Sunday, January 13, 2019

A weather smorgasbord this week, with an eye towards an Arctic air intrusion

We had a few nice days this past week with mild temperatures and some sunshine that allowed the ground to dry out a bit. Of course, that was followed quickly by more rain and, today, cold weather and dreary cloud cover. Looking ahead, we'll get a mix of clouds, some sun, cold weather, warming temperatures, and rain - all in the next 5 days. By next weekend, a significant pattern change is on the horizon.

Sunday night - Monday clouds

Despite high pressure building in, as we sometimes experience in winter with low sun angles and lots of low-level moisture, clouds will stick around tonight into Monday. We stayed near 40 today with a cold wind, but decreasing dewpoints on that north wind means temperatures will drop to near or just above freezing tonight. The clouds will keep the mercury from rising much Monday with highs very near what they were today, but just a bit less wind.

Sunday afternoon visible satellite imagery shows the Mid-South locked under widespread cloud cover. The clouds will persist through Monday at least. (College of DuPage)

The cloud party should break up Monday night as high pressure moves overhead with calm conditions and lows near 30.

Tuesday - Wednesday sun

For now, we believe abundant sunshine is ahead on Tuesday with highs back into the upper 40s. The NAM model, which is typically-more-aggressive with low clouds, thinks otherwise, but I feel optimistic.

Despite some high clouds moving over on Wednesday, south wind should finally being our temperatures back above normal. Morning lows in the upper 30s will rise to the mid 50s Wednesday afternoon and conditions remain dry.

Thursday rain - Friday dry

Thursday appears to be our next wet day as a weak system moves by in fast westerly flow at the jetstream level. It will be above normal temperature-wise though with lows in the 40s and highs in the upper 50s. Rain should not be heavy on Thursday. Thursday night into Friday looks dry and mild as we sit between systems, keeping a wary eye to the west. A few showers may arrive Friday evening, but not before highs climb above 60 degrees on south wind.

Weekend pattern shift

The "wary eye" mentioned above is because we'll be seeing an Arctic airmass drop into the Plains late this week that pushes into the Mid-South on Saturday. Timing of that cold air arrival is still TBD, but for now, we project a fairly wet day Saturday with a chance of thunderstorms due to the strength of the front moving in and a fair amount of wind. Temperatures will drop precipitously behind the front, potentially during the day Saturday, but very likely by Saturday night.

The Sunday morning GFS model forecast of surface features and precipitation from this Thursday night through next Sunday shows next Saturday's storm system moving through with rain and a potential for some light snow. At this point, various models disagree on the timing of cold air and moisture departure, and thus snow chances. The nature of the system though doesn't lend itself to more than light snow, if anything. (WeatherModels)

Will all the precipitation be gone before the cold air arrives? Model solutions vary on that as well. We'll be monitoring. Needless to say, behind that front, a bitterly cold airmass arrives, sending temperatures well below freezing by Sunday morning. Even with sunshine on Sunday, we may not reach the freezing mark for highs! That will be some 20-30 degrees colder than Saturday.

The European Model ensemble system predicts about a 25% chance that Memphis will get above freezing next Sunday, based on 50 runs of the European model this morning. (WeatherBell)

Winter arrives!

The long-range outlook indicates that next Sunday is the beginning of an overall pattern shift that brings in a run of below normal temperatures, perhaps continuing into early February. It's a pattern that will make precipitation forecasting somewhat tricky with each front/low pressure system that affects the area after that. Winter is NOT over snow-lovers! Do not give up hope just yet!

The NOAA temperature outlook for the end of January and first week of February indicates more cold air is likely on the way for the eastern half of the U.S. Stay tuned!

As always, look to the web or our MWN mobile app for the latest forecast information and to our social media platforms for the most up-to-date current trends. All links are below.

Erik Proseus
MWN Meteorologist

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