FCST: 2/20-22/10 SNOW Northern MO

A potent later winter storm is taking aim on the local area.  Currently an area of low pressure is located in the southwest US.  This area of low pressure is currently located over northern AZ and is forecasted to track into Colorado and weaken.  Another area of low pressure is forecast to form near AMA and track out of the TX panhandle region into the central plains later this evening and into Sunday.  This will be a our next snow producer here in KS-MO.  Here is a look at the current surface chart:

 As the system enters the plains it is going to pull an abundant amount of warm moist air from the Gulf of Mexico.  The storm system and attendant moisture can be seen on the water vapor imagery from this morning:

This storm system is progged to take a classic track for a prolific snow maker for northern Missouri and areas of adjacent Northeast Kansas, Southeastern Nebraska and Southern Iowa.  Remember from the Christmas Eve storm the classic track is basically along and south of the I-44 corridor to near Jefferson City and over to the south of St. Louis.  Here is a look at the progged track of the surface low from HPC:

This setup normally yields very heavy snow accumulations for the local area.  This storm system looks to be no different.  The Gulf of Mexico is indeed wide open and moisture will not be an issue with this storm system.  I agree with Jesse's last post on the snowfall ration being aruond 10:1, which means 1" of rain will produce 10" of snow.  I see no reason to disagree with this ration ATTM.  Here is a look at the QPF for Days 1-3:

  

However, one thing quite concerning is the sharp temperature gradient that will occur with this storm.  This happens many times with late winter storms.  The track of this storm and the strength of the warm air advection ahead of the storm will determine precipitation type.  The model progs are currently forecasting the 540 line to be situated across northern Missouri just south of the US 36 corridor Sunday morning.  The 540 thickness line is a "rough" guide for the transition from rain to snow.  The 850mb and warmest vertical temperature below freezing line is oriented to the north of the 540 thickness line.  In addition, the other critical thickness lines are dissecting the local area along and just south or north of the US 36 corridor.  Here is a look at the on-going Warm Air Advection ahead of the system.  These are the current temps and dewpoints for the region:

Temperatures

Dewpoints

Here is a look at the forecasted temperatures for Sunday morning:

Here is the GFS BUFKIT sounding for KSTJ at 9 a.m. Sunday morning:

The NWS in Pleasant Hill has issued a Winter Storm Warning for Snow effective from 6 p.m. Saturday to Midnight Monday for all of northern Missouri.  The WSW is for snow with accumulations in the 6" to 8" range with locally higher amounts.  Here is a look at the HPC snow fall probabilities:

4" Probabilities

8" Probabilities

 ~ CS ~