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000
ACUS11 KWNS 061732
SWOMCD
SPC MCD 061731
OHZ000-KYZ000-INZ000-TNZ000-ILZ000-MSZ000-MOZ000-ARZ000-062130-

MESOSCALE DISCUSSION 2066
NWS STORM PREDICTION CENTER NORMAN OK
1131 AM CST FRI DEC 06 2013

AREAS AFFECTED...NWRN MS...AR...SRN MO...EXTREME NWRN MS...WRN
TN...WRN AND CNTRL KY...SRN IL...SRN IND...AND SWRN THROUGH CNTRL OH

CONCERNING...WINTER MIXED PRECIPITATION

VALID 061731Z - 062130Z

SUMMARY...A WINTRY MIX OF PRECIPITATION WILL CONTINUE TO AFFECT A
LARGE SWATH OF THE ERN U.S. FROM THE LOWER MS VALLEY INTO PARTS OF
THE TN AND OH VALLEYS. MOSTLY SNOW IS EXPECTED FROM NRN AR...SRN
MO...SRN IL...SRN IND...EXTREME WRN KY THROUGH SWRN AND CNTRL OH
WITH RATES FROM 0.5 TO LOCALLY UP TO 1 INCH AN HOUR. A RELATIVELY
NARROW ZONE OF FREEZING RAIN...POSSIBLY MIXED WITH SLEET SHOULD
PERSIST NEXT SEVERAL HOURS FROM SERN AR...WRN TN...EXTREME NWRN
MS...CNTRL KY AND NCNTRL KY INTO EXTREME SRN OH. FREEZING RAIN RATES
SHOULD RANGE FROM A FEW HUNDREDS OF AN INCH PER HOUR TO OCCASIONALLY
WELL IN EXCESS OF 0.1 INCH PER HOUR.

DISCUSSION...AS OF MID-DAY AN EXPANSIVE AREA OF MIXED PRECIPITATION
EXTENDS FROM NERN TX THROUGH THE LOWER-MID MS VALLEY INTO THE TN AND
OH VALLEYS. THIS WINTRY MIX WAS DEVELOPING WITHIN ZONE OF ISENTROPIC
ASCENT ALONG A SW-NE ORIENTED BAROCLINIC ZONE IN WAKE OF A SFC COLD
FRONT THAT EXTENDS FROM SERN LA NEWD THROUGH THE SRN APPALACHIANS
AND INTO CNTRL/ERN VA. A LARGE AREA OF ARCTIC HIGH PRESSURE IS
BUILDING SEWD...AND THE COLD AIR HAS BECOME DEEP ENOUGH TO SUPPORT
ALL SNOW NORTH OF A LINE FROM CNTRL AR NEWD THROUGH EXTREME WRN KY
AND SRN OH WITH A RELATIVELY NARROW ZONE OF FREEZING RAIN AND SLEET
SOUTH OF THIS LINE. THE NEAR SFC SUBFREEZING AIR IS MORE SHALLOW
ACROSS THE LOWER MS VALLEY REGION...SUPPORTING A BROADER SWATH OF
FREEZING RAIN COMPARED TO FARTHER NE ACROSS THE OH VALLEY.

FRONTOGENETIC FORCING FOR ASCENT AND PRECIPITATION RATES ARE
CURRENTLY MAXIMIZED FROM AR THROUGH WRN TN...SRN MO...WRN KY AND SRN
IL WHERE EXIT REGION OF UPPER JET EJECTING NEWD FROM THE SRN PLAINS
IS COUPLED WITH ENTRANCE REGION OF A POLAR JET LOCATED FROM THE OH
VALLEY INTO THE GREAT LAKES. THIS ZONE OF FORCING FOR ASCENT ALONG
WITH HIGHER PRECIPITATION RATES WILL DEVELOP NEWD THROUGH THE TN AND
OH VALLEYS THIS AFTERNOON. SOME CONVECTIVE ENHANCEMENT WILL REMAIN
LIKELY IN FREEZING RAIN CORRIDOR FROM AR THROUGH WRN TN AND WRN KY
WHERE THE WARM LAYER ALOFT IS MORE PRONOUNCED...RESULTING IN STEEPER
MID LEVEL-LAPSE RATES AND A CONDITIONALLY UNSTABLE LAYER BETWEEN
700-400 MB.

..DIAL.. 12/06/2013

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

ATTN...WFO...RLX...CLE...JKL...ILN...LMK...OHX...IND...PAH...
ILX...MEG...JAN...LSX...LZK...SGF...

LAT...LON   39278237 37158553 35678767 33489105 34189309 36709274
            38798818 40548307 39278237