MESO: Mesoscale Discussion 0023

ACUS11 KWNS 170850
SWOMCD
SPC MCD 170850
ILZ000-IAZ000-MOZ000-171315-

MESOSCALE DISCUSSION 0023
NWS STORM PREDICTION CENTER NORMAN OK
0250 AM CST MON JAN 17 2011

AREAS AFFECTED...SOUTH CENTRAL AND SERN IA/FAR NORTH CENTRAL AND
NERN MO

CONCERNING...FREEZING RAIN

VALID 170850Z - 171315Z

LIGHT SNOW WILL CONTINUE TO DEVELOP FROM W-E ACROSS THE DISCUSSION
AREA. WINTRY PRECIPITATION IS EXPECTED TO TRANSITION TO SLEET BY
09-10Z ACROSS S CENTRAL IA/FAR N CENTRAL MO...AND THEN TO FREEZING
RAIN BY 12Z. SLEET AND EVENTUALLY FREEZING RAIN SHOULD DEVELOP OVER
SERN IA AND FAR NERN MO BETWEEN 12-15Z. FREEZING RAIN RATES ACROSS
THE ENTIRE DISCUSSION AREA WILL BE AT LEAST 0.05 IN/3 HR WITH VALUES
UP TO 0.1 IN/3 HR POSSIBLE.

A MIDLEVEL SHORTWAVE TROUGH...CURRENTLY TRACKING SEWD ACROSS SWRN
MN/NWRN IA...WILL MOVE INTO CENTRAL IA BY 12Z...BEFORE MOVING MORE
ENEWD LATER THIS MORNING. WIND PROFILERS/WSR-88D VADS SHOWED A 40
KT SWLY LLJ EXTENDING FROM KS INTO WRN IA. AT THE SURFACE...
TEMPERATURES ACROSS SRN IA/FAR NRN MO ARE EXPECTED TO REMAIN
SUB-FREEZING INTO THE EARLY MORNING. MEANWHILE...TEMPERATURES IN
THE 850-900 MB LAYER WILL CONTINUE TO INCREASE TO ABOVE 0 C THROUGH
15Z ACROSS THE DISCUSSION AREA AS THE AFOREMENTIONED LLJ TRANSLATES
EWD INTO IA/NRN MO. THIS ABOVE GROUND WARM LAYER WILL SUPPORT THE
TRANSITION IN PRECIP TYPES TO SLEET AND THEN FREEZING RAIN. UPWARD
VERTICAL MOTION ATTENDANT TO THE SHORTWAVE TROUGH/VORT AND STRONG
LOW LEVEL WAA AS THE LLJ STRENGTHENS TO 50 KT BY 12Z SHOULD SUPPORT
AN INCREASE IN PRECIPITATION COVERAGE...AS INDICATED BY RECENT
TRENDS IN REGIONAL RADAR IMAGERY OVER WRN/CENTRAL IA.

..PETERS.. 01/17/2011

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

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

LAT...LON 41919348 41719242 41339172 40989135 40509130 40299179
40139269 40249358 40379397 40959420 41919348

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