A warm Turkey Day becomes a wet holiday weekend

Well, at least we can say it was a nice holiday! In fact, the high temperature in Memphis on Thanksgiving was 75°. That is not a record for the date, but I did go back 20 years into the archives and it was the warmest Thanksgiving over the past two decades.  In reviewing those years I found lots of highs in the 40s and 60s. I also found that rain has fallen on only 2 Thanksgivings in the past 20 years (2000 and 2003).

Today's Turkey Day high of 75° was the warmest Thanksgiving in Memphis in the past 20 years. Second warmest: 74° in 2010. #memwx

— MemphisWeather.net (@memphisweather1) November 27, 2015

Despite a few sprinkles, Black Friday has also turned out pretty decent too, warm and cloudy but mainly dry so far. Temperatures have been in the mid 60s most of the day. If we don't drop below this morning's low of 63°, we'll tie the daily record for warmest low temperature. We can be thankful we're not dealing with the ice storm that some in the Plains are experiencing! That speaks to the strength of the cold front to our west, if not to its (lack of) forward motion.

Heading into the rest of the weekend, a persistent upper level pattern has caused the surface front to nearly stall out as it attempts to move east through the Mid-South. This upper pattern features a fairly strong ridge of high pressure over the lower Mississippi Valley and Gulf of Mexico and a deep upper level low over the western states. In between, a broad southwesterly flow extends from the Desert Southwest to the Great Lakes, or parallel to the surface front. When this occurs, there is very little to "push" the front through and our surface pattern also stagnates.

Jet stream level (39,000') setup as of Friday evening, showing a strong southwest to northeast flow across the U.S. with a ridge of high pressure over the Gulf of Mexico and a deep and large low pressure trough over the western U.S. A surface front lined up with the jet stream aloft typically doesn't move very fast.

Eventually, high pressure over the Plains will push the front through the Memphis area, likely around noon tomorrow. Though rain is expected off and on tonight into early tomorrow (with the heaviest to our northwest), the steadier rain will move into the metro behind the front later Saturday as moisture-laden air also resides behind the front, which stalls again over north MS. Upper level disturbances moving parallel to the front will keep rain chances high right through Sunday and into Monday. This is when low pressure forms along the front and helps to finally push it east as the upper level flow flattens out, becoming zonal (meaning the air moves nearly west to east). It could be early Tuesday before we finally shake the rain chances entirely however.

By Monday evening, the southern U.S. is dominated by a strong west-to-east jet stream (what we refer to as "zonal flow") which helps to keep frontal system more progressive at the surface. Also visible is the weakened trough that was in the western U.S. moving over the jet stream across the northern Plains.

In the meantime, rainfall totals across the metro will likely end up in the 3"+ range by Monday afternoon, most of that falling between Saturday evening and Monday morning, though light amounts are to be expected tonight and Saturday, as well as during the day Monday. Flash Flood Watches are posted just northwest of the metro in Arkansas where rain totals (which include that which has already fallen) could be upwards of 6".

NWS rainfall forecast from 6pm Friday through 6pm Monday. Though the rain has held off so far, a lot is on the way, particularly from Saturday PM through Monday AM. Graphic courtesy NWS.

So keep your galoshes, ponchos, umbrellas, and rain boots handy for the next few days! For those attending Senior Day at the Liberty Bowl Saturday morning as the Memphis Tigers football team plays their final regular season game of the year against SMU, periods of light rain are possible from early day tailgating right through the game, but we're not expecting major washouts. Temperatures will be mild in the morning (lower 60s) before starting to fall into the 50s by early afternoon as the front moves through around noon, so overall not bad temperature-wise.

Surface map valid 6pm Saturday evening showing the cold front just southeast of Memphis and widespread rainfall expected along and behind it as low pressure systems ride along the front from southwest to northeast. Graphic courtesy NWS.

Much of next week features cooler weather and mainly dry, though high clouds could be abundant. Lows will drop into the 30s with highs in the lower 50s at best by mid-week. Click here for the complete "human-powered" forecast from MWN and be sure to follow us throughout the weekend on social media as we bring you the latest information!

Also, for a few more hours (ending tonight at midnight), our mobile app for iPhone/iPad is FREE for Black Friday! Click the link below to grab it before it goes back up to $0.99! (Android users will still have to pay $0.99 since Google doesn't give us the flexibility pricing that Apple does. Sorry!) We also encourage you to upgrade within the apps to add StormWatch+, or precision severe weather alert technology. You'll find it to be a very advanced version of a NOAA Weather Radio that is mobile, works nationwide, and is about 1/4 the cost of a standard weather radio. Check it out and thanks for your support in helping to make the rest of what we offer free!

Erik Proseus
MWN Meteorologist

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