SWODY1
SPC AC 231949
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0249 PM CDT THU JUN 23 2011
VALID 232000Z - 241200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE APPALACHIANS/ERN
U.S....
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS SRN KS AND NRN OK EWD TO
THE OZARKS...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE NRN INTERMOUNTAIN
REGION...
...APPALACHIANS/ERN CONUS...
TWO SEPARATE BANDS OF STRONG/LOCALLY-SEVERE STORMS CONTINUE
ATTM...ONE FROM WRN NY/WRN PA SWWD ACROSS OH/WV INTO THE TN
VALLEY...AND A SECOND STRETCHING FROM SRN NEW ENGLAND SWWD ACROSS
THE E COAST STATES TO FL.
WHILE STRONGER FLOW ALOFT REMAINS ACROSS THE NRN PORTION OF THE RISK
AREA...GREATER INSTABILITY IS INDICATED WITH SWD EXTENT.
THEREFORE...CAPE/SHEAR COMBINATION ACROSS THE ENTIRE AREA SUPPORTS
AT LEAST ISOLATED SEVERE POTENTIAL.
...SRN KS/NRN OK EWD TOWARD THE OZARKS...
WEAK/ISOLATED STORMS CONTINUE TO DEVELOP IN THE S CENTRAL KS/NRN OK
VICINITY...BUT LOW-LEVEL JET INCREASE THIS EVENING BENEATH NWLY FLOW
ALOFT COULD SUPPORT DEVELOPMENT OF MORE WIDESPREAD STORMS --
POSSIBLY EVOLVING INTO A SLIGHTLY-ELEVATED/SEWD-MOVING MCS. WITH
AMPLE FLOW ALOFT FOR UPDRAFT ORGANIZATION...WILL MAINTAIN SLIGHT
RISK -- PRIMARILY FOR HAIL -- ACROSS PARTS OF THIS AREA.
...NRN INTERMOUNTAIN REGION...
STORMS CONTINUE TO INCREASE ACROSS MT/ERN ID AND VICINITY...WITHIN
DIFFLUENT UPPER FLOW FIELD AHEAD OF THE MAIN TROUGH. CONTINUED
HEATING/DESTABILIZATION WILL SUPPORT ADDITIONAL STORMS THIS
AFTERNOON/EVENING. WHILE STRENGTH OF FLOW ALOFT IS LIMITED ACROSS
ALL BUT NWRN PORTIONS OF THE SLIGHT RISK AREA...CAPE/SHEAR
COMBINATION SUPPORTS CONTINUATION OF SLIGHT RISK FOR HAIL/WIND
ACROSS THIS REGION.
..GOSS.. 06/23/2011
.PREV DISCUSSION... /ISSUED 1120 AM CDT THU JUN 23 2011/
...SYNOPSIS...
LARGE UPPER LOW OVER GREAT LAKES CONTINUES TO PROVIDE A MDT CYCLONIC
WIND FIELD AS FAR S AS THE TN VALLEY TO MID ATLANTIC STATES. THE
WEAK COLD FRONT DRAPES SWWD ACROSS ERN OH VALLEY TO NRN AR. FURTHER
W SLY FLOW WILL RETURN GULF MOISTURE NWD THRU THE SRN INTO CENTRAL
PLAINS BY TONIGHT. WARM FRONT EXTENDING FROM UPSTATE NY SEWD WILL
ALSO DRIFT SLOWLY EWD THRU THE PERIOD.
BROAD UPPER TROUGH SHIFTS INLAND PAC NW PROVIDING A STRONG CYCLONIC
FLOW INTO NRN INTERMOUNTAIN/NRN ROCKIES. COLD FRONT INTERIOR OR/WA
WILL PUSH EWD INTO WRN MT/SRN ID THIS AFTERNOON PRECEDED BY STEEP
LAPSE RATES AND SUFFICIENT MOISTURE/INSTABILITY FOR SEVERE STORMS.
...ERN STATES...
THE PLUME OF DEEP MOISTURE CURRENTLY SPREADING NEWD ALONG THE
APPALACHIANS HAS REQUIRED A SIGNIFICANT ADJUSTMENT IN THE EXPECTED
AREAS OF SEVERE POTENTIAL FOR THIS AFTERNOON. THE FRONTAL ZONE FROM
ERN OH VALLEY TO TN VALLEY WILL HEAT UP SUFFICIENTLY TO SUPPORT
STRONG/SEVERE THUNDERSTORMS THIS AFTERNOON GIVEN THE 30-40KT OF
SHEAR AND MLCAPES AOA 2000 J/KG.
E OF APPALACHIANS TWO AREAS OF POTENTIAL ORGANIZED STRONG/SEVERE
CONVECTION. WITH A VERY MOIST AND MODESTLY SHEARED
ENVIRONMENT...THE SEA BREEZE FRONT SHOULD BE A FOCUS MID ATLANTIC
COAST FOR A FEW SEVERE STORMS. INLAND EXPECT THE DIFFERENTIAL
HEATING THAT OCCURS ON THE E SIDE OF THE THICKER CLOUDS OVER
APPALACHIANS TO ALSO BE AN AREA OF POSSIBLY MORE ORGANIZED
THUNDERSTORMS AS THE DEEP LAYER SHEAR WILL BE 30-40KT ALONG WITH THE
MDT INSTABILITY.
FURTHER N THE AIR MASS BETWEEN THE COLD FRONT APPROACHING FROM OH
VALLEY AND THE WARM FRONT ERN NY WILL DESTABILIZE WITH HEATING AND
LEAD TO SCATTERED AREAS OF STRONG/SEVERE THUNDERSTORMS. WITH
30-40KT OF SHEAR...STORMS SHOULD DEVELOP INTO CLUSTERS SHORT LINE
SEGMENTS WITH THREAT OF DAMAGING WINDS AND HAIL.
..PORTIONS OF NRN OK/SRN KS INTO SWRN MO/NWRN AR...
THE RISK IS FOR POSSIBLE STORMS TONIGHT...AS STRENGTHENING LOW LEVEL
JET INCREASES WARM ADVECTION/LIFT NORTH OF SURFACE BOUNDARY.
RETURNING GULF MOISTURE WILL LEAD TO PRIMARILY ELEVATED INSTABILITY
FOR INCREASING THUNDERSTORMS OVERNIGHT. STRONGLY VEERING WIND
PROFILES IN MID LEVELS WOULD SUGGEST SUPERCELLS ARE POSSIBLE ALONG
WITH A LARGE HAIL THREAT.
...NRN ROCKIES AREA...
INCREASING DIFFLUENCE ALOFT AND APPROACHING UPPER TROUGH WILL RESULT
IN LARGE SCALE FORCING AND PROVIDE A FAVORABLE ENVIRONMENT FOR
SEVERE STORMS. MUCAPES FROM 1500-2500 J/KG AND
DEEP LAYER SHEAR AROUND 40 KT WILL SUPPORT BOWING SEGMENTS AND
SUPERCELLS WITH WIND DAMAGE AND HAIL BY MID AFTERNOON . STORMS MAY
EVOLVE INTO ONE OR MORE CLUSTERS DURING THE NIGHT... ESPECIALLY
ACROSS CENTRAL/ERN MT...AS SELY LOW LEVEL JET INCREASES.
SUFFICIENT INSTABILITY GIVEN THE VERY STEEP LAPSE RATES AND VEERING
SHEAR PROFILES TO INCLUDE ALL BUT SRN WY IN A SLIGHT RISK OF
SCATTERED THUNDERSTORMS THIS AFTERNOON A FEW WHICH COULD PRODUCE
DAMAGING WINDS AND LARGE HAIL.
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