MESO: Mesoscale Discussion 0465

ACUS11 KWNS 140809
SWOMCD
SPC MCD 140808
WIZ000-IAZ000-MNZ000-141145-

MESOSCALE DISCUSSION 0465
NWS STORM PREDICTION CENTER NORMAN OK
0308 AM CDT SUN APR 14 2013

AREAS AFFECTED...SRN MN...FAR NERN IA...SWRN WI

CONCERNING...FREEZING RAIN

VALID 140808Z - 141145Z

SUMMARY...SHIELD OF PRECIPITATION LIFTING NEWD ACROSS IA MAY LEAD TO
A PERIOD OF FREEZING RAIN WITH RATES AOA 0.02 IN/HR OVER SRN MN.
ADDITIONAL SHOWERS ARE DEVELOPING FROM SRN MN INTO SWRN MN AND NERN
IA...WHICH MAY ALSO BE ASSOCIATED WITH THE OCCURRENCE OF FREEZING
RAIN WITH TIME.

DISCUSSION...AREA VWP/S AND PROFILERS SHOW A 60+ KT LOW-LEVEL SSWLY
JET DEVELOPING OVER THE CNTRL PLAINS THIS MORNING. MEANWHILE...A
TIGHT BAROCLINIC ZONE AT 850 MB EXTENDS FROM SD SEWD ACROSS IA INTO
IL. THE INCREASING LLJ ACTING ON THIS TEMPERATURE GRADIENT IS
YIELDING STRONG LOW-LEVEL WAA AND SHOWER DEVELOPMENT...WHICH IS
SPREADING NWD TOWARD SRN MN INTO SWRN WI. AT THE SURFACE...THE WET
BULB FREEZING LINE EXTENDS FROM CNTRL SD EWD INTO FAR SRN MN AND SRN
WI. TEMPERATURES ABOVE THE COLD SURFACE AIRMASS ARE CURRENTLY BELOW
FREEZING /PER RAP AND OBJECTIVE ANALYSIS GUIDANCE/. HOWEVER...WAA
ABOVE THE SURFACE IS FORECAST TO BOOST TEMPERATURES IN THE 850-700
MB LAYER TO SLIGHTLY ABOVE FREEZING DURING THE NEXT FEW HOURS. AS
THIS OCCURS IN CONJUNCTION WITH SHOWERS OVER THE AREA...THE THREAT
FOR FREEZING RAIN IS EXPECTED TO INCREASE DURING THE MORNING...WITH
RATES EXCEEDING 0.02 IN/HR.

..GARNER.. 04/14/2013

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

ATTN...WFO...MKX...ARX...MPX...FSD...

LAT...LON 43478954 43009032 43499248 43769423 43719599 43949633
44409613 44579532 44489300 44179125 43478954

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