Friday, November 17, 2017

A cold front that means business and an early look at Turkey Day

The weekend before Thanksgiving brings lots of activities across the area, not the least of which is a Memphis Tiger football game with conference championship implications at 11am Saturday, as well as the downtown Memphis Christmas tree lighting event and a Christmas event in Arlington later in the day. So what's this big cold front we've been heading about? Let's get into the details.

Friday Night

You have to know that gusty south wind and temperatures in the lower 70s in mid-November, like we have today, are typically followed by a dose of reality just around the corner. That is certainly the case this time, as a cold front is getting ready to barrel across the region on Saturday. Today is "prep day" with that south wind pushing higher dewpoints (aka, more moisture) into the Mid-South. The wind will pick up even further tonight as the front makes progress in our direction with southerly gusts that will exceed 30 mph and could approach 40 mph! That will keep temperatures mild overnight (in the 60s), though precipitation chances are very low.

Surface low pressure will be located in southern Kansas and heading towards the Ohio Valley tonight into Saturday. Overnight into Saturday morning, the low combines with high pressure to our east to bring gusty southerly wind to the area. (PivotalWx)


As low pressure in the Plains moves east-northeast across the Midwest/Ohio Valley on Saturday, a cold front will sweep across the Mid-South. Current ETA for Memphis is 1-2pm, but that could vary an hour either way.  Ahead of the front, the strong southerly wind will continue with temperatures rising to 70° by noon. If you're tailgating, it'll be short sleeve weather with tie-downs for your tents a MUST. In addition, a few scattered showers are possible in the morning but they should be brief as the cloud-level wind will be pushing them at nearly highway speeds (for those that don't speed...).

After lunchtime, and probably during the second half of the Tigers game, when Riley & Co. will be in the midst of raining touchdowns on SMU (Go Tigers!), the front will arrive at the speed of Tony Pollard's kickoff returns. You'll know when it hits, because it'll be marked by a sudden wind shift to the northwest, a brief period of potentially heavy rain, and possibly a rumble of thunder. The line of rain along the front looks to be narrow and fast-moving, so it may only last 10-15 minutes. Don the ponchos over the short-sleeve shirts, then be prepared to quickly add a sweatshirt layer once the rain ends! Once the quick-hitting rain ends, the wind turns cold and just as gusty (25-35 mph) and temperatures head down, tumbling quickly into the 50s.

The high-resolution NAM model from Friday morning shows scattered light showers Saturday morning (the beginning of the loop above) then a narrow line of heavy rain along the cold front by early afternoon. The latter half of the loop is Saturday afternoon into early evening and shows dry weather behind the front. (Tropical Tidbits)

The good news is that the rain threat ends once the front passes, mid to late afternoon and evening activities will be dry. Temperatures continue to fall into the upper 40s by tree lightning time downtown (5:30pm) and the blustery wind starts to let up, though will remain at 10-20 mph into the evening hours. If you have evening plans, think warm coats, not the shorts you had on in the morning!

As for a severe weather threat, the Storm Prediction Center currently has the metro on the edge of a "Marginal" (category 1 of 5) threat. There is meager instability ahead of the front and plenty of wind energy, so a brief wind gust to 60 mph is possible, though not likely, in the line that moves through along the front.

A Marginal Risk of a few severe wind gusts are predicted by the NWS for portions of the area in dark green. The thunderstorm threat, as well as severe threat, is very low (category 1 on the 5-point scale). (SPC)

The Tigers seemingly have been snake-bitten by weather events this year, but this event at least looks to be brief (outside of the sustained wind), so grab the poncho and #PackTheBowl for what promises to be a great football game! #StripeUp

The graph above shows temperature forecasts from several high-resolution models from tonight through Sunday. The black line is the model average. Note the very warm temps overnight, the large drop Sunday afternoon, and much cooler weather on Sunday, despite sunny skies. (NOAA)

Sunday and beyond

High pressure quickly builds in, making for a return to November-esque weather with highs generally in the 50s for Thanksgiving week and lows that could threaten freezing outside the city on Monday morning. A reinforcing shot of cool air arrives Tuesday night with freezing temperatures again possible Thanksgiving morning. Highs on Turkey Day will be cool - in the lower 50s most likely. Weather looks dry next week though, as any flies in the ointment that might bring precipitation stay well to our south in the Gulf.

Stay up to date with the latest conditions and forecast, as well as monitoring our Twitter and radar feeds, via the MWN mobile app. We appreciate your support of MWN in this small way, which pays big dividends for you!

Erik Proseus
MWN Meteorologist

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