Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS02 KWNS 210659
SWODY2
SPC AC 210658

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1258 AM CST SUN DEC 21 2014

VALID 221200Z - 231200Z

...THERE IS A MRGL RISK OF SVR TSTMS OVER A PORTION OF LA AND MS...

...SUMMARY...
SHOWERS AND A FEW THUNDERSTORMS WILL BE POSSIBLE FROM THE LOWER
MISSISSIPPI VALLEY INTO THE GULF COAST STATES AND NORTHERN FLORIDA
MONDAY AND MONDAY NIGHT. A MARGINAL RISK FOR A COUPLE OF STRONG TO
SEVERE STORMS WITH A THREAT FOR HAIL AND GUSTY WINDS WILL EXIST
LATER MONDAY NIGHT OVER PORTIONS OF LOUISIANA INTO SOUTHERN
MISSISSIPPI.

...SYNOPSIS...

MODEL CONSENSUS IS THAT SYNOPTIC UPPER TROUGH WILL AMPLIFY FURTHER
OVER THE CNTRL U.S. MONDAY AS STRONG UPPER JET DEVELOPS SWWD INTO
THE CNTRL AND SRN ROCKIES. THE UPPER TROUGH WILL BE ACCOMPANIED BY A
COLD FRONT THAT WILL EXTEND FROM THE UPPER MS VALLEY SWWD THROUGH
ERN TX BY THE END OF THE PERIOD. FARTHER DOWNSTREAM...A WARM FRONT
WILL LIFT NWD INTO TO THE GULF COAST REGION MONDAY NIGHT.

...LOWER MS VALLEY REGION...

THE BOUNDARY LAYER OVER THE GULF WILL CONTINUE TO MODIFY WITH A
BROAD FETCH OF SLY NEAR-SFC WINDS SUPPORTING DEWPOINTS IN THE UPPER
60S TO NEAR 70 F OFFSHORE AND LOW-MID 60S ADVECTING INLAND MONDAY
NIGHT AS WARM FRONT LIFTS NWD. STEEPER MID-LEVEL LAPSE RATES WILL
SPREAD EWD AND EVENTUALLY INTERCEPT WRN FRINGE OF RICHER LOW-LEVEL
MOISTURE FROM SERN TX INTO THE LOWER MS VALLEY WHERE MUCAPE COULD
APPROACH 1500 J/KG MONDAY NIGHT. CAPE WILL REMAIN MARGINAL FARTHER
EAST INTO THE GULF COAST STATES. SLY LLJ WILL STRENGTHEN OVERNIGHT
AS UPPER TROUGH AMPLIFIES...RESULTING IN AN INCREASE IN ISENTROPIC
ASCENT. SHOWERS AND A FEW THUNDERSTORMS SHOULD DEVELOP LATER MONDAY
NIGHT...MOST LIKELY ON THE ERN FRINGE OF THE EML WHERE THE CAP WILL
BE WEAKER FROM A PORTION OF THE LOWER MS VALLEY INTO THE GULF COAST
STATES. STRONG EFFECTIVE BULK SHEAR IN PRESENCE OF AT LEAST MODEST
CAPE RAISES CONCERN FOR AT LEAST A MARGINAL SEVERE RISK. TIME OF DAY
AND LIKELIHOOD THAT RICHER MOISTURE WILL REMAIN OFFSHORE SUGGEST
CONVECTION WILL PROBABLY BE SLIGHTLY ELEVATED ABOVE A STABLE SFC
LAYER. NEVERTHELESS...A FEW STORMS COULD POSE A THREAT FOR MAINLY
HAIL AND POSSIBLY STRONG WIND GUSTS LATER MONDAY NIGHT.

..DIAL.. 12/21/2014



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