 MILES
PATH WIDTH /MAXIMUM/: 100 YARDS
FATALITIES: NONE
INJURIES: UNKNOWN

START DATE: 12/21/13
START TIME: 613 PM CST
START LOCATION: NEAR MAYS AND WAKEFIELD ROAD
START LAT/LON: 34.7412/-89.7413

END DATE: 12/21/13
END TIME: 617 PM CST
END LOCATION: ALONG MAYS ROAD
END LAT/LON: 34.7454/-89.7296

SURVEY SUMMARY:

MULTIPLE TREES SNAPPED AND UPROOTED. MANY HOMES WITH MINOR ROOF
DAMAGE. CHURCH WITH MINOR ROOF DAMAGE. POWERLINES DOWNED.

$$

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Saturday, December 28, 2013

Showers tonight, possible light snow Sunday night, and a cool Liberty Bowl

We hope everyone had a great Christmas week, got to spend time with friends and family, and got everything they wanted from Santa! Besides cold conditions, not a bad weather week overall. We were pleased to be able to spend all of Christmas Day with family without once looking at a computer model or posting on social media.  Thanks for allowing us a rare day off! Another holiday-interrupted week is ahead, but weekend weather will make for an interesting transition into New Year's week.

Clouds have already infiltrated Mid-South skies ahead of a developing low pressure area in the western Gulf of Mexico. This low will lift through the southeast U.S. tonight into Sunday wrapping precipitation around the backside of it and into mainly eastern parts of the Mid-South.  The Memphis metro figured to be on the back side of the precipitation shield overnight, with heavy rain well to our southeast and nearly dry conditions just across the river in AR. The best chances of light rain will be overnight tonight with up to 0.10" possible by Sunday morning. Temperatures will be sufficiently warm to keep the precip all rain.

GFS forecast precipitation amounts through Sunday evening. About 0.10" is possible in the metro, though flooding will be a concern over parts of the southeast with totals near 3".
Sunday we will be between the departing low to the east and an Arctic cold front approaching from the northwest, leading to a partly sunny day with seasonal temperatures and an increasing wind from the northwest by afternoon. In the wake of the cold front, a little left over moisture in the atmosphere could be squeezed out by very cold air, bringing a *small chance* of precipitation that could transition from light rain in the evening to flurries or light snow overnight Sunday night.

Models are split on whether we see anything measurable, but sprinkles or flurries are certainly possible. To be honest, this is not the type of pattern we usually see much in the way of precipitation from, especially anything accumulating, but it's worth mentioning.  A couple of model solutions (none are the official forecast!) are shown below. The NAM model has been the most aggressive, bringing a dusting of snow by Monday morning,  The GFS has consistently been dry, and the European has tended to side with the GFS, while the Canadians (snow-lovers that they are) lean towards the NAM.  IF we see anything, it won't be much (the Panic Meter sits with disinterest at a 1 out of 10), but the threat of it should keep schools closed for another week. :-)

Sat morning NAM model forecast of total snowfall through Monday. The NAM is the most aggressive with snow and produces a little more than a dusting across the metro Sunday night.

Last night's Canadian model forecasts about 0.10" of snow by Monday morning.

The European model hints at some light snow to our south, but thinks the metro gets nothing more than flurries. Of the 51 "members" of the ensemble system that make up the European, 8 give Memphis a dusting of snow. The rest are dry.  The GFS model is not represented in the model solutions above. It has consistently been dry. 

Monday will be just plain cold in the wake of the front. Lows in the mid 20s in the morning will have trouble getting any higher than the mid 30s (wind chills in the 20s) even with some afternoon sun, setting the stage for a very cold start to New Year's Eve day.  For those attending the Liberty Bowl Tuesday afternoon, dress warmly!  As the Bulldogs show Rice how football is played in the southeast (#HailState), temps will only top out in the mid 40s.  A cold but dry night is expected as 2014 is rung in Tuesday night.

Models disagree widely on the first few days of 2014, but that's a topic for another blog!  For the complete, and official, MWN Forecast, download the MWN mobile apps linked below or click here for the forecast on our mobile-ready website.

Erik Proseus
MWN Meteorologist

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Saturday, December 21, 2013

First Day of Winter, or Severe Weather Awareness Day? Be prepared today!

UPDATE - 12:40pm Saturday

A Tornado Watch has been issued for the Memphis metro until 8pm. SPC says that within the Tornado Watch area, there is a 50% chance of 2 or more tornadoes, 40% chance of an EF-2+ tornado, and a 60% chance of 10 or more high wind events.  Map (showing radar at issuance time) below.


UPDATE - 11:00am Saturday

The Storm Prediction Center has issued updated severe weather risk maps as of 10:30am.  The new overview map (below) has lowered the Moderate Risk to a Slight Risk for a portion of west TN (north of I-40 from Memphis to Jackson).  This is due to the presence of showers and more extensive cloud cover over this area, which is limiting instability.


What's instability?  Think of a pot of water on a stove.  The higher you turn up the heat, the warmer the water becomes. Turn down the heat a touch  and the water temp decreases.  Instability is the heat from the stove and the water is the atmosphere. In a primed atmosphere like we have today, it doesn't take a lot of heat (instability) to fire storms. A little less instability lowers the risk just a bit.

Even though instability is a bit lower, wind shear is still high so any storms that fire CAN still produce tornadoes. The chance of strong tornadoes still exists along and east of the Mississippi River in the latest SPC update. Damaging wind (up to 75 mph) is the primary threat. Timing has not changed from our original post below.  We expect a Tornado Watch to be issued in the next hour or two at most.  DO NOT LET YOU GUARD DOWN BECAUSE OF A MINOR CHANGE IN THE RISK AREA.


Originally issued 8:25am Saturday: 

The Storm Prediction Center, this morning, has expanded the Moderate Risk area - the most likely area to see severe storms - well to the northeast (see above), but the entire metro is still included.  The details of the storm system, including it's threats and timing, remain nearly the same as we posted in our blog on the topic late yesterday afternoon.

Below are the probability maps for today, showing the chance of tornadoes, severe wind (58 mph+), and large hail (1" or larger) within 25 miles of you. Click the graphic for a better view. According to SPC - the worldwide leaders in severe weather prediction - we have a 15% chance of a tornado (a few possibly strong), a  45% chance of severe wind (with potential for very damaging gusts of 75 mph+ in storms), and only a very small chance of hail.


Given the high probabilities of severe weather, SPC has issued a "Public Severe Weather Outlook" (below) to draw attention to a potential outbreak of severe storms.
PUBLIC SEVERE WEATHER OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0237 AM CST SAT DEC 21 2013

   ...SEVERE THUNDERSTORMS EXPECTED OVER PARTS OF THE LOWER MISSISSIPPI
   AND TENNESSEE VALLEYS TODAY THROUGH TONIGHT...

   The NWS Storm Prediction Center in Norman, Oklahoma is forecasting
   the development of a few strong tornadoes and swaths of damaging
   wind over parts of the lower Mississippi and Tennessee Valleys today
   through tonight.

   The areas most likely to experience this activity include:

          Northwest Alabama
          Central and Eastern Arkansas
          Western Kentucky
          Much of Louisiana
          Far Southeast Missouri
          Western and Northern Mississippi
          Western and Middle Tennessee

   Surrounding the greatest risk area, severe storms are also possible
   from eastern Texas and the central Gulf Coast region into the Ohio
   Valley.

   A potent jet stream disturbance now over west Texas will track
   northeast into Red River Valley later today, before accelerating
   northeast into the mid-Mississippi Valley tonight and early Sunday.

   Associated with this disturbance, an area of low pressure now
   forming over eastern Texas will become better organized as it moves
   northeast into southern Arkansas this afternoon, northwest Tennessee
   this evening, and the lower Ohio Valley early Sunday. 

   Ahead of the low, a broad flow of unseasonably warm and humid air
   will surge north from the western Gulf of Mexico into the lower
   Mississippi, the lower Tennessee, and the Ohio Valleys through early
   Sunday. 

   The increasing moisture and strong wind field that will accompany
   the jet stream impulse will create an environment favorable for
   bands of rotating thunderstorms capable of both potentially strong
   tornadoes and damaging wind over a broad swath extending from
   eastern Texas and southern Louisiana northeastward into the lower
   Mississippi and lower Tennessee Valleys.

   Although the severe weather threat is expected to be greatest this
   afternoon through early tonight over parts of Louisiana, Arkansas,
   Mississippi, and Tennessee, a more conditional risk for tornadoes
   and damaging winds will persist into early Sunday from the central
   Gulf Coast northeast into the mid-Ohio Valley.

   State and local emergency managers are monitoring this developing
   situation. Those in the threatened area are urged to review severe
   weather safety rules and to listen to radio, television, and NOAA
   Weather Radio for possible watches, warnings, and statements later
   today.

   ..Corfidi.. 12/21/2013
Today's scenario is not one to be taken lightly. The best chance for severe storms is after 2-3pm and the threat ends before midnight.  Tornado Watches will be issued.  If your safe place is not ready for you, get it ready!  You don't want to be cleaning it out when storms moving 60-70 mph are headed your way.  We can't guarantee you'll need it, but it's better to be safe than sorry.

The most likely severe weather scenario is a squall line, or perhaps a couple, containing very strong wind, however the tornado threat is not to be disregarded.  If a warning is issued, seek shelter immediately. Storms will be moving fast and wind of 60-70 mph or higher will pick up objects and can break the window you're staring out - even without a tornado.

We can't stress enough the need for multiple ways to receive severe weather warnings and paying attention to them today.  NOAA Weather Radio, local TV/radio, and smartphone apps are all good ways of receiving info. We strongly suggest getting StormWatch+ activated in your MemphisWeather.net mobile apps this morning and set your location(s) that you want warnings for. Then, don't silence your phone. it could be the best $8 you spend this Christmas season. Links to download are below.

Follows us on social media throughout the day for the latest (links below). We'll strive to keep you informed and safe, but it's up to you to know what to do if severe weather happens, and then to DO IT, if and when it becomes necessary. Stay safe.

Erik Proseus
MWN Meteorologist

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Friday, December 20, 2013

Severe weather possible Saturday - our thoughts on how it unfolds

As most people are aware by now, a risk of severe weather exists across area on Saturday.  All one has to do is step outside and feel the humidity, gusty south wind, and warm temperatures, then check the calendar, to know things aren't quite right in the atmosphere!

First, what we expect, for those who just want to know when it's going to rain and how bad it's going to get!

Tonight: As the MWN Forecast indicates, showers and thunderstorms are expected overnight tonight with unseasonably mild and breezy conditions.  The precipitation is expected to move in after 9pm and last intermittently throughout the night. No severe weather will occur tonight, though a few rounds of thunder are likely.

Saturday: A break in the precipitation will likely occur in the immediate metro during a chunk of the morning Saturday with rain and storms continuing to our northwest in AR.  No promises on the Ugly Sweater Run in the morning however! This will allow temperatures to climb to near-record levels in the mid 70s by noon.  By late morning or early afternoon, we expect scattered storms to again develop over the area, fueled by the rising morning temps. The severe weather risk with these cells increases as the afternoon goes along.  By mid to late afternoon, the storms should start organizing into waves or clusters of storms, perhaps with a "main round" of storms, or squall line, by late afternoon to early evening. These afternoon storms will pose a damaging wind threat, as well as a tornado threat.  In addition, outside of storms, it will be very windy during the day Saturday with gusts to 40-45 mph possible.  As my friend David in Nashville said, loosen any objects in your yard that you don't want to keep!

Below is a loop of one high-resolution model's IDEA on how storms will play out overnight tonight and through tomorrow evening. This is NOT a forecast, just a possibility. We wouldn't show it though if we didn't like the general idea it renders.

video

Finally, it should be noted that tomorrow's storms (due to the wind pushing them) will be moving at 50-60 mph.  If a warning is issued for your area, don't wait to see what happens - take action! At that speed, you don't have time to think about it or go look for the storm.  It could be on you before you know it.

A Moderate Risk of severe storms exists Saturday for the Memphis metro and points southwest.
Saturday night: By evening, or behind the first "main line" of storms, additional rainfall is a good bet and models are hinting at another fairly substantial line of storms during the late evening or early overnight hours.  Damaging wind will again be possible and a tornado can't be ruled out.  We expect all precipitation to move east of the metro between 10pm-midnight.  When all is said and done, we should see rainfall totals in the 1.5-2" range in the immediate metro. However, just to our northwest, in northeast AR and southeast MO, totals will be 4-6" with locally higher amounts, Flash Flood Watches are posted for these areas. After the rain ends tomorrow, we begin a stretch of cooler and dry weather that lasts through the Christmas holiday.

Rainfall totals from 6pm tonight through 6pm Sunday. 2" or so is expected in the metro while flash flooding is possible to our northwest where 4-6" is possible.
Turning a little more to the technical side... 

First, tornado threat: This event will be a typical "high shear, low instability" winter event.  While the winds at the surface and aloft are impressive and sufficient shear could be present for tornadoes (even strong ones), we'll have to watch closely if to see if instability can form. The best (or worst) case for this would be a dry morning with peaks of sunshine and temps in the mid 70s by noon.  Most other ingredients are in place, including surface low pressure that moves across AR (a classic transition season severe weather track).  If it can deepen enough, surface wind may back just enough to increase low-level helicity values sufficiently to produce tornadoes.  You'll note that this is not quite my usual spiel in which I completely downplay the tornado threat. Moderate risk areas on day 2 are not common and this setup is not "garden variety." While damaging wind (up to 70 mph) is a more likely threat due to low-level flow of 60+ knots as low as 2000-3000' above us tomorrow, enough shear could be present to spin up tornadoes. The most likely time for tornadoes is mid to late afternoon.

Second, flash flooding: we do not believe the flash flood threat is high in the immediate metro. Though precipitable water amounts are very high (over 1.5" tomorrow), the heaviest and most persistent precipitation will occur to our northwest along a stalled front that low pressure will move along and storms will be moving fast enough that we don't expect copious rainfall over a long period from any one storm or line.  However, all storms can and may produce torrential rainfall for brief periods, temporarily filling low-water crossings, ditches, etc.  If training storms develop, localized areas could see an inch or more of rain in a short period of time.

Preparedness
Plan ahead for what you'll do if you need to seek shelter quickly between early afternoon and late evening.  Where will you go and how will you know you need to take action?  Again, with storms moving at freeway speeds, you may not get much notice.  We HIGHLY recommend you get yourself an early Christmas present and purchase our MemphisWeather.net mobile app (only $0.99 for all of our great info, radar, forecast, etc.) and THEN activate StormWatch+ on the Alerts tab for about 1/4 the cost of a weather radio. A small one-time fee gets you personalized watch and warning information with alerts that will even wake you if you are sleeping - but only if YOU are in the path of the storm. Put the MWN meteorologist on your phone and fill the preparedness void with information you can count on!  Links to the apps are below.

We'll be providing rapid and timely updates throughout the day tomorrow on our social feeds below - which means you'll know exactly what to expect and when to expect it.  It's called social media nowcasting and you won't find it anywhere else in Memphis, with a focus on JUST the Memphis metro.

Erik Proseus
MWN Meteorologist

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Wednesday, December 18, 2013

Early look at weekend storms that follow unseasonably warm weather

First things first: NO, I don't know what a TORCON is or how it's calculated.  4?  8?  2?  I have no idea what's better or worse or what I should do if my area is assigned a certain number.  There's been no peer-reviewed research that explains how it is derived and there certainly is nothing that says, "if you are under a 5, do this."  I pay no attention to it, just like I have no idea what the name of snowflake was that fell on New York City yesterday.  Moving on...

So how 'bout those 70-degree temps in our forecast?!  If it were October, I'd be enjoying it much more.  But since it's mid-December, it must mean something on the opposite end of the spectrum is not too far behind!  An even bigger clue to that "something" resides in our forecast dewpoints, or available moisture in the low levels.  A number above 60 (pretty much anytime) indicates enough moisture to produce thunderstorms.  This time of year, 60 is abnormal (in fact, as I type, the dewpoint is 34, which means our atmosphere is going to moisten up in a hurry in the next 48 hours).

That moisture, which will setup our weekend weather system, will ride in on air coming straight out of the Gulf of Mexico on steady, becoming gusty, south wind starting tonight.  Basically, put low 70s temperatures on top of moisture-laden air, throw in a strong cold front and dynamic jet stream wind at multiple layers of the atmosphere, then mix in a low pressure system just to our west, and you have the ingredients for possible off-season severe thunderstorms.

So when's this all going down? Glad you asked.  We'll have one more nice day (tomorrow) and one more not-so-bad day (Friday) before things get interesting.  A few showers will likely break out by early Friday morning and part of the day Friday will be marked by scattered showers and maybe a rumble of thunder, though it will be far from a washout for you last minute shoppers.  We expect highs in the lower 70s with gusty south wind.  By Friday night, the cold front will bisect Arkansas from northeast to southwest and stall out as southwesterly upper level wind blows parallel to the front, effectively eliminating its "push" to the southeast. Rain and some thunder will be likely Friday night, especially along and north of I-40 it appears, as temperatures remain in the 60s all night.

By Saturday, low pressure will form along the front over northeast TX and travel along the front through Arkansas. This is where models differ, not so much on the details of the low as the amount of precipitation that forms ahead of it in the warm sector - or over east AR, west TN, and north MS - during the day Saturday.  This precip would be in the form of thunderstorms and, given the strong winds and shear in the atmosphere, some storms could be strong to severe.  The two most commonly used models in the mid-range (the American GFS and European ECMWF) have been pretty consistent in their own rights, but offer different solutions.  The ECMWF keeps the heaviest precip north of the metro Saturday, while the GFS drops heavy rain on the metro during the day Saturday.

GFS model (left panels) and European models (right panels) forecast precipitation for Saturday morning (top panels) and Saturday afternoon (bottom panels).  Note the GFS forecasts more precip Sat afternoon (bottom left) than the European (bottom right), which keeps heavy rain farther north.  Click for larger images.

Both models bring rain and thunderstorms through with a pre-frontal trough on Saturday night.  Thus, I feel Saturday during daylight hours is the biggest question mark at this point.  Late Friday night/early Saturday should be wet and Saturday night will definitely be wet.  All rain looks to exit quickly early Sunday morning as the trough moves east.

GFS model (left panels) and European models (right panels) forecast precipitation for Saturday evening (top panels) and after midnight Saturday night (bottom panels).  Note the GFS forecasts much more precip Sat evening (top left) than the European (top right), while the models are more similar after midnight. This leads to higher precip totals overall from the GFS.  Click for larger images.

As for severe weather potential, the Storm Prediction Center (which is the national authority on the topic) places the Mid-South and points southwest, back into central TX, in an elevated risk for severe storms on Saturday, mainly afternoon and nighttime hours.  This risk is equivalent to their "Slight Risks" in the shorter term.  For me, the biggest question concerns timing of precipitation and degree of instability.  In other words, will the precip will be confined to areas northwest of us during the day Saturday when instability would conceivably be at its peak?  Or will we get storms to form in the afternoon that could tap into the instability of daytime heating?  Also, will there be enough unstable air around after dark Saturday night when thunderstorms are more likely to result in severe weather?  At this point, it's too far out to say, but certainly bears watching.

SPC's Day 4 (Saturday) severe weather outlook - area that bears watching.

IF severe weather were to occur, the most likely times will be Saturday afternoon into the early overnight hours and the most likely form of severe weather will be damaging straight line wind and a few tornadoes.  This will be another so-called "high shear-low instability" event, in which sufficient wind energy and turning of the wind exists to support severe weather and a few tornadoes, but instability could be a limiting factor.  One thing we are fairly certain of is that there will be a lot of rain, perhaps up to 2-3", which could cause some flooding.  Keep your storm drains clean so water has somewhere to go.

GFS model (top) and European model (bottom) forecast rain totals through Sunday.  The GFS says about 2".  The European says 1.5-2".  Click for larger image.

Bottom line: "Off-season" severe weather events typically catch people off-guard due to the "it can't happen this time of year" mentality.  There are no guarantees that severe weather will occur, but several of the key ingredients will be in place. Think ahead to where your Saturday plans take you and how you will get severe weather information if it occurs.  We'll have more details as the day get closer.  Follow us on Facebook or Twitter for additional insight in the next few days and download the MWN mobile app, activating StormWatch+ while you're at it (via the Alerts tab in-app).  A "wake-me-up" style audio alert might come in handy if severe weather occurs late Saturday night.


Christmas Day P.S. -- If you're hoping for a white Christmas, it's time to set your sights on something else magical.  Sorry to dampen your Christmas spirit, but the answer is a resounding NO.  In fact, after this weekend system clears out, we'll be back to mostly sunny skies and seasonal temperatures for the first half of next week. Not bitter cold and not snow.

Erik Proseus
MWN Meteorologist

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Sunday, December 15, 2013

Peering into the crystal ball: Christmas Day 2013 weather outlook

Yesterday I posted on Facebook and Twitter that those who were interested in what the crystal ball said about Christmas Day weather in Memphis should tune in today.  I nearly jinxed myself - when I went to the computer this morning to update today's forecast, it wouldn't power up.  (Un)fortunately, I was able to resuscitate it this afternoon and now am obligated to bring you this update... unless a bolt of lightning from the blue strikes me down before I hit "Publish."

Ten-day forecasts are kind of like looking in the crystal ball, polishing it off, then looking again, shaking the Magic 8-Ball four or five times, then averaging it all together.  It's where the science of meteorology becomes the art of dancing around a forecast with just enough vague and non-committal wording to be able to say "I told you it would ____" no matter what happens! So here goes nothing...

First I point you to our updated "History of Christmas Day weather in Memphis" blog, which doesn't give you high hopes, other than that 3 of the past 4 years we've gotten VERY close to being snowy.  Then, I'll show you a video both entertaining and depressing at the same time, from Christmas Day 1963 - the only time this scene has played out in Memphis since records began:



Then, there's this:


So what about this year?  The long-range models (including the U.S.-based GFS, the European ECMWF, and Canadian GEM) just barely reach out to Christmas Day.  The last couple of runs of each of these don't provide much hope for scenes like that above.  Leading up to Christmas, a ridge of high pressure builds over the region this week, bringing warmer temperatures than we have seen in the past 10 days with highs reaching into the 60s by week's end.  Next weekend is where models begin to diverge, but all point to some sort of significant trough of low pressure and associated cold front pushing through between late Friday and early Sunday.  We expect a good deal of rain, likely some thunderstorms, and perhaps - if instability can be realized and dynamics are strong enough - a chance of severe storms.  Stay tuned.

Behind that trough early the following week (or basically around Christmas) is where we see multiple solutions from the models. The most recent GFS model run actually delays the weekend storm system (or perhaps I should say, gives us round 2 of a 1-2 punch) on Christmas Eve with very warm temps and storms, followed by a cold, dry Christmas Day. The rest of the models move the system out next weekend and settle high pressure in for the start of Christmas week with high temperatures averaging in the mid 40s to near 50 Christmas Eve, or roughly "near normal."  Most of these also point to a dry Christmas Day.

The Climate Prediction Center (part of the National Weather Service) has also been leaning towards next weekend's system moving out before Christmas with high pressure trailing.  Today's outlook for Christmas week gives us equal chances of above/below normal temperatures and a 50% chance of below normal precip with only a 17% chance of above normal precip.

The bottom line? I'll dance until the music stops to keep from making a call. :-) But typical December patterns and the timing of next weekend's system, as well as current forecast model data, point to a cool and dry Christmas Eve and Day.  Or just about what one would expect from any given Christmas in Memphis with an average high of 50 and average low of 33!  Those who know my propensity for playing down snow in Memphis until there is some degree of certainty won't be surprised by this outlook at all!  For those who prefer the glass-half-full approach,  I give you some classic Jim Carrey:



As any of our regular followers also know though, we promise to keep you updated as the number of shopping days diminishes and the magical day draws closer.

Erik Proseus
MWN Meteorologist

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History of Christmas Day weather in Memphis

As we enter the Christmas season and Mid-Southerners start wondering about the chances of a Bing Crosby Christmas, I thought this post would be a good one to re-visit and update.  So, what does history say about the chances of a white Christmas in the Bluff City?

Records that go back to 1889 show that Memphis had a measurable amount of snow on the 25th only once. That was in 1913 when 3.5 inches of snow fell on Christmas Day (1.4 inches was on the ground at 7:00 a.m. that day). Trace amounts (not enough to measure) fell on nine occasions - 1914, 1918, 1926, 1948, 1975, 1980, 1992, 2009, 2010, and most recently in 2012.  Last year, snow started at 11:53pm Christmas night [thus the "trace" of snow on Christmas Day] and by the next morning about 1" was on the ground.  We missed a White Christmas by a day!

There have been a few times when there was snow on the ground Christmas morning (from previous storms). The greatest was 1963 when 10 inches covered the city Christmas morning. 1962 and 2004 had 2 inches on the ground and there were patches of snow scattered around on Christmas morning in 1966.
The warmest temperature for Christmas Day was 76 degrees in 1889. 1983 had the coldest Christmas at zero (0) degrees.

While a Memphis snow is rare on Christmas Day, rain has fallen several times. Christmas was rainy 44 times in the last 136 years; sleet (or freezing rain) happened three times. The wettest Christmas Day came in 1987 when 4.24 inches of rain soaked Memphis.

Source: MemphisWeather.net and NWS-Memphis climate records. Image is "Graceland Christmas" by Thomas Kinkade, borrowed from artofthesouth.com.

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Wednesday, December 11, 2013

Cold weather to be followed by rain in time for the weekend

A cold weather pattern that featured average daily temperatures more than 10 degrees below normal for the past 6 days will continue into Friday, fortunately warming up just enough that our next chance of precipitation will be of the liquid variety!  A reinforcing shot of cool air is moving in tonight in the wake of a weak cold front today. That will send our low temperatures into the teens for parts of the area Thursday morning with a low near 20 in the city.

Widespread sub-freezing Thursday morning low temperatures from the GFS computer model

Another cool day is expected tomorrow with highs only topping out near 40 despite a sunny day. Thursday night lows will be a bit milder as southerly wind comes back and keeps us in the upper half of the 20s. The next rain event will arrive Friday afternoon as scattered showers, though temperatures will be warm enough for plain rain to fall in the metro.  (Cooler temperatures to our north could result in some light frozen precipitation for northeast AR and northwest TN.)

Scattered showers will move into the metro by 6pm Friday according to the European computer model

Rain is likely Friday night - in fact most of the precipitation we get with this system will occur between 6pm Friday and 6am Saturday. However, chance of light rain will linger into Saturday morning.  Lows Saturday morning will stay above freezing with no frozen precipitation expected locally.  By Saturday afternoon, most rain will be gone, but there could be a little drizzle under the cloud cover.

Showers departing by 6am Saturday, again from the European model
Sunshine returns to start next week. After a cold day Sunday, highs should rebound to "acceptable" levels (and which we won't haven't seen in a couple of weeks by then) in the 50s next week.  For complete forecast details, click here for desktop/tablet users or here for mobile phone users, or keep the forecast in your pocket with our mobile apps!

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Tuesday, December 10, 2013

November Climate Data and MWN Forecast Accuracy

The big story for November seemed to be intrusions of cold air on a few occasions, which left the area under Canadian high pressure and very cool temperatures. Overall temperatures and precipitation were well below average for the month, making for a cold and dry November.  The average temperature for meteorological fall (September-October-November) was near normal, but precipitation was below normal this year. For 2013 year-to-date, temperatures are averaging 63.9 degrees, or 0.8 degrees below normal.  Climate details for November can be found below.

Memphis International Airport, Memphis, TN

The average temperature for the month of November was 49.2 degrees, or 4.0 degrees below normal. The average high temperature was 59.0 degrees (3.6 degrees below normal) and the average low was 39.3 degrees (4.4 degrees above normal). The coolest temperature of the month was 21 degrees, reached on the 28th, while the highest temperature was 77 degrees on the 17th. There were nine days which saw low temperatures below 32 degrees and three days in which the high did not reach 40.  The high of 35 degrees on the 27th set a record (1938) for the coolest maximum temperature on record for that date. There were only six days in which the mean daily temperature was greater than 2 degrees above average.  For the period of meteorological fall, the average temperature was 64.0 degrees, which was 0.2 degrees below normal.

Precipitation for the month totaled 2.67", which was 2.82" below the average monthly rainfall for Memphis International. There were eight calendar days with measurable rainfall, but none which saw 1" or more.  Through November 30, annual precipitation at Memphis is 54.61", which is 6.67" above the 30-year average. During meteorological fall, precipitation totaled 8.66", which was 3.90" below normal.

The peak wind was 37 mph from the north on the 26th with an average wind speed for the month of 7.9 mph. The average relative humidity was 61 percent and average sky cover was 50 percent. Click here for a daily statistical recap for Memphis International Airport.

Cirrus Weather Solutions, Bartlett, TN

The average November temperature at Cirrus Weather Solutions was 47.5 degrees with a maximum of 77.3 degrees on the 17th and a minimum of 17.9 degrees on the 28th. There were 11 days with lows below 32 degrees and 3 days with highs below 40.  Monthly precipitation was lower than at the airport and measured 2.52" via the Cirrus automated gauge and 2.59" in a manual gauge used for the CoCoRaHS program. Maximum daily precipitation was 0.77" on the 17th on the automated gauge. For the year, the CoCoRaHS gauge at MWN has recorded 51.52" of precipitation, or just over 3" less than the airport. The measured peak wind gust was 22 mph on the 12th. Average relative humidity was 73%. Click here for a daily recap on MemphisWeather.net.

MWN Forecast Accuracy

For the month of November, the average temperature error in all MWN temperature forecasts was 2.08 degrees, lower than all available computer data models and the National Weather Service forecasts. MWN's forecasts extend out five periods (2.5 days, or roughly 60 hours). Over 66% of the MWN temperature forecasts for the month were within 2 degrees of the actual temperature. For dewpoint accuracy, the MWN forecast averaged 2.87 degrees error and fell within 2 degrees of the actual dewpoint over 51% of the time. Historical accuracy statistics can be found here.

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Monday, December 9, 2013

One last round of wintry weather possible tonight

UPDATED: The NWS issued a Winter Weather Advisory for one last round of potential wintry weather tonight for all but Crittenden and Tipton Counties. The text and a map of the affected area is below.


...WINTER WEATHER ADVISORY IN EFFECT FROM 6 PM THIS EVENING TO
3 AM CST TUESDAY...
 THE NATIONAL WEATHER SERVICE IN MEMPHIS HAS ISSUED A WINTER
WEATHER ADVISORY FOR FREEZING RAIN...SLEET AND SNOW... WHICH IS IN
EFFECT FROM 6 PM THIS EVENING TO 3 AM CST TUESDAY.
 * SNOW/SLEET/ICE ACCUMULATIONS...LESS THAN ONE TENTH INCH OF ICE
  ACCUMULATION. LIGHT SLEET AND SNOW ACCUMULATION.
 * TIMING...6 PM THIS EVENING UNTIL 3 AM CST TUESDAY
 * IMPACTS...BRIDGES AND OVERPASSES AND SECONDARY ROADS MAY BECOME SLIPPERY.
 PRECAUTIONARY/PREPAREDNESS ACTIONS...
 A WINTER WEATHER ADVISORY MEANS THAT PERIODS OF SNOW... SLEET... OR FREEZING RAIN WILL CAUSE TRAVEL DIFFICULTIES. BE PREPARED FOR SLIPPERY ROADS AND LIMITED VISIBILITIES... AND USE CAUTION WHILE DRIVING.

We expect that very light amounts of freezing rain and/or sleet and snow will be possible in northwest MS, as well as Shelby and Fayette Counties in TN tonight.  The most likely timing for light freezing rain and sleet is from 9pm to midnight with light sleet and snow possible from 11pm-3am. Very light precip and temps above freezing possible between 7-9pm. Temperatures will bottom out at 26 degrees during the period of precipitation, which could cause some slick spots on bridges and overpasses. Temperatures will climb above freezing Tuesday by 10-11am as the sun comes out.

Expected precipitation amounts overnight Monday night. Less than 0.10" is expected in the metro.
We will continue to monitor the progress of this system and update this blog post and our social media channels listed below as necessary.  Please watch for later forecast and statements and plan to exercise caution on elevated roadways after temperatures drop below freezing tonight.

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Saturday, December 7, 2013

Recapping yesterday's icy day and details on round 2 of wintry weather

Winter weather forecasts, at least from MWN and as far as we could tell most other local outlets, were pretty accurate for yesterday's winter weather system... with one critical exception: surface temperatures.

Rather than reaching the freezing mark by mid-morning (which they did) and then continuing to slowly fall, they stopped falling.  In fact, between periods of precipitation, there was actually a very slight rise to 32.5-33 degrees.  This made ALL the difference in the resultant amount of ice in the Memphis metro.  Instead of 0.25-0.50" of ice, which would have been likely had temps remained just below freezing, most places saw 0.10-0.20" and up to a quarter inch of sleet.  (Totals were MUCH higher just to our north where the air at the surface and aloft was colder.) Once precip tapered off and ended by late afternoon, the temperatures began falling, reaching the upper 20s by early evening.

Ice-covered trees in Bartlett Friday afternoon

The WXLIVE! weather station at MWN, covered in ice

The bottom line: one or two degrees of error on the forecast resulted in half or less the predicted ice, better road conditions that anticipated, and thankfully many less power outages. MLGW reached a peak somewhere above 8000 outages Friday afternoon and had nearly 100% restored by early Saturday morning. Kudos!  I won't say that any cancellations or postponements were for naught - the forecast and expected impacts were based on what we knew going into the event.  MWN picked up 0.60" of liquid (melted) precip after the temperature first hit 32 at 8:15 Friday morning. We were basically 1 degree from having a completely different scenario by last evening.



What's Next?

Looking ahead, we promised another round of wintry weather and that is still in play.  The NWS has issued Winter Weather Advisories for the entire area for the overnight hours tonight, ending at 6am Sunday.  Though precipitation amounts are not expected to be as high with the next round, there are a couple of key differences. Surface temperatures (at least overnight into tomorrow morning) will not be hugging the freezing mark - they'll start in the upper 20s.  In addition, very little melting today will mean trees and power lines START with minor ice accumulations, so anything additional will mean extra ice weight. One tenth of an inch to start and another one to two tenths falling totals a quarter inch of ice - which is Ice Storm Warning criteria.

Winter Weather Advisory posted for a large part of the area Saturday night until 6am Sunday

Forecast

As for what to expect, I've just hinted at it, but temperatures will not reach freezing today as clouds thicken ahead of tonight's storm and ice remains around the area. Light precipitation will start again tonight after 8pm, and maybe as late as midnight, continuing off and on overnight with light precip amounts expected. Most precipitation should taper off shortly after sunrise Sunday with 0.10-0.20" of an inch of freezing rain and minor sleet accumulation expected. Temperatures then rise above freezing by noon Sunday before another small round of precipitation moves through late in the day Sunday. I expect this late day light rain stay liquid with temps in the mid 30s.  For a complete forecast, including even COLDER temperatures in the week ahead, click here or check out our mobile apps (links below).

Impacts

So, while this does not appear to be a major event, additional power outages could result from the cumulative effects of icing (8000+ lost power with about the same amount of ice yesterday). There will also be less wind to dry the streets and they are starting off much colder than yesterday. I expect we could see some slick bridges and overpasses again late tonight and Sunday morning until temps rise above freezing. More trees branches will likely fall, especially those weakened by yesterday's storm.  If you have plans in the morning, be cautious.  If you don't have to go out early, things should improve by mid-day to early afternoon considerably.

Follow our social accounts below for the latest and greatest on round 2 of our early season winter blast!

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Thursday, December 5, 2013

FAQ on this weekend's winter weather

Wow, we've been getting a ton of questions regarding tomorrow's ice storm forecast. And with all the focus on tomorrow, most people seem to be overlooking round 2 on Saturday night. So, let's answer some of the most frequently asked questions.

1.  When is the ice going to start and how much will we get?

This varies a bit depending on where you are in the metro. The rain to freezing rain transition will occur from northwest to southeast.  Thus, Crittenden and Tipton Counties will transition first, probably between 3-6am; Shelby, Fayette, DeSoto, and Tunica Counties will probably transition between 7-10am; Tate and Marshall Counties between 10am-1pm.  Transition time will also affect total ice accumulations, as earlier transition will mean more time below freezing and likely higher amounts.  For most of the metro, though we expect average amounts to be around 1/2" of ice - perhaps a little more to the northwest and maybe a quarter inch over northwest MS.  All precip should come to an end by earlier evening, with the last few hours possibly seeing a little sleet or snow flurries.

2.  Are you sure this won't turn out to be one of "those" events where it goes by to our north/south?  What about the bluffs and Pyramid?

Confidence is high that the entire metro will see Ice Storm criteria met (0.25" of ice). While exact transition times and amounts may vary, this is not an event that will miss the metro.  It's been consistently forecast by the computer models for 5-6 days now. The bluffs will have no effect on this storm (or any other one for that matter).  The Pyramid has lost it's superpowers since the move of the pharaoh to the University of Memphis.

3.  What kind of impacts could we have from that much ice?

The main effects will be on trees and power lines, as well as elevated roads, bridges, and overpasses.  The weight of the ice will likely be enough to snap tree branches by afternoon (especially when combined with a 20-25 mph wind), which could fall on power lines weighted by ice.  Some power lines will also succumb to the ice by themselves.  The NWS is using an experimental "Ice Storm Index" this winter and it places the metro in the range of a category 2-3 (out of 5) in the southeast metro to a 3-4 in the northwest metro.  The indicates that a combination of expected ice and wind could cause numerous utility interruptions, some of which could be prolonged (up to 5-10 days), and some damage to main feeder lines.


As for road travel, any road that has air flowing beneath it will be subject to freezing up early on after the ice begins.  It just doesn't take more than a few hundredths of an inch of ice to make a skating rink on a bridge or overpass.  Avoid known danger spots: most of 385/Nonconnah, I-40/240 overpasses/flyovers, Jackson Ave overpass off I-40, Mississippi River bridges, etc., etc.

As for primary roads and non-elevated interstates with high traffic volumes, it will take much longer for freezing to take place. On these roads, sleet usually causes more problems than freezing rain. However, prolonged heavier freezing rain can also create ice on these thoroughfares, especially after several hours of ice. Afternoon travel will be more hazardous that morning travel.

4.  Why isn't the state DOT pre-treating the roads?

The salt brine that is used to pre-treat washes off in rain.  Since rain will occur up until the freezing rain starts, there's no time to do that.  All treatment efforts will be directed to post-freeze traction control and melting.  In other words, the elevated roadways will likely freeze BEFORE they are treated.  Expect significant delays as these areas are shut down to allow treatment and hazardous conditions otherwise!  Our guidance is "if it isn't necessary, don't get out."

5.  Any other impacts I should know about?

Certainly there are MANY activities that are subject to weather conditions this weekend.  Check with officials for that event on details.  The Marathon officials have indicated a desire to race, but have reserved the right to call it off up to 5am Saturday.  Some Christmas parades have been cancelled or rescheduled - check with your city/town.  Watch local news outlets for the latest cancellations or postponements.

Air travel could also be disrupted.  Aircraft can still fly (with a good de-ice job before take-off) but many airlines choose to preemptively cancel flights to avoid getting planes stuck in bad weather.  Check with your airline.  The airport is equipped to maintain operations throughout the event (especially given the reduced passenger flight schedules).

Many schools/colleges/educational institutions have also preemptively cancelled classes.  These include Shelby County, Memphis Catholic, Tipton County, Fayette County, DeSoto County (half day), University of Memphis, and a host of others.  Check with local news outlets or your school's website or social media feeds for the latest info.

There will be lots of other residual impacts, lasting throughout the weekend. We couldn't possibly get into them all.

6.  How does this storm rate against the Great Ice Storm of 1994?

The setup is very similar (and a classic one for an ice storm), however the total ice is not expected to come close to 1994, which saw 2" of ice in the metro and 4"+ in parts of north MS.  That doesn't mean it won't pack a punch.  The NWS says 1/4" of ice is an "Ice Storm" for a reason.  The 1994 event also took place over 36-48 hours.  (It also saw 70 degrees the day before the storm hit... hmmm)


7.  You mentioned "round 2" on Saturday night. What's that all about?

The "Forgotten Ice Storm" may be the one on Saturday night.  Another round of freezing rain, with maybe a little sleet, will move through on Saturday night into Sunday morning.  With all the attention on Friday's storm, this one will get overlooked until Saturday and will catch many off guard.  Potential exists for another 1/4"-1/2" of ice from late Saturday evening until mid-morning Sunday before changing to rain for the remainder of the day Sunday.  By itself, this would get as much attention as Friday's storm.

The real issue with this storm will be the CUMULATIVE effect of it being the second storm.  If 1/2" of ice accumulates on Friday and very little melts on Saturday, then another 1/4" falls Saturday night, then you have nearly 3/4" of ice on trees and power lines Sunday morning.  Anything weakened by the first round could be severely damaged by the second.  This is why we are recommending preparing for multiple days of impacts.  Many could lose power on Friday; many more could be added to the list Saturday night.

8.  So how should I prepare?

It's almost too late to be talking about this, but things you can do include: having 3-5 days of food and water plus medications, filling up with gas, making sure your most-used devices are fully charged (and keep them that way throughout).  Also, have candles and/or portable/space heaters (it'll be very cold all weekend and through much of next week) ready and think about neighbors or friends/family who rely on electricity for oxygen or other medical needs and have a backup plan.  Stock up on batteries and have flashlights handy, fill bath tubs with water and use a pail to flush toilets if necessary, and wrap pipes and let faucets drip if they are against exterior walls to avoid freezing.

Make it an adventure by breaking out some family games if power goes out!  Don't forget about your outdoor pets either!  Make sure they have a warm place to stay where their water won't freeze.  Remember that a full tank of gas and a car charger can keep your cell phone going as long as cell towers are working. Additional tips can be found on this Red Cross flier (PDF).  The Red Cross also provides this power outage info sheet (PDF), including what to do before, during, and after a prolonged outage.  Never run a car in a garage with the door completely closed and keep space heaters away from flammables, curtains, etc.!  Finally, be prepared to restrict travel to only necessary and vital trips if conditions get bad.

9.  How can I stay up on the latest information about local weather, preferably from a very reliable local source?

We're glad you asked! MemphisWeather.net has you covered all weekend in multiple ways!  Our main website has everything you need to stay in touch with current conditions, forecast conditions, radar with precipitation type, and much more.  Our mobile site and mobile apps for Android and iPhone also have the same information.  The mobile apps also provide our StormWatch+ push notification-based weather warning system.  For about 1/3 the cost of a low budget weather radio, we can provide instant notification of changes in weather warnings, watches, and advisories from the NWS for YOUR location, not your county.

Finally, we're all over social media and provide the most current information, including nowcasting of local conditions and imminent hazards, via our social channels. They are all linked from our websites, as well as at the bottom of this post.  Facebook and Twitter are your best sources of local weather info from MWN, specifically for the Memphis metro.  Nearly every piece of information we provide has a backup method or source in case the primary fail,s including updating the social feeds from a remote location that will not get ice (thanks to awesome interns in Starkville, MS!).

10.  Anything else I need to know?

Just this, if you haven't stocked up yet:




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Wednesday, December 4, 2013

Details on Friday's expected ice storm in the Mid-South

As most people in the Memphis metro know by now, unless they haven't had TV or radio on and haven't looked at a forecast in the past few days, winter weather is taking aim on Friday.  This is hard for many to fathom given that it's 75 degrees today, thus there are plenty of doubters.  However, if you follow us, you know this is not a test, and if you were here in 1994 you will remember that it was 70 degrees a day before the big Ice Storm of '94 hit.  This blog will provide a little more detail on what to expect and when to expect it, but we invite you to tune in to YouTube or Google+ tonight at 9pm for a live G+ Hangout (video chat) as a panel of experts weather geeks, lead by MWN, talk about the upcoming storm in greater detail.

We'll start with what the weather will do:
A Winter Storm Watch is in effect Friday, beginning at 3am for Tipton and Crittenden Counties in the metro and at 9am for Shelby and Fayette Counties in TN and DeSoto and Tunica Counties in MS.

An arctic cold front will move through early Thursday morning , dropping temps from the 60s overnight to the lower 40s by Thursday PM rush hour with showers around the area most of the day. Rain continues overnight Thursday night as temperatures fall into the mid 30s. By Friday morning, with rain continuing, temperatures will hit 32 degrees.  The timing of this will vary

  • early morning, possibly by 6am, for the northern metro (Tipton Co)
  • mid-morning (8-10am) for the I-40 corridor, including Shelby & Crittenden Co
  • late morning (10am-noon) for Fayette Co and our MS counties (DeSoto, Tunica, Tate, Marshall)
Freezing rain will continue throughout the morning and afternoon hours, mixing with or changing to light sleet and possibly some light snow by late afternoon.  All precip will come to an end by the evening hours (for round 1) as temperatures fall into the upper 20s.  Ice accumulations will likely average 1/4" to 1/2", though northern areas that transition earlier could see higher amounts.

NWS-Memphis graphic summarizing impacts and timing
By Saturday morning, conditions will be dry as far as falling precipitation, but it will be very cold with lows in the lower 20s and wind chill readings near 10 with a north wind at 10-15 mph.  Highs Saturday will only rise to near freezing under extensive cloud cover, so we don't expect a lot of melting to take place as we head into round 2... another round of freezing rain Saturday night that could drop another 1/4" to 1/2" before changing to rain on Sunday morning!


Potential impacts:
We expect the Winter Storm Watch to be upgraded to a Winter Storm Warning or Ice Storm Warning no later than tonight, while areas outside the current watch (including Tate and Marshall in the metro) should get a Winter Weather Advisory by Thursday morning.

With 1/4" to 1/2" of ice, accumulation could be enough to cause some damage to trees and power lines, resulting in power outages.  In fact, the Weather Service's experimental Ice Storm Index (which is being tested locally for the first time this winter), places the I-40 corridor in a level 3 ice storm based on accumulation and wind speed, which could result in "numerous utility interruptions, lasting up to 5 days" and "damage to some main feeder lines possible."

NWS experimental ice storm index forecast, depicting a category 3 storm for most of the metro.
In addition to power outages and downed tree limbs, secondary roads could be slippery, bridges and overpasses will likely be iced over and perhaps impassable, and multiple events could be forced to postpone or cancel this weekend.  Air travel into Memphis could also be affected by delays or cancellations Friday with aircraft having to deice prior to departure. Schools could also be affected Friday, but we know better than to venture into guessing what their operation plan will be!

You have basically just over 24 hours to prepare for the above impacts.  Be sure you consider what you'll do if power is out for multiple days, roads are slick, and ice covers unpaved surfaces and exposed objects. Also don't forget to consider elderly and sick relatives and friends, especially those who might require power for oxygen, etc., and your pets!

As mentioned above, we'll have a very detailed discussion, including comparison to previous ice storms and more preparedness information on our Google+ Hangout tonight.  You'll have an opportunity to ask questions via chat or the Twitter hashtag #wxchat. You can watch live and chat via this MWN webpage and we'll also post a direct link around 9pm tonight on our Facebook and Twitter accounts listed below.

You can also get the latest information, including current conditions, our metro forecast, and StormView Radar with precip typing, via our mobile apps for iPhone and Android. In addition, within the mobile app, be sure to upgrade and add StormWatch+ for a very affordable one-time charge. StormWatch+ allows you to receive severe and winter weather warnings via push notification for just those locations YOU select. A link to the apps can also be found below.

Stay tuned for the latest!
Erik Proseus
MWN Meteorologist

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