MD 0050 CONCERNING FREEZING RAIN FOR CENTRAL AND ERN IA/FAR NERN MO/WEST CENTRAL AND FAR NWRN IL/PART OF SOUTH CENTRAL-SERN MN/FAR SWRN WI
MESOSCALE DISCUSSION 0050
NWS STORM PREDICTION CENTER NORMAN OK
0640 AM CST SUN JAN 27 2013
AREAS AFFECTED...CENTRAL AND ERN IA/FAR NERN MO/WEST CENTRAL AND FAR
NWRN IL/PART OF SOUTH CENTRAL-SERN MN/FAR SWRN WI
CONCERNING...FREEZING RAIN
VALID 271240Z - 271745Z
SUMMARY...FREEZING RAIN WILL CONTINUE TO DEVELOP AND SPREAD NEWD
ACROSS CENTRAL...NRN AND ERN IA...FAR NERN MO AND WEST CENTRAL IL
THROUGH 15Z...AND THEN REACH PARTS OF SOUTH CENTRAL AND SERN
MN...FAR SWRN WI AND FAR NWRN IL BETWEEN 14-18Z. THE GREATEST
FREEZING RAIN RATES SHOULD RANGE FROM 0.05-0.1 INCH PER HR. BY LATE
MORNING...A SUBSTANTIAL INCREASE IN LOW LEVEL WAA MAY ALLOW SURFACE
TEMPERATURES FROM SOUTH OF DSM TO FAR SERN IA...WEST CENTRAL IL AND
FAR NERN MO TO RISE ABOVE 32 F...ENDING THE FREEZING RAIN THREAT IN
THOSE AREAS.
DISCUSSION...AT 12Z...REGIONAL RADAR IMAGERY INDICATED A 90 MILE
WIDE BAND OF PRECIPITATION EXTENDING FROM NWRN IA THROUGH SOUTH
CENTRAL AND SERN IA INTO ERN MO WITH SURFACE OBSERVATIONS INDICATING
A MIX OF FREEZING RAIN AND POSSIBLY SLEET...FREEZING DRIZZLE AND/OR
SNOW IN SOME LOCATIONS. HOWEVER...ONCE THE LOWER TROPOSPHERE BECOMES
SATURATED AIDED BY EVAPORATIVE COOLING AND A WARMING IN THE 800-900
MB LAYER BECOMES MORE PRONOUNCED PER WAA...FREEZING RAIN SHOULD
BECOME THE PRIMARY PRECIPITATION TYPE. THIS THREAT WILL INITIALLY BE
A CONCERN FROM NORTH CENTRAL...CENTRAL AND SERN IA INTO FAR NERN MO
AND WEST CENTRAL IL. RECENT RADAR IMAGERY ALSO SHOWED A NEW AREA OF
PRECIPITATION DEVELOPING/EXPANDING IN AREAL COVERAGE OVER NERN KS
INTO SERN NEB. THIS ACTIVITY MAY BE ATTENDANT TO STRONGER DEEP LAYER
ASCENT WITHIN THE EXIT REGION OF A 50-60 KT SWLY MIDLEVEL JET
ACCOMPANYING THE CENTRAL HIGH PLAINS SHORTWAVE TROUGH.
FARTHER NE AND N...12Z SOUNDINGS AT DVN/MPX SHOWED DRY AIR REMAINING
IN THE LOWER TROPOSPHERE. GIVEN SURFACE DEWPOINTS ARE IN THE TEENS
ACROSS ERN IA/NWRN IL/SWRN WI AND SRN MN...EVAPORATIVE COOLING
SHOULD HELP TO MAINTAIN SURFACE TEMPERATURES BELOW 32 F THIS MORNING
AND SUPPORT FREEZING RAIN AS THE PREDOMINANT PRECIP TYPE.
AN INCREASE IN DEEP LAYER ASCENT IS EXPECTED ACROSS THE DISCUSSION
AREA THIS MORNING AS DPVA WITH THE SHORTWAVE TROUGH MOVES INTO THIS
REGION AND LOW LEVEL WAA STRENGTHENS ALONG THE NOSE OF 40-50 KT SWLY
LLJ EXPECTED TO EXTEND INTO SRN IA BY 18Z. THESE FACTORS SHOULD AID
IN INCREASING PRECIPITATION RATES AND GIVEN THE STRENGTHENING LLJ
INTO SRN IA...FORECAST SOUNDINGS SHOW A STRONG WARM NOSE ABOVE THE
SUB FREEZING SURFACE TEMPERATURES.
..PETERS.. 01/27/2013
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...ILX...MKX...LSX...DVN...ARX...MPX...DMX...EAX...
FSD...
LAT...LON 40939335 42049436 43319529 43939478 43989180 43139069
42329019 41418996 40259015 39649081 40369253 40939335
via SPC Forecast Products http://www.spc.noaa.gov/products/md/md0050.html
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