Monday, December 15, 2008

MESO: Mesoscale Discussion 2473

ACUS11 KWNS 160013
SWOMCD
SPC MCD 160013
KYZ000-TNZ000-ALZ000-MSZ000-MOZ000-ARZ000-LAZ000-TXZ000-OKZ000-160415-

MESOSCALE DISCUSSION 2473
NWS STORM PREDICTION CENTER NORMAN OK
0613 PM CST MON DEC 15 2008

AREAS AFFECTED...ARKLATEX TO MIDDLE TN AND CNTRL KY

CONCERNING...WINTER MIXED PRECIPITATION

VALID 160013Z - 160415Z

SHOWERS OF LIGHT FREEZING RAIN/SLEET SHOULD CONTINUE AND GRADUALLY
SHIFT SEWD...PERHAPS INTENSIFYING THIS EVENING. LIQUID EQUIVALENT
RATES SHOULD LARGELY RANGE FROM 0.05 TO 0.15/3-HR PERIOD.

REPEATED TRAINING OF SHOWERS WITH LIGHT FREEZING RAIN AND SLEET HAVE
OCCURRED OVER THE PAST 6-8 HOURS FROM SERN OK INTO WRN
KY...PRIMARILY DRIVEN BY LOW-LEVEL WARM/MOIST ADVECTION ATOP AN
ARCTIC FRONTAL ZONE. WITH THE SURFACE FRONT /ANALYZED FROM SRN LA TO
ERN TN AT 00Z/ EXPECTED TO SLOWLY SAG SWD WITH CONTINUED CAA N OF
THE BOUNDARY...AXIS OF MIXED PRECIPITATION SHOULD CONCURRENTLY SHIFT
SWD THIS EVENING. BOTH MORNING AND AFTERNOON NAM/GFS/RUC/SREF
GUIDANCE HAVE PERFORMED POORLY WITH RESPECT TO QPF PLACEMENT/TIMING
TODAY. HOWEVER...THEY ARE CONSISTENT WITH STRENGTHING LOW-LEVEL FLOW
THIS EVENING...WHICH WOULD INCREASE ISENTROPIC LIFT AND PERHAPS LEAD
TO ENHANCED PRECIPITATION RATES AMONGST WEAK INSTABILITY /AS SAMPLED
BY 00Z REGIONAL RAOBS/. THIS SCENARIO IS ALSO INDICATED IN 15/00Z
4-KM WRF-NSSL COMPOSITE REFLECTIVITY...WHICH APPEARED TO HAVE A MORE
REALISTIC REPRESENTATION OF ONGOING PRECIPITATION....WITH THE
SUGGESTION OF A GRADUAL SEWD MOVEMENT/INTENSIFICATION OF THE BAND OF
SHOWERS THROUGH 06Z.

..GRAMS.. 12/16/2008

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

...NOTICE...
SPC WINTER WEATHER MESOSCALE DISCUSSIONS WILL BE ISSUED ON A
SCHEDULED BASIS FROM DECEMBER 1 THROUGH FEBRUARY 28...FOUR
TIMES A DAY...AROUND 00 UTC...06 UTC...12 UTC...AND 18 UTC
FOR SIGNIFICANT SHORT RANGE WINTER WEATHER EVENTS.

ATTN...WFO...LMK...OHX...HUN...PAH...MEG...JAN...LZK...SHV...

LAT...LON 33009205 32689364 32809446 33199506 34059495 34979393
35949153 36698940 37418752 37818601 37628526 36848527
35678669 34598847 33529063 33009205

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