Sunday, June 25, 2017

The Summer Swing Begins in Memphis This Week

Are you ready for the summer? Are you ready for the sunshine? We've got warmth and sunshine for much of our week ahead, but some storms could rain on our parade heading into later this week. Let's dig into the details.


A Sunny Start
Sunday has brought abundant sunshine throughout the afternoon for the Memphis area and temperatures running mostly in the mid-80s. Lower humidity helps too, and that pattern is likely to continue into the beginning of the work week. Temps will slide into the mid-60s on Sunday night with partly cloudy skies, before jumping back up to the mid-80s on Monday.

The next chance of showers and storms comes on Monday night as a "reinforcing" cool front pushes through, though any precipitation should be isolated in nature and mostly remain to our north. There will be a likely increase in clouds on Monday ahead of any rain, but overall should be a good day.

Tuesday will see any early clouds decreasing with continued low humidity and warm temperatures. Wednesday continues the pattern of warmth, albeit with slowly rising humidity. It could become a bit more sticky, but temperatures remain in the mid to upper 80s for highs the middle of the week. The sun will remain a prominent feature in the forecast those days, while overnight will see mostly clear skies and lows in the upper 60s to near 70. Be sure to keep yourself and your pets cool in the heat of the summer coming up.

Here are some smart tips on how to keep your pets safe and cool this summer.

Summer Storms Are Coming

As the latter part of the week approaches, there is an increasing chance of pop-up showers and thunderstorms around the metro area. With the heating of the day where temperatures could approach 90 degrees, along with increased humidity, it would not be surprising to see some storms fire up late in the afternoon and into the early evening hours.

Temperatures continue to remain warm through the rest of the week with highs in the upper 80s to near 90. Lows will be on the rise too, with most nights dropping into the lower 70s.

Heading into the weekend, we will be watching an approaching cold front from the west that could bring more widespread rain and thunderstorms just in time for the weekend. Fortunately, this messy weather should clear just ahead of the July 4th holiday coming up.



Be sure to follow along with us on social media for all the latest weather for the Mid-South. Follow @memphisweather1 on Twitter or like us on Facebook. You can also download the MWN app from the Apple or Google Play stores, featuring pinpoint severe weather alerts from StormWatch+.

And one last request - the Commercial Appeal's #MemphisMost contest ends Monday morning at 9am, and we've been nominated for "Most Accurate Forecast" for the first time ever! Please consider casting a vote at www.MemphisMost.com tonight or early Monday. You can even vote once an hour! Thanks much and have a great week!

Alex Herbst, Meteorologist
MWN Social Media Intern

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Visit MemphisWeather.net on the web or m.memphisweather.net on your mobile phone.
Download our iPhone or Android apps, featuring StormWatch+ severe weather alerts!
MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder

Saturday, June 24, 2017

2017 Solar Eclipse: A Viewing Guide for Memphis and the Mid-South

On August 21, the first total solar eclipse to make an appearance over the continental United States since 1979 will pass within 150 miles of Memphis. The last time a total solar eclipse spanned the contiguous U.S. (as this one does) was 1918, nearly a century ago, and the first total solar eclipse visible anywhere in the CONUS in 38 years. Despite the area of totality missing Memphis by a short drive, most of North America, including the Memphis metro, will experience a partial eclipse. In the case of Memphis, the sun's obscuration will be 93%, so nearly total!

What is a solar eclipse?

From NASA's total eclipse page, eclipses occur when the sun, moon, and Earth periodically align. Solar eclipses happen when the moon moves between Earth and the sun. When the moon eclipses the sun, it produces two types of shadows on Earth. The umbral shadow is the relatively small area on Earth where an observer would see a total eclipse. The penumbral shadow is the much larger area where an observer will see a partial eclipse. Here, the sun is not completely covered by the moon.


During a total solar eclipse, there is as noticeable drop in light level (like twilight) and, subsequently, air temperature. The brightest stars and the planets become visible. Animals act like it is nighttime with birds and squirrels nesting and crickets chirping. In other words, there is nothing quite like it during the middle of the day!

Solar eclipse of July 22, 2009 taken by Lutfar Rahman Nirjhar from Bangladesh.

Mid-South Path

The Memphis metro will not be in the path of totality of this year's solar eclipse, but will be well within the area of a partial eclipse. In fact, for the Memphis area specifically, the sun achieves 93% obscuration, or very near totality. The nearest areas which will have a total eclipse are about 150 miles northeast of Memphis as shown in the map below.

The path of the total eclipse is shown above in the map generated by NASA. Times of maximum eclipse at various points are provided as well as the duration of the total eclipse (which is higher the closer to the center of the shadow you are).

As for the timing of the partial eclipse event here in the Memphis area, here are the pertinent details:


If you are considering a trip to see the total eclipse, the closest large cities within the path of totality are Nashville and Paducah, although anywhere along the path shown in the map above will do!

Eclipse details for Nashville:

Start of partial eclipse: 11:58am CDT
Start of total eclipse: 1:27:26pm CDT
Point of maximum eclipse: 1:28:25pm CDT
End of total eclipse: 1:29:23pm CDT
End of partial eclipse: 2:54pm CDT

Eclipse details for Paducah:

Start of partial eclipse: 11:54am CDT
Start of total eclipse: 1:22:17pm CDT
Point of maximum eclipse: 1:23:28pm CDT
End of total eclipse: 1:24:39pm CDT
End of partial eclipse: 2:49pm CDT

You can look up these same details for any location in the United States from this site.

Will weather cooperate?

Of course the other major consideration on an eclipse day is cloud cover. If it is overcast, it won't matter whether an eclipse is occurring because you won't be able to see it! NOAA's National Centers for Environmental Information (NCEI, formerly NCDC) has done research on local climate data (cloud cover specifically) to determine the "viewability" of many locations within the eclipse area. Shown below is a map of eclipse viewability in the region of interest for Memphians. Each dot is shaded according to how likely that location is to produce good viewing conditions based on historical record (of course anything could happen on August 21, 2017!).

Here in Memphis, the climatological record says there is a 51% chance that the eclipse is viewable, with cloud cover being scattered or less 61.6% of the time historically. In Nashville, the "viewable ratio" is just 44%. The closest locations with the best potential for good viewing conditions within the path of totality are Paducah and Cape Girardeau, MO (both 77% "viewable").

The area of total eclipse is shown in dark red and at least 90% obscuration is in orange. The surrounding lighter orange color will have more than 75% obscuration. The shaded dots represent the historical "viewability" for indicated areas with a whiter dotter indicating a better chance of less cloud cover, or greater "viewability." For an interactive version of this map, click here.  (NOAA/NCEI)


Viewing tips

Looking directly at the sun is unsafe except during the totality phase of an eclipse, when the moon entirely blocks the sun’s bright face, which will happen only within the narrow path of totality as described above. That will NOT occur in the Memphis area, as we'll experience only a partial eclipse (even though only 7% of the solar disk will be visible locally, it's enough to burn your retinas if you look directly at it).

The only safe way to directly view a partial eclipse sun is through special solar filters, such as “eclipse glasses” or hand-held solar viewers. Homemade filters or ordinary sunglasses, even very dark ones, are not safe for looking at the sun. Four manufacturers have certified that their eclipse glasses and handheld solar viewers meet the international standard for such products. One of those manufactures eclipse and 3-D glasses for worldwide use right here in the Memphis area - American Paper Optics of Bartlett!


All glasses or solar filters should be inspected before use. If scratched or damaged, discard them. To view the eclipse, stand still and cover your eyes with your eclipse glasses or solar viewer before looking up at the bright sun. After glancing at the sun, turn away and remove your filter — do not remove it while looking at the sun.


If you decide to travel to a location that experiences totality, you can safely remove your solar filter or glasses only when the moon completely covers the sun’s bright face and it suddenly gets quite dark. As soon as the bright sun begins to reappear, replace your solar viewer to glance at the remaining partial phases (see above tips).

An alternative method for safe viewing of the partially eclipsed sun is pinhole projection. You may remember doing this for previous partial eclipses in the past. Here are instructions to make a very simple projector out of cardboard.

Viewing an eclipse can be done with solar glasses or with a "pinhole camera," which is diagrammed above.

For more information on the eclipse, we recommend the following sites, which are full of great information:
Now we need to all cross our fingers for a sunny day on August 21!

Erik Proseus
MWN Meteorologist

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Follow MWN on Facebook, Twitter, and Google+
Visit MemphisWeather.net on the web or m.memphisweather.net on your mobile phone.
Download our iPhone or Android apps, featuring StormWatch+ severe weather alerts!
MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder

Wednesday, June 21, 2017

Remnants of Cindy to pass over the Mid-South Friday

We've been keeping a close eye on (potential, then actual) Tropical Storm Cindy in the Gulf of Mexico the past few days. For the first time in several years, the remnants of a former tropical system are set to pass directly over the Mid-South. First, here is the latest forecast track of Cindy (click any image on this page for a larger version):

Latest forecast track of Cindy from the National Hurricane Center.


Forecast Path

As you can see from the graphic above, as of early Wednesday evening, Cindy is expected to make landfall early Thursday morning near Beaumont, TX, or along the TX/LA border. It will be a moderate tropical storm with maximum sustained wind near 45-50 mph when it makes landfall. From there, it heads north up the TX/LA border then begins a right turn Thursday night, heading into southern AR, That right turn continues, moving what will likely be Tropical Depression Cindy, over the Mid-South, if not Memphis proper, on Friday around mid-day. There are some model discrepancies on the exact track of the center of the low and the timing, but it will be during the day Friday.

Effects on the Mid-South

The effects here in the Mid-South will primarily be those that were problems to our south today - some gusty wind, not-insignificant rainfall which could lead to some flash flooding, and as with any landfalling/remnant tropical system, a few strong storms that could produce brief tornadoes. We'll take them one at a time.

Wind

Wind has not been a major factor even while Cindy was a tropical storm today. Strongest wind of up to 40-50 mph was primarily right near the center and in convective bands well removed east and north of the storm. Cindy will weaken after landfall, but we'll see breezy conditions (10-20 mph, some higher gusts) through Thursday night. On Friday, as the low approaches and depending on its exact track, some areas could see sustained wind of 20-30 mph with a few gusts to 40+ mph, mainly in convective (thunderstorm) bands and near the path of the low. By Friday evening, any strong wind will subside back to the baseline of 10-20 mph. Widespread power outages are not anticipated, but with a slightly weakened grid due to remaining tree limbs on lines, etc. from recent storms, sporadic or scattered outages are possible, mainly Friday.

Heavy rain and flooding

The primary threat from Cindy is, and will continue to be, periods of heavy rain and the potential for flash flooding. Timing of any "bands" or "slugs" of moisture is very difficult more than several hours out, so trying to pinpoint exact times of when they will occur is borderline futile. Suffice it to say, rain chances will be high from late tonight until the system passes late Friday, however it is not expected to rain hard the entire 2-day period.

For now, it appears showers will begin to overspread the area tonight with the first main band moving through early Thursday morning. After this round, there could be a lull during the mid-day hours tomorrow, although given the unstable and very moist atmosphere that is in place, scattered showers and thunderstorms are probably a decent bet. Another round could affect the metro late tomorrow into the early overnight Thursday night, though that may set up just to our north. (Again, this is not set in stone.) Then, indications are that we'll see one more period of rain, probably the heaviest, associated with the approach, passage, and departure of the low itself during the day Friday, quite possibly lasting into Friday evening. Again, this is HIGHLY subject to change. (If you have tickets to Live at the Garden Friday night or plan to attend a Levitt Shell concert, watch for information from those entities on their plans and stay tuned to the forecast. Even if it isn't raining during the concert times, conditions may be too wet leading up to the events to get them properly setup.)

Overall, rainfall totals could vary quite a bit from one place to another but are expected to generally fall in the 2-3" range between tonight and Saturday morning with some areas seeing up to 5". Flash flooding and urban ponding/flooding are possible. Flash Flood Watches are not currently in effect but I put odds at better than even that they will be before Friday. Our area is under a Moderate Risk of flash flooding for the Thursday night/Friday period, as shown below.

Rainfall projections from the NWS through Saturday morning show a band of 2-3" of rain expected across the metro. A few locations could see more, and possibly less, as these numbers are approximates. Memphis is just northeast of the 2-3" annotation in the center of the image. (NWS/WPC)

The Weather Prediction Center forecasts a Moderate Risk (10-15% chance) of flash flooding on Friday for the metro. (NOAA/WPC)

Brief tornadoes

Thunderstorms associated with remnant tropical systems build in highly-sheared environments where wind at various levels of the atmosphere is blowing briskly, and in varying directions. This can lead to the threat of spin-up tornadoes in some of these storms, even those that may not contain lightning or be severe by any other definition. (Storms from tropical systems tend to have much less lightning than a "normal" summertime thunderstorm and are also not as tall, but they can still pack a punch.) The greatest threat for any tornadoes will be to the right of the track of the storm. On Thursday, that threat will mainly be to the south of the metro in LA, southeast AR, and western MS where there is a Slight Risk of severe storms. The Memphis area is in a Marginal Risk on Thursday, meaning a few storms could contain brief damaging wind gusts or a spin-up tornado. (Hail is generally not a threat with tropical systems as their "core" is warm, not cold like classic low pressure systems.)

The Storm Prediction Center severe weather outlook for Thursday, showing the Slight Risk (where a tornado is most likely) south of the metro. (NOAA/SPC)
On Friday as the low passes near the metro moving northeast, the most favorable position for brief tornadoes will be in the southeast quadrant of the storm. If the low passes to our north, Memphis could be in that quadrant. If it passes just to the south or overhead, the favored area will be to our south. Currently, the Storm Prediction Center, based on the Hurricane Center track, places the Slight Risk south of Memphis with the metro in a Marginal Risk once again. That could change and will bear monitoring. Overall, the probability of tornadoes also will go down a bit from Thursday to Friday as the system weakens in general. As a last comment, the tornadoes associated with weak remnant systems in general are not the monsters we see in the Plains or Dixie Alley associated with supercells. They are more akin to the brief spin-up's that are possible with a squall line moving through, but we still need to prepare for the possibility that they could occur, and probably with little notice.

The Storm Prediction Center severe weather outlook for Thursday, showing the Slight Risk (where a tornado is most likely) southeast of the metro. (NOAA/SPC)

After the storm

By Friday night, it appears the worst will be over with perhaps a lingering shower that lasts until Saturday morning. Most of Saturday looks like it could be dry (though precipitation may hold back a little longer than current thinking) and Sunday introduces another conundrum, as computer models have fought like pre-teen siblings over whether an upper level system brings additional rain chances. Right now those chances appear fairly low. Stay tuned.



In the meantime, be sure to follow us on social media for the absolute latest on this dynamic weather situation; download the MWN app for radar, currents, the MWN Forecast, and our social feeds as well as StormWatch+ optional severe weather alerts; and check out the MWN Tropical page (optimized for desktop browsing) with more information on the current status and future of Cindy! All social and app links are listed below.

Erik Proseus
MWN Meteorologist

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Follow MWN on Facebook, Twitter, and Google+
Visit MemphisWeather.net on the web or m.memphisweather.net on your mobile phone.
Download our iPhone or Android apps, featuring StormWatch+ severe weather alerts!
MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder

Saturday, June 17, 2017

Atlantic/Caribbean tropics getting started early

Atlantic hurricane season just started on June 1, but already things look to be "heating up" in the warm waters of the Caribbean and tropical Atlantic - about a month to six weeks earlier than average.


AL93 - Yucatan/Gulf of Mexico

Near the Yucatan Peninsula of Mexico in the southern Gulf of Mexico, home to resorts like Cancun and Cozumel, a large area of low pressure will move northwest across the peninsula with heavy rain and sub-tropical wind speeds this weekend before emerging into the southern Gulf early next week.  There is still a large disparity between various computer model solutions on where this system heads once it reaches the Gulf, ranging from the Rio Grande Valley of deep south Texas/northeastern Mexico to the central to northeastern Gulf coast of the United States (think of some of our favorite beaches along the AL/FL coastline or perhaps as far west as New Orleans).

Model tracks for AL93, which will cross the Yucatan this weekend then emerge into the Gulf early next week (WxBell)
In any scenario, it would be late next week before that occurs and none of the models turns "beast mode" on for AL93 (area of investigation #93), but it'll still bear watching! ANd it's also still much too soon to know if it will have any effect on local weather in the Mid-South. If a tropical storm forms from this system, it would likely be called Bret (see 2017 storm names), owing to the fact that premature Arlene formed in the vast reaches of the central Atlantic a couple of months prior to the official start of the season. Sea surface temperatures in the Gulf of Mexico are fairly close to average (within about 1° F, with actual water temperatures near 83° F), though they are warmer than average off the Texas coast.

This map from earth.nullschool.net shows sea surface temperature anomalies in shades of red (warmer than average) and blue (cooler than average), as well as ocean currents. The Loop Current is well-established in the southeastern Gulf and the well-known Gulf Stream can also be seen flowing from the Loop Current up the east coast. The position of AL93 is shown and has near average water temperatures ahead of it, unless it heads towards the Lower TX coast.  

AL92 - Windward Islands and beyond?

If the Caribbean system isn't called Bret if/when it develops full tropical storm status, it'll only be because "AL92" in the south-central Atlantic beats it to the punch (see first graphic above)! Moving abeam the northern shores of South America in the next few days, this tropical disturbance seems to have less a chance of development in the long-run, but could be the earliest tropical developments in this part of the world on historical record! Check out the graphic below, which shows no previous development recorded in the central Atlantic during the middle part of June!
The early months of the Atlantic season are typically reserved for development in the Gulf of Mexico and Caribbean, while the long-haul trackers across the Atlantic that are born from storm systems in western Africa that take a drink in the eastern Atlantic don't start gearing up until well into the tropical season. Here are the potential tracks for AL92, which are fairly tightly clustered towards the Windward Islands in 3-4 days:

Model tracks for AL92 as it heads towards the Windward Islands in a few days (WxBell)


New for 2017

There are a couple of interesting items of note that are new for the 2017 hurricane season. First, the National Hurricane Center will have the option this year to issue advisories, watches, and warnings for disturbances that are not yet a tropical cyclone, but which pose the threat of bringing tropical storm or hurricane conditions to land areas within 48 hours.

Previously, a system must have attained tropical depression status for watches and warnings to be issued or NHC advisories to be initiated. Now, a "Potential Tropical Cyclone" can trigger advisories or watches/warnings for land prior to the storm actually officially "forming," thereby allowing more preparation time for those who might be affected in its path (but only if within 48 hours of potential impact to land).

In addition, this will be the first year that Storm Surge Watches and Warnings will be officially issued for tropical cyclones that pose a threat to U.S. soil. This additional warning type will help coastal communities to know about, and respond to, significant water rises above normal tidal levels, another step in alerting impacted communities to the various threats of hurricanes, separate from just the wind speeds expected. To learn more about these, and other new products and services that will be available from the Hurricane Center this year, check out this link.

A potential storm surge flooding map for a sample hurricane making landfall along the upper Texas coast. This is just an example of the types of maps that will be available for any U.S. land-falling tropical system this year, developed by the Storm Surge unit of the National Hurricane Center. (NOAA/NHC)
For additional resources during the 2017 hurricane season, be sure to check out MWN's Tropical Page, which we do our best to keep up-to-date throughout the season! Also, StormWatch+ is being updated to include push alerts for Storm Surge Watches and Warnings for coastal areas (remember StormWatch+ works nationwide!), so you can rest assured that if you visit your favorite beach this year, you will receive all of the pertinent alerts from the Hurricane Center and local National Weather Service office while you are there (as long as you program the alerts for your vacation destination)!

Erik Proseus
MWN Meteorologist

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Follow MWN on Facebook, Twitter, and Google+
Visit MemphisWeather.net on the web or m.memphisweather.net on your mobile phone.
Download our iPhone or Android apps, featuring StormWatch+ severe weather alerts!
MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder