Continuing to monitor the Christmas snow potential - Saturday update

Snow is really cool in the Mid-South, especially since we don't see it much (it's been over 380 days since we last got "measurable snowfall.")  It's even more fun when it falls on Christmas Day, as a White Christmas is even more rare. Yesterday we began discussing a Christmas Day storm system that has the potential to bring a layer of white to the Memphis metro.  This post is just a quick update to that one.

To sum it up, computer models still indicate a strong possibility of rain on Christmas afternoon changing to snow on Christmas night here in the metro and points north.  Low pressure (which is currently off the coast of the Pacific Northwest) will move through the Rockies and head across the Southern Plains before turning northeast, tapping into Gulf moisture, and passing just to our south.  With plenty of moisture to work with and cold air moving in behind the low, we have the classic setup for snow in the Mid-South.  As mentioned yesterday, the arrival of sufficient cold air and remaining moisture have to coincide.

According to the most recent mid-range model data, which is remaining fairly consistent on the big picture, the changeover to snow would occur sometime after 6pm and before midnight Christmas night with precipitation tapering off after midnight (on Wednesday).  So while the window of opportunity is somewhat narrow, it's definitely there.  Below is this morning's computer model data from the GFS model.  The morning European model is similar, with slightly higher amounts on the AR side of the Mississippi River.  Total snowfall amounts from both models are somewhere in the 1-4" range.

The 12Z (morning) model run of the GFS shows anywhere from 1-4" of snow on Christmas night in the metro.  This is NOT a forecast, but one possibility from one run of a computer model.

Remember that guidance from the models can and will change many times between now and Tuesday.  However, there is sufficient confidence in the overall pattern to include the possibility of accumulating snow in the forecast.  If you have travel plans Christmas night or Wednesday, especially north of the metro, keep a close eye on the forecast and remain flexible.  We'll continue to monitor and keep you updated!

"I'm dreaming of a White Christmas... "

Erik Proseus
Meteorologist, MemphisWeather.net

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