SPC MESOSCALE DISCUSSION 0030 FOR NWRN/NCNTRL AR
CONCERNING...WINTER MIXED PRECIPITATION...

VALID 182345Z - 190200Z

A MIXTURE OF SLEET...SNOW AND SOME FREEZING RAIN IS EXPECTED TO
DEVELOP OVER NWRN INTO NCNTRL AR DURING THE NEXT FEW HOURS. 
FREEZING RAIN SHOULD BE CONFINED TO VALLEY LOCATIONS WHERE SUB-
FREEZING AIR MAY BE TRAPPED.  ONCE THE MIXED PRECIPITATION
BEGINS...IT SHOULD PERSIST FOR AT LEAST 3-4 HOURS.

REGIONAL RADARS SHOW A LARGE AREA OF STEADY LIGHT TO MODERATE
PRECIPITATION OVER ERN OK MOVING INTO NWRN AR.  SURFACE
OBSERVATIONS INDICATE TEMPERATURES IN THE MIDDLE 30S F FROM NWRN
INTO NCNTRL AR WITH SURFACE WET-BULB TEMPERATURES AT OR JUST BELOW
32 F.  VERTICAL THERMAL STRATIFICATION FROM THE ETA/RUC BOTH
INDICATE WARMING IN THE 850-700 MB LAYER TO JUST ABOVE 0 C.  ONCE
THE BOUNDARY LAYER BECOMES SATURATED THROUGH THE PROCESS OF
EVAPORATIVE COOLING AND SOME MELTING EFFECTS FROM MODERATE
PRECIPITATION RATES...PRECIPITATION SHOULD CHANGE FROM SLEET/SNOW
OVER TO MAINLY SLEET.  A FEW VALLEY LOCATIONS MAY HAVE SLEET MIXED
WITH FREEZING RAIN. 

..PETERS.. 01/18/02