SPC MD 49

MD 0049 CONCERNING FREEZING RAIN FOR PORTIONS OF NORTH CENTRAL-NERN MO…SOUTH CENTRAL-SERN IA AND FAR WEST CENTRAL IL


MESOSCALE DISCUSSION 0049
NWS STORM PREDICTION CENTER NORMAN OK
0236 AM CST SUN JAN 27 2013

AREAS AFFECTED...PORTIONS OF NORTH CENTRAL-NERN MO...SOUTH
CENTRAL-SERN IA AND FAR WEST CENTRAL IL

CONCERNING...FREEZING RAIN

VALID 270836Z - 271230Z

SUMMARY...LIGHT FREEZING RAIN WITH RATES OF 0.05 INCH/2-3 HR IS
EXPECTED TO DEVELOP AND MOVE ENEWD OVER PORTIONS OF NORTH
CENTRAL-NERN MO INTO SOUTH CENTRAL-SERN IA BETWEEN 09-12Z...AND THEN
AFFECT FAR WEST CENTRAL IL AFTER 12Z. THE DURATION OF THIS FREEZING
RAIN ACROSS THE DISCUSSION AREA SHOULD BE SHORT-LIVED /1-2
HOURS/...GIVEN A RELATIVELY SMALL BREADTH OF THE PRECIPITATION BAND
PER REGIONAL RADAR IMAGERY. THE SURFACE TEMPERATURE ACROSS THE WRN
HALF OF THE IA AND MO PORTIONS OF THE DISCUSSION AREA SHOULD RISE
ABOVE 32 F BETWEEN 13-15Z...AND THUS END THE FREEZING RAIN THREAT IN
THOSE REGIONS.

DISCUSSION...00Z SOUNDINGS INDICATED THE LOWER TROPOSPHERE WAS
INITIALLY DRY OVER NRN MO/SRN IA WITH 06-08Z SURFACE OBSERVATIONS
STILL INDICATING 15 DEGREE SURFACE DEWPOINT DEPRESSIONS. AT 08Z...
REGIONAL RADAR IMAGERY SHOWED A SOMEWHAT NARROW BAND OF LIGHT
PRECIPITATION EXTENDING FROM SRN NEB EWD THEN SEWD THROUGH ERN KS
AND FAR NWRN TO SWRN MO. ALTHOUGH SURFACE TEMPERATURES OVER SOUTH
CENTRAL IA INTO THE WRN PART OF THE DISCUSSION AREA /FROM KCDG TO
KCOU/ ARE ABOVE 32 F...EVAPORATIVE COOLING ALONG THE LEADING EDGE OF
THE PRECIPITATION BAND SHOULD RESULT IN TEMPERATURES FALLING BELOW
32 F. TRENDS IN SURFACE WET BULB TEMPERATURES PER OBJECTIVE ANALYSES
CONFIRM THIS SCENARIO AS THE 32 F WET BULB ISOTHERM HAS BEEN
ADVANCING VERY SLOWLY NEWD SINCE 0330Z...AND CURRENTLY RESIDES FROM
THE IA/NEB BORDER THROUGH NWRN TO SERN MO. MEANWHILE...00Z UPPER AIR
ANALYSES INDICATED TEMPERATURES OVER SRN IA/NRN MO WERE ALREADY
ABOVE 0 C AT THE 925 MB AND 850 MB LEVELS...WITH THESE TEMPERATURES
RANGING FROM +2 TO 4 C. THE 00Z 850 MB TEMPERATURE IN FAR WEST
CENTRAL IL WAS ALSO ABOVE 0 C.

AN INCREASE IN DEEP LAYER ASCENT WITHIN THE EXIT REGIONS OF SWLY LOW
LEVEL AND MID LEVEL JETS IMPINGING ON NRN MO/SRN IA INTO THE EARLY
MORNING WILL AID IN MAINTAINING THE ONGOING BAND OF PRECIPITATION AS
IT ADVANCES ENEWD. 06Z RAP SUGGESTS THE AIR MASS WILL BECOME
SUFFICIENTLY MOISTENED BY 10-11Z ACROSS MUCH OF THE DISCUSSION AREA
WITH FREEZING RAIN THE PRIMARY PRECIPITATION TYPE...ADVANCING INTO
FAR WEST CENTRAL IL BY 12Z.

..PETERS.. 01/27/2013

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...LSX...DVN...DMX...EAX...

LAT...LON   39989335 40479399 41159460 41389346 41299267 40999190
            40239112 39249058 38889089 39029183 39599290 39989335

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