Wednesday, January 12, 2022

Another winter weather event? Looking ahead to the MLK weekend...

Barely two weeks into 2022, just removed from the warmest December in over 130 years, and we're already looking at the third winter weather event of 2022! Let's start with the wrap-up to this week first.

End of the week

High pressure that brought chilly weather early this week has scooted off to our east, so now air is wrapping clockwise around it and bringing us warmer air from our south. We'll top out near 60 degrees today with mostly sunny skies. As the high continues to move east and away from us, it opens the door to a couple of weak systems that move through Thursday and early Friday. Those systems turn our wind around to the west and then northeast. For Thursday, more sunshine and above normal temps in the upper 50s, but Friday sees more high clouds and cooler highs near 50 (still seasonal though). Lows will remain above freezing.

Progression of surface weather features across the country from Wednesday evening through Friday evening. A couple of weak troughs (brown dashed lines) move through the Mid-South Thursday otherwise dry weather is expected. Also note the major weather system diving  south from the northern plains towards the end of the loop.... (NWS)

Saturday and Sunday

A somewhat unusual track for a low pressure system that will affect the Mid-South materializes by late in the week and into Saturday. You'll notice in the loop above that a big red L (low pressure) and series of fronts dives south from the northern plains towards the region by Friday night. With an upper level trough forming over the eastern U.S., it is basically "digging" into that trough and moving south. This weekend, it merges with a low ejecting out of the southern plains into the Lower Mississippi Valley, then heads back northeast and up the eastern seaboard. A strong upper level low pressure system accompanies it, providing the lift and vigorous dynamics, while the low pulls moisture up from the south. A recipe for winter shenanigans...

So while it is too early to focus on specific details, some high level information can be gleaned from this setup, as well as what needs to come together (or not if you are a snow-hater) for winter weather to materialize. First, the ingredients for a significant snowfall somewhere in the region are becoming more apparent. Confidence is increasing that by the end of the weekend, some places in the larger Mid-South area (say southern MO, western KY, AR into west TN, or north MS) will see a fairly major snow event, given we're in Dixie - on the order of multiple inches. The unknowns are mainly "where" and "how much." 

The Winter Weather Severity Index (WSSI) forecasts where winter storm impacts are expected out to 4 days in advance. As of Wednesday afternoon, the Memphis area is in a "Minor Impacts" zone, which means we would see an "inconvenience to daily life." That could change as we get closer to the event and the area of highest impact becomes more obvious. (NWS)

We'll start the day Saturday with increasing rain chances as the low pressure drops south towards the area. It will also be cold with temperatures mainly in the upper 30s to near 40. As the upper level pressures start to fall, along with the precipitation and onset of darkness Saturday evening, the atmosphere will cool. With temperatures falling through the 30s and the low level thermal profile cooling as well, rain will likely begin changing to snow overnight and could come down steadily to heavy at times through the night. 

Again, the *where* is the true unknown right now and will depend heavily on the track of the surface and upper level low pressure systems. The northwest quadrant of the surface low, near the upper low, is typically favored for heaviest snow. If the surface low goes overhead, the heaviest snow will fall to our north. If it shifts to our south, we could be positioned in the "sweet spot." Models are spitting out some fairly impressive totals, but the location varies between models and with each model run. For now, the possibility exists for a few inches or more somewhere in the region, but may not be known until the day of the event. Lingering light snow on the backside of the system seems likely Sunday, especially early in the day, with temperatures remaining in the lower half of the 30s all day. Whatever falls likely sticks around into Monday.

The European model ensemble (in essence, the European model produced 50 times with slightly different parameters) produces these probabilities for at least one inch of snow through Sunday at 6pm. Memphis is right around 50%. (WeatherBell)

As usual, we'll have you stay in touch for more details! We'll be posting updates at least daily, especially on Facebook and Twitter, over the coming 48-72 hours. In the meantime, be a smart "sharer" of winter weather information!

Erik Proseus
MWN Meteorologist

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