SWODY3
SPC AC 180709
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0109 AM CST TUE DEC 18 2007
VALID 201200Z - 211200Z
..THERE IS A SLGT RISK OF SVR TSTMS PORTIONS W-CENTRAL GULF COAST
AND LOWER DELTA REGION...
..SYNOPSIS...
UPPER AIR PATTERN WILL CONTINUE TO BE CHARACTERIZED BY PROGRESSIVE
FLOW AND STG WLY COMPONENT OVER GREAT MAJORITY OF CONUS. SHORTWAVE
TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY W OF NRN CA COAST
INVOF 135W -- IS FCST TO MOVE INLAND DAY-1...AND ACROSS SRN ROCKIES
AND SRN PLAINS DAY-2. PERTURBATION SHOULD TURN EWD AND MOVE ACROSS
SERN CONUS THIS PERIOD...WITH SLOW DEAMPLIFICATION BASED ON MOST
SREF MEMBERS AS WELL AS OPERATIONAL SPECTRAL/WRF. ACCOMPANYING SFC
LOW LIKEWISE IS EXPECTED TO WEAKEN SLOWLY...AS IT MOVES ESEWD FROM
ARKLATEX REGION ALONG DIFFUSE/SYNOPTIC WARM FRONT.
..CENTRAL GULF COAST REGION...
FOR FIRST 6-9 HOURS OF THIS PERIOD...SVR POTENTIAL NEAR COAST WILL
CARRY OVER FROM LATE DAY-2 PERIOD...AS CONTINUATION AND SLGT EWD
SHIFT OF SAME REGIME.
AHEAD OF MID/UPPER TROUGH...VERTICAL WIND PROFILES ARE EXPECTED TO
BE FAVORABLE FOR ORGANIZED SVR OVER BROAD AREA. PRIMARY LIMITING
FACTOR WILL BE MAGNITUDE/EXTENT OF AT LEAST MRGLLY
FAVORABLE/SFC-BASED BUOYANCY INLAND. OPERATIONAL WRF...ALONG WITH
MOST ETA-BMJ MEMBERS OF SREF...APPEAR TOO AGGRESSIVE WITH MOISTURE
RETURN WITH INLAND EXTENT...BASED ON THEIR HISTORICAL TENDENCIES AND
ON OBSERVATIONAL COMPARISON WITH INITIAL MODEL CONDITIONS. PRIND
MOST UNSTABLE BOUNDARY LAYER WILL REMAIN WELL S OF WARM FRONT OVER
GULF...ALTHOUGH FCST SOUNDINGS SUGGEST SLGT INLAND PENETRATION OF
LOW-MID DEW POINTS IS LIKELY EARLY IN PERIOD THAT WILL SUPPORT
EFFECTIVE LIFTED PARCELS BEING ROOTED AT OR VERY NEAR GROUND.
MID/UPPER LEVEL TROUGH IS EXPECTED TO PROGRESS EWD FASTER THAN RATE
OF MARINE AIR MASS MODIFICATION AND DOWNSTREAM ADVECTION CAN
COMPENSATE...IN EFFECT...OUTRUNNING FAVORABLE DESTABILIZATION. NET
RESULT SHOULD BE GEN SEWD TAPERING OF INLAND SVR POTENTIAL FROM
ABOUT 20/18Z ONWARD. ALTHOUGH GREAT VARIATION EXISTS IN PROGGED
MAGNITUDE OF CAPE INLAND...AMONG OPERATIONAL MODELS AS WELL AS SREF
MEMBERS...STRONG MODEL CONSENSUS REASONABLY EXISTS WITH
SEWD-TAPERING TREND IN CAPE PATTERN. NRN EDGE OF CATEGORICAL SLGT
RISK AREA THEREFORE REPRESENTS SOME NEBULOUS TRANSITION FROM
SFC-BASED SVR POTENTIAL -- SUPERCELLS AND SMALL BOWS -- INTO
ELEVATED/ISOLATED HAIL THREAT.
.EDWARDS.. 12/18/2007
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