AREAS AFFECTED...E-CNTRL MO...CNTRL IL...W-CNTRL INDIANA
CONCERNING...HEAVY SNOW
VALID 241652Z - 242145Z
SUMMARY...SNOW WITH RATES OF 1-2 IN/HR AND OCCASIONAL THUNDERSNOW
WILL CONTINUE SPREADING EWD/ENEWD THROUGH THE AFTERNOON.
DISCUSSION...E-CNTRL IL INTO W-CNTRL INDIANA:
THE BULK OF HIGH-RESOLUTION WRF GUIDANCE AND COARSER-RESOLUTION
MESOSCALE/GLOBAL GUIDANCE CONTINUE TO BE UNDERDOING THE STRENGTH OF
WARM-CONVEYOR-RELATED PRECIP LEADING A SRN-MO DEEP CYCLONE PER WATER
VAPOR IMAGERY. CONVECTIVE PROCESSES -- ILLUSTRATED BY RELATIVELY
REDUCED CONVECTIVE STABILITY PROFILES SAMPLED BY AMDAR DATA FOR
FLIGHT PATHS CROSSING THE WARM CONVEYOR BELT -- ARE GREATLY
ENHANCING PRECIP RATES WITHIN THE WARM CONVEYOR BELT. AS THIS PRECIP
BECOMES SUPERIMPOSED WITH DEEP SUB-FREEZING THERMAL PROFILES
DOWNSTREAM ACROSS E-CNTRL IL AND W-CNTRL INDIANA...HEAVY SNOW WILL
OVERSPREAD THESE AREAS IN THE 1730Z-2000Z TIME FRAME. SNOW RATES OF
1-2 IN/HR WILL BE LIKELY...AS HAS BEEN OBSERVED UPSTREAM ACROSS
PARTS OF THE MID MS VALLEY. ELEVATED BUOYANCY SHOULD BE SUFFICIENT
FOR A FEW INSTANCES OF THUNDERSNOW...ESPECIALLY INVOF OF THE
INTERSTATE 70 CORRIDOR WHERE THE CONVECTIVE ENHANCEMENT WILL BE MORE
ROBUST OWING TO RELATIVELY WARMER 800-700-MB TEMPERATURES/INFLOW
BASES PER AMDAR DATA/FORECAST SOUNDINGS. SNOW RATES OF 2 IN/HR WILL
BE MOST LIKELY WITH THUNDERSNOW.
E-CNTRL MO INTO CNTRL IL:
HEAVY SNOW IS ONGOING...IMPACTING AREAS AROUND ST. LOUIS...WITH
SEVERAL REPORTS OF THUNDERSNOW. BANDS OF HEAVY SNOW WILL LIKELY
CONTINUE THROUGH THE AFTERNOON AS AN ENE/WSW-ORIENTED DEFORMATION
ZONE N/NW OF THE DEEPER CYCLONE CONTINUES TO OFFER FRONTOGENETIC
ASCENT AMIDST A SUFFICIENT SUPPLY OF DEEPER MOISTURE EMANATING FROM
THE WARM CONVEYOR STRUCTURE.
..COHEN.. 03/24/2013
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...IND...LOT...ILX...LSX...
LAT...LON 40858749 40078703 39508750 38908926 38589026 38389108
38719163 39229156 40149036 41018846 40858749
