Winter Weather

SATURDAY STORM UPDATE

Update Wed 07:41 PM — Today’s models don’t show any significant changes with the forecast.  However, the timeframe (84 hours) of the storm now falls into the range of the NAM and SREF models.  With these higher resolution models, we have the following trends:

Snow starts perhaps a bit later, about 11 AM.  Heavier precip starts early afternoon.  A changeover or mix with sleet starts as early as 3-4 PM.

But it may not be a straight progression towards rain- several models, especially the NAM and CMC have the precipitation rate increasing enough about 5-6 PM that dynamic cooling occurs and a mix back to snow may occur despite surface temperatures rising above 32º.

Here’s a 3 frame gif of the precipitation type at 1PM 4PM and 7 PM–

This afternoon’s NAM Snow-sleet rain prediction at 1PM, 4 PM, and 7 PM Saturday.  White line is 32º surface temp line. Blue snow, pink sleet, green rain, red -freezing rain. 

Snow accumulations are still in the 1-2.5 inch range.

The storm significantly tapers and ends about 9 PM.

Once we get into the 48 hour time frame, we’ll have a better handle on the timing and fine points.

Update Wed 07:21 AM — Last night’s models continue a similar forecast as yesterday: Snow begins between 9-10 AM Saturday and mixes with and changes to rain late Saturday afternoon 3-6 PM.

The GFS GEFS and CMC are somewhat similar with a 2 or so inch  snowfall before being tamped down by sleet and rain.  The ECMWF is still coming in with about 1 inch or less.  Keep in mind:  the models have over-estimated snow totals so far this year.

Here’s a change:  Precipitation now ends about 8 PM, according to the GFS.

This morning’s GEFS snow depth totals

The storm is just in the 90-95 hour forecast period.  By later today, it will fall into the range of some of the higher resolution models, the SREF and the NAM.

I’ll update this evening.