Tuesday, January 22, 2019

Update on Wednesday's winter weather chances

After a semi-detailed blog yesterday that raised some hopes, it appears that Mother Nature may have pulled another fast one on us. In all actuality, a few degrees really DOES make a difference.


The main change to the forecast is that the arrival of the cold front ushering in the colder air looks to be delayed a couple of hours - instead of about 3am, it'll be closer to 6-7am Wednesday. That, along with a slight modification to the airmass coming in behind it, means that instead of temperatures dropping into the mid 30s during the morning, it will likely be into the afternoon when they get that low. Precipitation ends by late afternoon. Thus the "sufficiently cold" air that would result in a changeover to a wintry mix is pushed back to closer to when the precipitation departs. It's the age-old issue here in the South: rain moves out before cold air arrives...

So what does all that mean?  Simply put, Wednesday will likely feature a cold rain with a small chance in the mid-afternoon hours of a bit of sleet or snow mixing in with the rain. With temperatures still above freezing during the daylight hours (though cold), no significant impacts are expected, including to roads. The heaviest rain is likely just behind the front, or during the morning.

The Tuesday mid-day run of the high-resolution NAM model paints precipitation as rain for the event that starts this evening and continues through tomorrow afternoon (loop from 6pm Tuesday-6pm Wednesday). The chances of wintry precipitation are diminishing as we get closer to the event occurring. 

Precipitation should be departing by rush hour with a cold wind continuing, so roads should also dry out in the evening, precluding the formation of most ice overnight. A few areas, like we saw Sunday morning, could have patchy black ice on Thursday morning, but should not affect 99% of travelers/commuters.

You should still plan on temperatures falling during the day tomorrow. It will likely be in the 50s all night with a strong south wind blowing at 20-30 mph and scattered showers moving in this evening and continuing overnight. With the front arriving around 5-6am, steadier rain is expected for the AM commute with temperatures falling quickly through the 40s during the morning and into the 30s in the afternoon (with wind chills in the 20s). We'll drop to the upper 20s by Thursday morning.


We'll continue to post the latest information on our social media profiles. For snow lovers, you'll be happy to know that the longer-range pattern continues to indicate waves of cold air moving through the region over the next few weeks. Maybe one will collide with some Gulf moisture!

Erik Proseus
MWN Meteorologist

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MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder

Monday, January 21, 2019

A winter reprieve, but another round of "precip" is on horizon!

9:30am Tuesday:  The information for Wednesday has been updated. Please see our social media feeds for the latest. Forecast impacts have decreased since this was published.



Winter definitely made itself known this weekend as light snow brought a coating of white the metro Saturday evening, followed by a sunny but cold day on Sunday with wind chills getting no higher than the 20s. That made for a cold night for viewing the total lunar eclipse last night, but it was still a sight to see anyway!



Monday-Tuesday, warming up

Looking ahead, we'll begin to warm up some today as wind shifts southerly ahead of the next system that arrives Tuesday night in to Wednesday. We'll get into the 40s this afternoon and remain above freezing tonight thanks to increasing southerly flow. Tuesday will be windy with the south wind increasing and gusts likely exceeding 30 mph during the day and overnight. Rain chances also move in by Tuesday late afternoon as highs reach the 50 degree mark. Rain is expected Tuesday night, some of which will likely be heavy.

NWS precipitation totals forecast between 6pm Tuesday and 6pm Wednesday. (via WxBell)

Wednesday, more winter precip

The cold front associated with all that rain arrives in the wee hours of Wednesday. Once again, like Saturday, precipitation will fall behind the front, as will the temperatures. Wednesday's daytime high temperature will be in the upper 30s at dawn with the mercury falling towards the freezing mark, perhaps by the noon hour if not shortly thereafter.

The falling temps mean a complicated forecast as far as precipitation type is concerned on Wednesday. A wintry mix of snow, sleet, and possibly some freezing rain will transition southeast into the metro during the day. There is still disagreement among the models on how fast the cold air arrives and when precipitation moves out.

The Monday morning high-resolution NAM model forecast radar projection for Tuesday evening through Wednesday shows the potential for some winter precipitation on Wednesday. (WeatherModels.com)

What can we expect?

At this time, I expect we could see that wintry mix into areas along and north of I-40 by mid to late morning and south of I-40 by mid-day. With precipitation likely tapering off by mid to late afternoon, ice and snow amounts should not be excessive, but could be a bit problematic, especially in the case of any icing. Temperatures should get close to freezing by midday to early afternoon, so anything that falls before then would melt. After that, all bets are off. We all know that the presence of minor ice amounts can slick up elevated roadways and bridges fairly quickly. And once again, with a transition from rain, there will be no pre-treatment of the roads.

My best educated guess as of now, midday Monday, on amounts and timing (subject to revision of course):

How much: Snow and sleet - less than an inch. Freezing rain/ice - up to 0.10".
When: Transition to a wintry mix between 8am (north, or Tipton County) and 11am (south, or northwest MS) with precip ending by 2-5pm (west to east)
Impacts: Bridges and overpasses could become icy by the lunch hour into the afternoon. Minor accumulations of ice/snow on vehicles and other exposed surfaces (those that you saw snow on Saturday evening).
Confidence: In occurrence of winter precipitation and timing - Medium-High. In exact types and amounts - Medium-Low. In a "bust" scenario, the temperatures stay a bit warmer and we get more rain than wintry precipitation.

At this point, I urge Mid-Southerners to start considering plans for Wednesday, especially afternoon, and monitor the latest forecasts as the situation remains dynamic. The blog will be updated by Tuesday evening with the latest, but monitor our social media feeds for updates as well.



Erik Proseus
MWN Meteorologist

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Follow MWN on Facebook and Twitter for routine updates and the latest info!
Complete MWN Forecast: MemphisWeather.net on the mobile web or via the MWN mobile app
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