DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0747 AM CDT WED MAR 23 2011
VALID 231300Z - 241200Z
...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON/EVENING FOR
CENTRAL/ERN KY...SRN OH...AND CENTRAL/WRN WV...
...THERE IS A SLGT RISK OF SVR TSTMS FOR MUCH OF THE TN/OH VALLEY
REGION EWD TO THE MID ATLANTIC COAST...
...SYNOPSIS...
A MIDLEVEL TROUGH OVER IA/SRN MN THIS MORNING WILL PROGRESS ESEWD TO
THE OH VALLEY THIS AFTERNOON AND THE MID ATLANTIC REGION BY EARLY
THURSDAY...WHILE AN ASSOCIATED 90-110 KT MIDLEVEL JET DEVELOPS EWD
OVER TN/KY THIS AFTERNOON AND THE CAROLINAS TONIGHT. AT THE
SURFACE...A CYCLONE IN CENTRAL IL THIS MORNING WILL MOVE EWD TO OH
THIS AFTERNOON...PRIOR TO DEVELOPMENT OF A NEW CYCLONE OFF THE MID
ATLANTIC COAST OVERNIGHT. A COLD FRONT/REMNANT DRYLINE WILL MOVE
EWD/SEWD ACROSS THE OH/TN VALLEY REGION THROUGH THIS EVENING IN
CONJUNCTION WITH THE SURFACE CYCLONE...AND THEN APPROACH THE SE
ATLANTIC COAST BY 24/12Z. THE AREA NEAR THE SURFACE
CYCLONE...ALONG/E OF THE COLD FRONT/DRYLINE...AND W OF THE
APPALACHIANS...WILL EXPERIENCE THE PRIMARY SEVERE STORM THREATS
TODAY.
...OH/TN VALLEYS EWD TO THE ATLANTIC COAST THROUGH TONIGHT...
A SWATH OF 55-60 F BOUNDARY LAYER DEWPOINTS IS SPREADING NEWD FROM
MS/AL/TN/AR TOWARD THE OH VALLEY ON A 40-50 KT WSWLY LLJ. THIS
MOISTURE WILL COMBINE WITH DAYTIME HEATING AND 8 C/KM MIDLEVEL LAPSE
RATES N OF THE JET CORE TO SUPPORT MODERATE INSTABILITY /MLCAPE
VALUES AROUND 1500 J PER KG/ IN THE WARM SECTOR THIS AFTERNOON.
CONVECTIVE INHIBITION WILL WEAKEN BY MIDDAY OVER A RATHER BROAD
AREA...AND MULTIPLE BANDS OF THUNDERSTORMS ARE EXPECTED TO DEVELOP
BY EARLY AFTERNOON. THOUGH LOW-LEVEL FLOW IS EXPECTED TO WEAKEN
SOME AND VEER TO MORE WLY DURING THE DAY...DEEP-LAYER VERTICAL SHEAR
AND STRAIGHT HODOGRAPHS WILL BE FAVORABLE FOR BOTH SPLITTING
SUPERCELLS AND FAST-MOVING LINE SEGMENTS.
THE COLD MIDLEVEL TEMPERATURES /NEAR -20 C AT 500 MB/...STEEP LAPSE
RATES...AND SUPERCELL WIND PROFILES APPEAR SUPPORTIVE OF A
RELATIVELY WIDESPREAD THREAT FOR LARGE HAIL...SOME OF WHICH COULD BE
SIGNIFICANT. DAMAGING WINDS CAN ALSO BE EXPECTED AS A RESULT OF
HIGH MOMENTUM /35-50 KT/ FLOW IN THE LOWEST FEW KM AGL...IN
COMBINATION WITH STEEP LOW-LEVEL LAPSE RATES. THE TORNADO THREAT IS
LESS CERTAIN GIVEN THE LIMITED LOW-LEVEL HODOGRAPH CURVATURE...BUT A
FEW TORNADOES WILL STILL BE POSSIBLE GIVEN THE LIKELIHOOD OF
MULTIPLE SUPERCELLS OVER A BROAD AREA THIS AFTERNOON/EVENING.
THUNDERSTORMS WILL ALSO SPREAD E OF THE APPALACHIANS LATE THIS
AFTERNOON INTO TONIGHT AS THE SYNOPTIC SYSTEM PROGRESSES EWD/ESEWD.
STRONG WIND PROFILES WILL CONTINUE...BUT LESSER INSTABILITY COMPARED
TO AREAS W OF THE MOUNTAINS SHOULD RESULT IN A GRADUAL LESSENING OF
THE DAMAGING WIND/HAIL THREAT OVERNIGHT TOWARD THE ATLANTIC COAST.
THE SRN EXTENT OF THE SEVERE STORM THREAT IS SOMEWHAT UNCERTAIN.
DEEP-LAYER VERTICAL SHEAR WILL BE VERY STRONG BENEATH THE JET CORE
AS FAR S AS NRN AL...WHERE BOUNDARY LAYER DEWPOINTS SHOULD REMAIN
NEAR 60 F. MIDLEVEL LAPSE RATES WILL BE MUCH LESS FAVORABLE
COMPARED TO AREAS FARTHER N...ON THE CYCLONIC SIDE OF THE JET...AND
THIS WILL LIMIT CAPE. STILL...THE STRONG WIND PROFILES AND
SUBSTANTIAL LOW-MIDLEVEL BUOYANCY COULD SUPPORT STORMS WITH DAMAGING
WINDS.
..THOMPSON/GRAMS.. 03/23/2011
NWS STORM PREDICTION CENTER NORMAN OK
0747 AM CDT WED MAR 23 2011
VALID 231300Z - 241200Z
...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON/EVENING FOR
CENTRAL/ERN KY...SRN OH...AND CENTRAL/WRN WV...
...THERE IS A SLGT RISK OF SVR TSTMS FOR MUCH OF THE TN/OH VALLEY
REGION EWD TO THE MID ATLANTIC COAST...
...SYNOPSIS...
A MIDLEVEL TROUGH OVER IA/SRN MN THIS MORNING WILL PROGRESS ESEWD TO
THE OH VALLEY THIS AFTERNOON AND THE MID ATLANTIC REGION BY EARLY
THURSDAY...WHILE AN ASSOCIATED 90-110 KT MIDLEVEL JET DEVELOPS EWD
OVER TN/KY THIS AFTERNOON AND THE CAROLINAS TONIGHT. AT THE
SURFACE...A CYCLONE IN CENTRAL IL THIS MORNING WILL MOVE EWD TO OH
THIS AFTERNOON...PRIOR TO DEVELOPMENT OF A NEW CYCLONE OFF THE MID
ATLANTIC COAST OVERNIGHT. A COLD FRONT/REMNANT DRYLINE WILL MOVE
EWD/SEWD ACROSS THE OH/TN VALLEY REGION THROUGH THIS EVENING IN
CONJUNCTION WITH THE SURFACE CYCLONE...AND THEN APPROACH THE SE
ATLANTIC COAST BY 24/12Z. THE AREA NEAR THE SURFACE
CYCLONE...ALONG/E OF THE COLD FRONT/DRYLINE...AND W OF THE
APPALACHIANS...WILL EXPERIENCE THE PRIMARY SEVERE STORM THREATS
TODAY.
...OH/TN VALLEYS EWD TO THE ATLANTIC COAST THROUGH TONIGHT...
A SWATH OF 55-60 F BOUNDARY LAYER DEWPOINTS IS SPREADING NEWD FROM
MS/AL/TN/AR TOWARD THE OH VALLEY ON A 40-50 KT WSWLY LLJ. THIS
MOISTURE WILL COMBINE WITH DAYTIME HEATING AND 8 C/KM MIDLEVEL LAPSE
RATES N OF THE JET CORE TO SUPPORT MODERATE INSTABILITY /MLCAPE
VALUES AROUND 1500 J PER KG/ IN THE WARM SECTOR THIS AFTERNOON.
CONVECTIVE INHIBITION WILL WEAKEN BY MIDDAY OVER A RATHER BROAD
AREA...AND MULTIPLE BANDS OF THUNDERSTORMS ARE EXPECTED TO DEVELOP
BY EARLY AFTERNOON. THOUGH LOW-LEVEL FLOW IS EXPECTED TO WEAKEN
SOME AND VEER TO MORE WLY DURING THE DAY...DEEP-LAYER VERTICAL SHEAR
AND STRAIGHT HODOGRAPHS WILL BE FAVORABLE FOR BOTH SPLITTING
SUPERCELLS AND FAST-MOVING LINE SEGMENTS.
THE COLD MIDLEVEL TEMPERATURES /NEAR -20 C AT 500 MB/...STEEP LAPSE
RATES...AND SUPERCELL WIND PROFILES APPEAR SUPPORTIVE OF A
RELATIVELY WIDESPREAD THREAT FOR LARGE HAIL...SOME OF WHICH COULD BE
SIGNIFICANT. DAMAGING WINDS CAN ALSO BE EXPECTED AS A RESULT OF
HIGH MOMENTUM /35-50 KT/ FLOW IN THE LOWEST FEW KM AGL...IN
COMBINATION WITH STEEP LOW-LEVEL LAPSE RATES. THE TORNADO THREAT IS
LESS CERTAIN GIVEN THE LIMITED LOW-LEVEL HODOGRAPH CURVATURE...BUT A
FEW TORNADOES WILL STILL BE POSSIBLE GIVEN THE LIKELIHOOD OF
MULTIPLE SUPERCELLS OVER A BROAD AREA THIS AFTERNOON/EVENING.
THUNDERSTORMS WILL ALSO SPREAD E OF THE APPALACHIANS LATE THIS
AFTERNOON INTO TONIGHT AS THE SYNOPTIC SYSTEM PROGRESSES EWD/ESEWD.
STRONG WIND PROFILES WILL CONTINUE...BUT LESSER INSTABILITY COMPARED
TO AREAS W OF THE MOUNTAINS SHOULD RESULT IN A GRADUAL LESSENING OF
THE DAMAGING WIND/HAIL THREAT OVERNIGHT TOWARD THE ATLANTIC COAST.
THE SRN EXTENT OF THE SEVERE STORM THREAT IS SOMEWHAT UNCERTAIN.
DEEP-LAYER VERTICAL SHEAR WILL BE VERY STRONG BENEATH THE JET CORE
AS FAR S AS NRN AL...WHERE BOUNDARY LAYER DEWPOINTS SHOULD REMAIN
NEAR 60 F. MIDLEVEL LAPSE RATES WILL BE MUCH LESS FAVORABLE
COMPARED TO AREAS FARTHER N...ON THE CYCLONIC SIDE OF THE JET...AND
THIS WILL LIMIT CAPE. STILL...THE STRONG WIND PROFILES AND
SUBSTANTIAL LOW-MIDLEVEL BUOYANCY COULD SUPPORT STORMS WITH DAMAGING
WINDS.
..THOMPSON/GRAMS.. 03/23/2011
