DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 181937
SWODY1
SPC AC 181935

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0235 PM CDT THU OCT 18 2012

VALID 182000Z - 191200Z

...NO SVR TSTM AREAS FORECAST...

...APPALACHIANS INTO THE MID-ATLANTIC...
A CLUSTER OF STORMS HAS FORMED OVER WV...NEAR THE FRONT AND WHERE
AREAS OF HEATING HAVE CONTRIBUTED TO DESTABILIZATION. ALTHOUGH
MOISTURE IS MINIMAL...DEWPOINTS WILL BE GRADUALLY INCREASING INTO
THE MID 50S F. DEEP LAYER SHEAR IS FAVORABLE FOR A FEW SUPERCELLS
CAPABLE OF MARGINALLY SEVERE HAIL AND GUSTY WINDS. FOR MORE
INFORMATION SEE MESOSCALE DISCUSSION 2076.

LATER THIS EVENING AND OVERNIGHT...LOW PRESSURE IS FORECAST TO FORM
OVER VA IN RESPONSE TO THE UPPER JET MAX DEVELOPING NEWD ENHANCING
LIFT. THIS MAY RESULT IN ADDITION STORMS FORMING MAINLY FROM VA NEWD
INTO ERN PA/NJ WHERE WARM ADVECTION WILL BE STRONGEST. GIVEN
MARGINAL INSTABILITY...ONLY ISOLATED SEVERE WIND GUSTS OR A BRIEF
WEAK TORNADO ARE EXPECTED.

...LOWER RIO GRANDE VALLEY...
STRONG HEATING CONTINUES OVER DEEP S TX WITH TEMPERATURES IN EXCESS
OF 100 F. ACCORDING TO MODIFIED SOUNDINGS...THIS SHOULD RESULT IN
MINIMAL CIN WITH ISOLATED THUNDERSTORMS POSSIBLE AS THE FRONT DRIFTS
S. RECENT SATELLITE IMAGERY SHOWS CU NEAR THE SEA BREEZE AND
ADDITIONALLY S OF THE RIVER. THE INTERSECTION OF THE FRONT AND THESE
CU BANDS MAY EVENTUALLY YIELD ISOLATED THUNDERSTORMS CAPABLE OF HAIL
AND WIND.

..JEWELL.. 10/18/2012

.PREV DISCUSSION... /ISSUED 1121 AM CDT THU OCT 18 2012/

...SYNOPSIS...
AN OCCLUDING DEEP-LAYER CYCLONE WILL BE CENTERED OVER THE UPPER MS
VALLEY TODAY...WITH A SERIES OF SHORTWAVE TROUGHS ROTATING E-NEWD
AROUND THE CYCLONE THROUGH THE FORECAST PERIOD. ONE WAVE POSITIONED
OVER THE MID/UPPER OH VALLEY THIS MORNING WILL LIFT NWD ACROSS THE
GREAT LAKES REGION DURING THE AFTERNOON...WHILE A SECOND WAVE EXITS
THE GREAT PLAINS AND MOVES INTO THE CNTRL APPALACHIANS BY TONIGHT.
MEANWHILE...A SURFACE COLD FRONT ASSOCIATED WITH THE PRIMARY UPPER
LOW WILL PROGRESS EWD TOWARD THE ATLANTIC COAST...WHILE THE SWWD
EXTENSION OF THE FRONT OVER THE NRN GOM AND FAR S TX SLOWLY SAGS
SWD. LATE THIS AFTERNOON AND TONIGHT...SECONDARY SURFACE
CYCLOGENESIS MAY OCCUR ALONG THE COLD FRONT OVER THE
CAROLINAS/MID-ATLANTIC IN RESPONSE TO AN EJECTING SHORTWAVE TROUGH.

...UPPER OH VALLEY/LOWER GREAT LAKES INTO THE CAROLINAS THIS
AFTERNOON AND TONIGHT...
MORNING RAOBS FROM THE UPPER OH VALLEY/LOWER GREAT LAKES REGION INTO
THE CAROLINAS INDICATE VERY POOR LAPSE RATES ARE PRESENT AHEAD OF
THE COLD FRONT. IN ADDITION...MODEL GUIDANCE/FORECAST SOUNDINGS SHOW
LOW POTENTIAL FOR STRONG DESTABILIZATION LATER THIS AFTERNOON. WITH
SURFACE DEWPOINTS THIS AFTERNOON RANGING FROM THE LOW 50S OVER PA TO
MID 60S IN THE ERN CAROLINAS...MUCAPE VALUES WILL GENERALLY BE BELOW
500-1000 J/KG. THIS ENVIRONMENT WILL SUPPORT THE DEVELOPMENT OF LINE
SEGMENTS AND STORM CLUSTERS ALONG THE COLD FRONT THIS
AFTERNOON/TONIGHT AS LARGE-SCALE ASCENT ASSOCIATED WITH THE NEXT
SHORTWAVE TROUGH APPROACHES. STRONG DEEP-LAYER SHEAR MAY AID IN THE
DEVELOPMENT OF EMBEDDED BOWING STRUCTURES AND ISOLATED DAMAGING WIND
GUSTS. HOWEVER...WEAK INSTABILITY WILL GREATLY LIMIT THE SVR WEATHER
THREAT.

OVER THE CAROLINAS INTO PORTIONS OF THE MID-ATLANTIC...WEAK SURFACE
CYCLOGENESIS IS FORECAST TO OCCUR IN THE LEE OF THE CNTRL
APPALACHIANS LATER THIS AFTERNOON...WITH THE LOW PROGRESSING N-NEWD
TOWARD MD TONIGHT. ISOLATED THUNDERSTORMS MAY FORM WITHIN A LEE-SIDE
CONVERGENCE ZONE THIS AFTERNOON OVER THE WRN/CNTRL CAROLINAS AND VA.
MODEST INSTABILITY AND STRONG MID/UPPER-LEVEL WIND FIELDS MAY
SUPPORT AN ISOLATED DAMAGING WIND THREAT OR BRIEF TORNADO.

CLUSTERS OF THUNDERSTORMS ARE FORECAST TO DEVELOP LATE THIS
AFTERNOON AND EVENING OVER COASTAL NC...AND THEN LIFT NWD INTO SERN
MD/SRN DE DURING THE NIGHT. SURFACE WINDS MAY REMAIN BACKED IN
RESPONSE TO A WEAK LEE-SIDE SURFACE LOW LOCATED INLAND...AND VEER TO
S-SWLY IN THE 1-3 KM AGL LAYER. THIS VEERING WIND PROFILE WILL YIELD
MODEST LOW-LEVEL VERTICAL WIND SHEAR...AND AID IN AN ISOLATED
TORNADO/DAMAGING WIND THREAT.

FROM SC INTO THE FL PANHANDLE...A VERY MARGINAL THREAT FOR A
DAMAGING WIND GUST EXISTS THIS AFTERNOON AS ISOLATED STORM CLUSTERS
FORM/PERSIST ALONG/AHEAD OF THE COLD FRONT.

...DEEP SOUTH TX...
SURFACE TEMPERATURES ARE FORECAST TO WARM INTO THE 90S THIS
AFTERNOON OVER DEEP SOUTH TX. THIS HEATING WILL AID IN ERODING A
LOW-LEVEL INVERSION OBSERVED IN THE 12Z BRO RAOB. IN
ADDITION...DEWPOINTS IN THE 60S LOCATED ALONG AND S OF A COLD FRONT
WILL CONTRIBUTE TOWARD MLCAPE VALUES NEAR 2000 J/KG. GIVEN THE
PRESENCE OF THIS AIRMASS COMBINED WITH A CONVERGENT SURFACE FLOW
REGIME...ISOLATED THUNDERSTORMS WILL BE POSSIBLE. STEEP LOW-LEVEL
LAPSE RATES AND FAVORABLE MOISTURE AND BUOYANCY WILL AID IN AN
ISOLATED DAMAGING WIND/LARGE HAIL THREAT THIS AFTERNOON/EVENING.

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