MESO: Mesoscale Discussion 0024

ACUS11 KWNS 171236
SWOMCD
SPC MCD 171235
ILZ000-IAZ000-MOZ000-171700-

MESOSCALE DISCUSSION 0024
NWS STORM PREDICTION CENTER NORMAN OK
0635 AM CST MON JAN 17 2011

AREAS AFFECTED...SERN IA...EXTREME NERN MO AND PART OF NWRN IL

CONCERNING...WINTER MIXED PRECIPITATION

VALID 171235Z - 171700Z

A TRANSITION FROM LIGHT SNOW TO SLEET AND LIGHT FREEZING RAIN IS
EXPECTED TO OCCUR FROM W-E THIS MORNING. THIS TRANSITION IN
PRECIPITATION TYPE IS EXPECTED OVER SERN IA AND EXTREME NERN MO
THROUGH 15Z...AND THEN INTO PART OF NWRN IL BETWEEN 15-18Z.
PRECIPITATION RATES HAVE BEEN GENERALLY AOB 0.05 IN/3HR...THUS
FAR...ACROSS SRN IA...WITH LOCALIZED TOTAL AMOUNTS UP TO 0.1 INCH.
GIVEN THE LACK OF GREATER MOISTURE ADVECTION INTO THE MID-UPPER MS
VALLEY...SIMILAR RATES SHOULD OCCUR THIS MORNING ACROSS THE
DISCUSSION AREA.

EARLY MORNING WATER VAPOR IMAGERY SHOWED A SHORTWAVE TROUGH LOCATED
ACROSS SRN MN INTO CENTRAL IA...WITH THIS FEATURE EXPECTED TO TRACK
ENEWD INTO WI/FAR NRN IL BY MID DAY. 40-50 KT SWLY LLJ EXTENDING
FROM CENTRAL KS TO CENTRAL IA PER 11Z WIND PROFILERS/WSR-88D VAD
WILL SHIFT EWD THIS MORNING AND SHOULD EXTEND FROM NERN MO TO NRN
IL/SERN WI AND LAKE MI BY 18Z. DEEP LAYER ASCENT ATTENDANT TO THE
SHORTWAVE TROUGH AND STRONG LOW LEVEL WAA ALONG THE LLJ WILL SUPPORT
THE PRECIPITATION SHIELD SPREADING ENEWD ALONG THE TRACK OF THIS
SYSTEM.

10Z RUC REMAINS CONSISTENT WITH EARLIER MODELS SUGGESTING THE
PORTION OF THE 850 MB 0 C LINE IN IA/IL WILL MOVE NEWD CONCURRENT TO
THE EWD SHIFT OF THE LLJ THIS MORNING...AND SHOULD EXTEND FROM 30 W
CID-5 NNE MLI-10 WNW DEC BY 18Z. THE LOCATION OF THE LLJ THROUGH
THE MORNING IS EXPECTED TO DELINEATE THE AREA RECEIVING THE GREATEST
POTENTIAL FOR SLEET AND LIGHT FREEZING RAIN...AS THE CONTINUED
INCREASE IN TEMPERATURES IN THE 850-900 MB LAYER ATOP SUB-FREEZING
SURFACE TEMPERATURES SUPPORT AN INITIAL TRANSITION TO SLEET AND THEN
MAINLY LIGHT FREEZING RAIN.

..PETERS.. 01/17/2011

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

ATTN...WFO...LOT...ILX...DVN...DMX...EAX...

LAT...LON 40429325 41339308 41519241 41609135 41828979 41438913
40599016 40419137 40429325

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