This is my updated forecast for Wednesday night and Thursday

–  This event is an ideal case study for something called isentropic analysis as discussed in the lmk discussion Tuesday morning. Basically mapping different pressure levels can show pressure and moisture advection at a certain pressure level. where these advections of moisture and pressure are occurring lift happens which produces overrunning precipitation. Looking at the pressure lines closely there’s already a ripple over eastern Tex/Ark forming.

take a look at current 290 K pressure level map. We’re on the backside of the high so advections come from the southwest.

the green areas are mixing ratios another measure of atmospheric moisture while the red lines represent pressure. the advection of higher moisture and pressure into a colder airmass leads to ideal overrunning event even with a very weak low such as this one.

– this overrunning precipitation develops tomorrow late afternoon across the central part of the state and moves east. A gradual change from snow and sleet to ice and even rain should occur depending on location.

map 1: maximum northern position of 32*F line.

Wednesday evening

Thursday 12 am- 6am

Thursday 6 am-noon

overall .25 to .75 of liquid should fall. My own quick isentropic analysis indicated the heaviest precipitation should fall from e-town to Jackson. This is the mean of the gfs( south) and Nam (north) so I have good forecast confidence in the highest totals falling along that line with lighter amounts on each side.

updated forecast

three zones to make the text easier to read

C: quick glaze of ice under 2/10th’s  to rain maybe a touch of snow or sleet at the start


Northern section: Lexington, Louisville: temp only reaches 32, an inch or so of snow and sleet then around 1/2 inch ice

Southern section:   up to 1 inch of snow and sleet then around 1/2 inch of ice, temps get to 33 or 34* for a few hours.

A: snow and some ice: 2-6 of snow and sleet with light icing possible.

other notes:

– Looking at the maps one might think a storm should in the deep south sat but the shortwave coming out of the southwest and the old frontal boundary from this system never really phase to form a storm till it is well east of the region. The ECMWF has been showing this for several runs now.

– more cold and snow shower chances early next week

– one more shot of more substantial snow just before christmas

-white-o-meter @ 6/10, 7/10 for the southeast.

– still looking for the pattern flip to extreme warmth as in the winter forecast but still not showing up to much in the ECMWF weeklies or in the teleconnections yet.



  1. tommy Says:

    wow, this is a big deal….thanks for the update mitch! i dig your blog!

  2. trent Says:

    temps alreday a bust tonight due to models not recognizing snowpack, could that have anything to do with the moels not recognizing the cold air for this storm

  3. Seth Says:

    12z nam colder. Several inches of snow possible for areas Lexington and Louisville points north according to that run.

    You might want to come back up to Versailles for this event Mitch! 🙂

  4. james Says:

    Mitch, I saw the same thing as Seth. Your thoughts?

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