[BNAWX] Severe Storm Outlook Narrative

[EMWIN Server]

ACUS11 KWNS 221813
SWOMCD
SPC MCD 221812
KYZ000-TNZ000-ILZ000-MOZ000-ARZ000-MSZ000-OKZ000-TXZ000-222215-

MESOSCALE DISCUSSION 2564
NWS STORM PREDICTION CENTER NORMAN OK
1212 PM CST WED DEC 22 2004

AREAS AFFECTED...SERN OK...CENTRAL/NRN AR...FAR SERN MO...FAR SRN
IL...FAR WRN KY...WRN/NWRN TN

CONCERNING...WINTER MIXED PRECIPITATION

VALID 221812Z - 222215Z

HEAVY SNOW WILL DEVELOP NEWD FROM SERN OK INTO N-CENTRAL/NRN AR
...FAR SERN MO...FAR SRN IL...AND WRN KY THIS AFTERNOON INTO EARLY
THIS EVENING. FREEZING RAIN AND SLEET IS LIKELY MUCH OF THIS
AFTERNOON FROM CENTRAL AR ENEWD INTO SWRN TN.

AT 1730Z...ELONGATED FRONTAL ZONE EXTENDED FROM PARENT CYCLONE OVER
WRN QUEBEC SWWD ACROSS THE OH/TN VALLEYS TO A SECONDARY LOW NEAR THE
TX UPPER COAST. THIS LOW WILL TRACK NEWD TO SWRN MS BY 00Z...WITH
CONTINUED ADVECTION OF DRY POLAR LOW-LEVEL AIR ACROSS THE SRN PLAINS
EWD INTO THE MID-MS RIVER VALLEY.

IMPRESSIVE 500MB TROUGH AND ASSOCIATED 80KT JET MAX WILL ROTATE EWD
ACROSS NRN/CENTRAL TX THROUGH 00Z. COUPLED 300MB JET STRUCTURE
BECOMES WELL ESTABLISHED ACROSS AR NEXT SEVERAL HOURS...AS DOES
MID-LEVEL PVA LEADING TO DEEP LAYER VERTICAL MOTION FROM SERN OK
NEWD ACROSS CENTRAL/NRN AR INTO THE LOWER OH RIVER VALLEY BY EARLY
TONIGHT. IN ADDITION...SYSTEM IS TAPPING AMPLE GULF MOISTURE AND
MARGINAL INSTABILITY LEADING TO IMPRESSIVE PRECIPITATION SHIELD THAT
SHOULD EXPAND NWD OVER SUBFREEZING AIR ACROSS NRN AR EWD TO WRN KY
DURING NEXT 6 HOURS. FRONTOGENETIC FORCING IS PROGGED TO BECOME
BETTER ESTABLISHED NEWD FROM UPPER TROUGH ACROSS NRN AR INTO FAR
SERN MO AND NWRN TN/WRN KY LEADING TO REDEVELOPMENT OF MODERATE TO
HEAVY SNOW ACROSS ERN PORTIONS OF THIS AXIS LATE THIS AFTERNOON INTO
EARLY EVENING. SNOW RATES OF 1"/HR APPEAR LIKELY ACROSS THIS REGION
FOR AT LEAST SEVERAL HOURS.

STRENGTHENING ISENTROPIC ASCENT ACROSS CENTRAL AR INTO WRN TN SHOULD
RESULT IN FAVORABLE PROFILES FOR FREEZING RAIN OR SLEET THIS
AFTERNOON FROM LIT EWD TO MEM AND ADJACENT AREAS JUST TO THE NORTH.
18Z SOUNDING FROM LIT INDICATES ABOVE FREEZING LAYER FROM 850-750MB.
SHALLOW NEAR-SURFACE COLD ADVECTION IS LIKELY...HOWEVER...COOLING
ALOFT IS UNLIKELY UNTIL MID-LEVEL TROUGH MOVES OVERHEAD EARLY THIS
EVENING.

RUC SOUNDINGS THIS AFTERNOON INDICATE ELEVATED INSTABILITY WHICH
SHOULD RESULT IN HEAVY FREEZING RAIN/SLEET AND POSSIBLE
THUNDERSTORMS. DESPITE INTENSE PRECIPITATION RATES...MARGINAL GROUND
TEMPERATURES MAY LIMIT EXTENT OF SURFACE ICING ALTHOUGH SOME THREAT
SHOULD EXIST ON ELEVATED ROADS AND STRUCTURES.

..BANACOS.. 12/22/2004

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

...NOTICE...
SPC WINTER WEATHER MESOSCALE DISCUSSIONS WILL BE ISSUED ON A
SCHEDULED BASIS...FOUR TIMES A DAY...BETWEEN 00-01 UTC...
06-07 UTC...12-13 UTC...AND 18-19 UTC AS SIGNIFICANT SHORT
RANGE WINTER WEATHER EVENTS UNFOLD.  THIS SCHEDULE WILL BE
USED FROM DECEMBER 1 THROUGH FEBRUARY 28.

ATTN...WFO...OHX...PAH...MEG...LZK...SGF...SHV...TSA...

35979293 36958989 37478839 37168766 36438772 36188778
35508897 35048992 34729061 34349176 34159374 33919477
33899515 34079537 34549530 35349432 35939295

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