Wednesday, November 14, 2007

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 141243
SWODY1
SPC AC 141240

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0640 AM CST WED NOV 14 2007

VALID 141300Z - 151200Z

..THERE IS A SLGT RISK OF SVR TSTMS THROUGH THIS EVENING FOR THE
ARKLAMISS INTO MIDDLE TN...

..SYNOPSIS...
A SYNOPTIC SCALE TROUGH OVER THE NRN PLAINS/UPPER MS VALLEY WILL DIG
SEWD TO THE MID MS/OH VALLEYS AND AMPLIFY THROUGH EARLY THURSDAY. A
LARGE SURFACE RIDGE WILL DEVELOP SEWD FROM THE NRN ROCKIES TO THE
SRN HIGH PLAINS IN THE WAKE OF THE MID LEVEL TROUGH...DRIVING A
STRONG COLD FRONT ACROSS THE LOWER MS/TN VALLEYS AND THE
APPALACHIANS. CYCLOGENESIS IS EXPECTED ALONG THE FRONT INVOF THE
NRN MID ATLANTIC/SRN NEW ENGLAND. THE PRIMARY FOCUS FOR
THUNDERSTORM DEVELOPMENT THROUGH THE PERIOD WILL BE THE SURFACE COLD
FRONT FROM THE CENTRAL/SRN APPALACHIANS TO THE LOWER MS VALLEY.

..ARKLAMISS TO NW AL/MIDDLE TN/SRN KY THIS AFTERNOON/EVENING...
THE SURFACE COLD FRONT WILL MOVE ACROSS THIS AREA FROM 18-03Z...IN
PHASE WITH THE DIURNAL CYCLE. INSOLATION WILL WARM SURFACE
TEMPERATURES TO NEAR 70 AS FAR NE AS SRN KY...AND LOWER 80S INTO
AR/MS THIS AFTERNOON. BOUNDARY LAYER DEWPOINTS IN THE LOW-MID 60S
WILL OCCUR IN TANDEM WITH THE WARM AFTERNOON TEMPERATURES. GIVEN
ONLY MODEST MID LEVEL LAPSE RATES NEAR 6.5 C/KM...THE NET RESULT
WILL BE AFTERNOON MLCAPE VALUES OF 500-1000 J/KG.

THUNDERSTORM COVERAGE IS EXPECTED TO INCREASE INVOF THE COLD FRONT
BY MIDDAY IN ASSOCIATION WITH A WEAK LEAD MID LEVEL TROUGH MOVING
ESEWD FROM OK/SRN MO. STORMS WILL PERSIST INTO TONIGHT WHILE
SPREADING EWD/SEWD WITH THE COLD FRONT...THOUGH THE SEVERE STORM
THREAT WILL DIMINISH AS INSTABILITY WANES AFTER SUNSET. FORECAST
SOUNDINGS IN THE WARM SECTOR THIS AFTERNOON SHOW WIND PROFILES
SUPPORTIVE OF SOME SUPERCELL AND/OR EMBEDDED BOWING STRUCTURES. THE
PRIMARY SEVERE STORM THREATS SHOULD BE A FEW DAMAGING WINDS AND
ISOLATED/MARGINAL HAIL...GIVEN THE MODEST INSTABILITY AND LOW-LEVEL
SHEAR /EFFECTIVE SRH GENERALLY AOB 150 M2/S2/.

.THOMPSON/GRAMS.. 11/14/2007

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