Friday, September 23, 2016

Another hot weekend, then FALL arrives!

Tired of the heat? Yeah, me too.  If you can hold out another couple days, I have great news!


Despite fall officially starting on Thursday morning (you didn't try balancing an egg on end at 9:21am did you?), summer weather continues for a few more days. Thursday's high of 95° came within a degree of the record and we'll threaten the record high of 96° again today, as well as the 95° records both Saturday and Sunday. High pressure ridging aloft more typical of mid-summer is to blame. I'm over it...

Mid-afternoon temperatures on Friday are well above normal for many areas east of the Rockies under the dominance of high pressure aloft. (Wright-Weather.com)
But by Monday, we'll start to see the major pattern shift as a massive upper-level trough over the western U.S. this weekend, upstream from our large ridge of high pressure, begins shifting east. It'll flatten out some as the main low pressure area goes by well to our north. However, it will be enough to push a cold front slowly south through the region Monday and Tuesday, resulting in a chance of showers and a "seepage" of more autumn-like air into the Mid-South.

The European model shows the upper level pattern (500 mb/18,000 feet) on Saturday morning dominated by a large trough of low pressure in the west and huge ridge of strong high pressure in the east, centered over the Mid-South. Weather systems moving across the U.S. roughly follow the black line. (PivotalWeather.com)

According to the European model (and GFS, not shown), as the low in the image above lifts northeast into southeast Canada by Tuesday morning, the eastern U.S. ridge flattens, allowing cooler air to drop south. Meanwhile, a ridge builds back to the west. As it shifts east later next week, temperatures will warm back up, but likely not to the levels we see this weekend. (PivotalWeather.com)
The rain chances with this front, despite there being a fairly large temperature gradient across it, will be fairly low thanks to most of the moisture remaining to our west in the southern plains and the dynamics associated with low pressure heading well to our north. Severe weather is not on the docket. The best rain chances will be Monday into Monday evening (and even then only about 30%). We could use some rain, so the little we might get will likely just set the stage for continued dryness next week as cooler high pressure builds in.

The Short-Range Ensemble Forecast (SREF) model data shows probabilities, including this map of probabilities of 0.10" of rain through Monday afternoon. The best rain chances over the next few days occur to our west. The SREF indicates only about a 30% chance we'll see 0.10" of rain with Monday's front. (WeatherBell)
Behind the front, we'll see temperatures more akin to "normal" for late September - cool mornings in the 50s (especially outside the city) and highs in the upper 70s to near 80. Mid-range model data has some disagreement in the strength of the cool air though. If the American GFS model wins out, outlying areas COULD see some lows in the upper 40s by mid-week. For now, that seem a bit of a stretch.

The GFS Ensemble Forecast System (GEFS) consists of multiple iterations of the American GFS model. Above, the average high and low temperatures from the GEFS members show a very welcome shift from summerlike temperatures to fall early next week. Note that its European counterpart (not shown) is similar but not as cool especially for morning lows, next week. (WeatherBell)
In the long-term, it appears this current streak of 90s may be our last for this year, but above normal temperatures are expected to return by early October.  The good news is that "above normal" for that time of year puts us in the 80s and humidity values are expected to remain tolerable. Here's to the arrival of fall next week!



From NOAA's Climate Prediction Center, there is a high probability that temperatures return to "above average" for the first week in October for most of the country east of the Rockies. (NOAA/CPC)

Erik Proseus
MWN Meteorologist

----
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

Friday, September 16, 2016

Rain for weekend activities? And what about this heat?

I spent a very worthwhile several days in Norfolk, VA this week at the National Weather Association Annual Meeting. The NWA is one of two professional organizations for meteorologists, geared primarily towards operational forecasters. There were lots of great presentations and networking opportunities, but I'm glad to be back! Here's one of my favorite pics - Jim Cantore really is a great guy!


As we get deep into mid-September, it's about time for the heat to depart! This week has been another cooker with highs in the mid to upper 90s. Fortunately, dewpoints have been a bit lower than when we had these same temperatures in the midst of summer, so heat indices have remained below 100 for the most part. As we head into a busy weekend for outdoor events, such as the Cooper Young Festival, a Memphis Tigers football game, and of course Friday night high school football, there are a couple of changes to the past week's pattern - a bit less heat and a bit more rain!

Starting tonight, things are looking good, but warm, for football. Temperatures will settle into the 80s by dusk and rain chances are minimal. Wear your favorite school's t-shirt and leave the umbrellas at home.


By Saturday morning, the ridge of high pressure that has dominated our pattern this week will move east as a large upper-level trough moves closer. That will push a front into the area and rain chances go up. There could even be showers around by dawn tomorrow, but the best chances look to be from mid-morning through early afternoon. Rain chances right now stand at about 50% but a complete washout is not expected.

If you have plans to go to Midtown for either of the two big draws tomorrow, bring your poncho and have a good time, but expect some rain at some point and keep your eyes and ears open for lightning and thunder. Your MWN app will come in handy, even though the NWS Doppler is down. Our radar will continue to show you what's headed your way. Rain amounts will generally be in the 1/2" range with some areas seeing a bit more or less.

The American GFS model showing expected rainfall totals through 7pm Saturday. Heaviest rain, and highest rain chances will be to our north, but scattered showers and a few thunderstorms are also expected locally, mainly in the middle part of the day. (PivotalWeather)
The Storm Prediction Center severe weather outlook for Saturday shows a risk of "general" (non-severe) thunderstorms in the metro. Severe weather is more likely well to our west. (NOAA/NWS/SPC)
As mentioned, thunderstorms are also possible, but severe weather is not anticipated. There's just not going to be enough upper level wind energy or low level instability to generate strong wind or hail. If lightning is nearby, take your lightning safety precautions. Your car is the best place to be if a sturdy structure is not accessible, but indoors is best. They'll put you on the concourses at the Liberty Bowl if lightning threatens, but trust me, that's only marginally safer than the exposed bowl. If you can find a way to get walls around and over you, that's better.



Rain chances go down in the evening as the upper level wave responsible for the daytime activity moves east. Levitt Shell and other evening activities have a better chance of remaining dry than those earlier in the day, but a shower is still possible well into the evening.

Sunday is questionable. Some models dry us out, others hang some atmospheric energy back and keep rain chances in the forecast. With the core of the upper level trough moving overhead, the prudent forecast maintains at least a chance of showers or a thunderstorm, which I have done. Probability of precipitation is 30-40% Sunday, subject to change. If you're picking the drier day this weekend for outdoor stuff, Sunday is your best bet.

The American GFS model at 500mb (18,000') shows the trough moving through Sunday evening that ends rain chances as high pressure builds quickly in behind it, escorting heat back into the Mid-South next week. (PivotalWeather)

Heading into next week, unfortunately a summer-like ridge of high pressure builds over the central U.S. once again and we heat back up. The MWN Forecast is carrying 90's throughout the week with mid 90s quite possible in the middle of the week, and virtually no rain chances.



The mid-level weather pattern for the middle of next week, as shown by the American GFS model, is dominated by anomalously high pressure over much of the CONUS and centered over the Southern Plains. This will lead to hot conditions. (WeatherBell)
The good news is that in the long-term (a week to 10 days out), I'm seeing a fairly strong pattern shift that should bring more autumn-like weather to the region for the end of September. It can't come soon enough!



Erik Proseus
MWN Meteorologist

----
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

August 2016 Climate Data for Memphis, TN

August Recap

Summer continued full bore in August as the hot weather of June and July continued into the month. In fact, August placed in the top 10 hottest on record in Memphis (#10), meaning that all three summer months were ranked in their individual top 10 warmest. At the end of August, a new record was established for consecutive days above 70°, standing at 82 days. The hottest day of the month was 99° on the 5th.


The summer will best be defined by its persistent heat and warm nights, not extreme highs, as the mercury only touched the 100° mark on one occasion. A two-month-long streak of average temperatures above 80° ended in the middle of the month, as well as a 72-day streak of highs at or above 88°. Both of these streaks rank in the top 3 longest on record. The average temperature of 84.3° for June-August was 2.9° above the climate average and ranks as the 4th hottest summer in Memphis' recorded history.


In terms of precipitation, the month started dry, but thunderstorms were abundant during the mid-month period, ending with above average rainfall for the metro by over 2.5". Four days recorded more than 0.75". For the summer season, Memphis ended with 14.72" of rainfall which is 3.62" above the long-term climate average. Only two severe weather warnings were issued for the month in the metro, one over Memphis and the other for eastern DeSoto and northwest Marshall Counties. No severe weather reports were received in the Memphis metropolitan area.

Memphis International Airport, Memphis, TN

Temperature
Average temperature: 84.6 degrees (2.6 degrees above average)
Average high temperature: 92.5 degrees (1.2 degrees above average)
Average low temperature: 76.7 degrees (4.0 degrees above average)
Warmest temperature: 99 degrees (5th)
Coolest temperature: 70 degrees (22nd)
Records set or tied: Daily record high minimums (warmest low temperatures) were tied on the 2nd (81°), 10th (81°), and 30th (79°).
Comments: 22 days recorded highs at or above 90 degrees in August, which is 2.8 more than average. This month tied for the 6th warmest August on record in Memphis. For the year, the average temperature is 67.0 degrees, which is 2.0 degrees above normal and ties for fourth warmest January-August period on record.

Precipitation
Monthly total: 5.53" (2.65" above average)
Days with measurable precipitation: 10 (3.2 days above normal)
Wettest 24-hour period: 1.82" (20th-21st)
Records set or tied: None
Comments: Three days recorded one inch of rain or more. Through the first seven months of 2016, Memphis International Airport has recorded 49.81" of precipitation, or 14.43" above average (141%). That also ranks as 7th wettest on record for the January-August period.

Miscellaneous
Peak wind: South/45 mph (25th)
Average wind: 5.7 mph
Average relative humidity: 69%
Average sky cover: 50%

Click here for a daily statistical recap for Memphis International Airport.

Cirrus Weather Solutions / MemphisWeather.net, Bartlett, TN

Temperature
Average temperature: 81.1 degrees
Average high temperature: 91.3 degrees
Average low temperature: 73.3 degrees
Warmest temperature: 97.9 degrees (4th)
Coolest temperature: 64.9 degrees (22nd)
Comments: None.

Precipitation
Monthly total: 3.30" (automated rain gauge), 3.48" (manual CoCoRaHS rain gauge)
Days with measurable precipitation: 11
Wettest date: 1.03" (15th) (via automated gauge)
Comments: None

Miscellaneous
Peak wind: 15 mph (14th)
Average relative humidity: 84%
Average barometric pressure: 30.00 in. Hg

Click here for a daily statistical recap for Bartlett, TN.

MWN Forecast Accuracy

MWN average temperature error: 1.95 degrees
MWN forecast temperatures within 2 degrees of actual: 67%
MWN average dewpoint error: 1.42 degrees
MWN forecast dewpoints within 2 degrees of actual: 81%

MWN's forecasts extend out five periods (2.5 days, or roughly 60 hours). Historical accuracy statistics can be found here.

----
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

Friday, September 9, 2016

Another cold front gets us one more step closer to autumn

As we get deeper into September, the resumption of heat and humidity behind cold fronts that now arrive about once a week is slightly more bearable (though low to mid 90s is still too hot for this time of year). A sign of the times as we near fall! As we head into the weekend, another cold front pushes through with a rebound in temperatures behind it, but not quite to the extent of this week's 90s.

This weekend brings that next front, more specifically during the day Saturday. It will be accompanied by scattered showers and thunderstorms, with about a 40% chance of rain most anytime during the day. The additional cloud cover and scattered precip will keep temperatures in the 80s and wind will shift to the north by late afternoon.

The surface map for Saturday morning shows our cold front approaching. I(t will move through in the afternoon accompanied by scattered showers and thunderstorms. (NOAA/NWS)

The effects of the front will be most pleasantly felt on Sunday and Monday with highs remaining in the mid 80s and cooler lows in the 60s, as well as low humidity and a sunny sky. If you have outdoor things to do, Sunday is going to be gorgeous!

Behind the cold front, drier air, as seen by dewpoints in the 50s, will make for a very pleasant Sunday. Plan to get out and enjoy a taste of fall as highs remain in the mid 80s! (pivotalweather.com)

Heading into next week, we'll start to see a slight rebound in those temperatures back to the 90° range or so though humidity won't be oppressive. A couple showers are possible in the afternoon hours, especially mid-late week. Yet another front looks to slowly drop in from the north late next week, bringing a slightly-cooler airmass than the preceding one. As mentioned above, it seems that each front starts to reinforce that fall is coming soon!

I'll be in Norfolk, VA for the National Weather Association Annual Meeting this weekend and the first half of next week. It's a great conference with lots of learning and socializing with other weather geeks, as well as gaining continuing education towards the Digital Seal of Approval displayed below. Thanks as always to #TeamMWN for keeping the home fires burning! Have a great weekend!

Erik Proseus
MWN Meteorologist

----
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