SPC AC 192156
DAY 1 CONVECTIVE OUTLOOK CORR 1
NWS STORM PREDICTION CENTER NORMAN OK
0456 PM CDT SAT JUN 19 2010
VALID 192000Z - 201200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE NRN HIGH PLAINS SEWD
ACROSS THE MO VALLEY...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE
SOUTHEAST/GULF COAST STATES...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE
NORTHEAST...
CORRECTED SLIGHT RISK LINE ACROSS IA
...NRN HIGH PLAINS SEWD ACROSS THE MO VALLEY REGION...
ONGOING MCS CONTINUES MOVING ESEWD ACROSS MO ATTM...AND WITH
UNSTABLE AIRMASS AHEAD OF THIS SYSTEM...EXPECT THREAT FOR DAMAGING
WINDS AND SOME HAIL TO CONTINUE OVER THE NEXT FEW HOURS.
MEANWHILE...FORECAST FOR REDEVELOPMENT FARTHER NW REMAINS ON
TRACK...WITH INITIAL CONVECTION DEVELOPING OVER THE HIGH PLAINS OF
ERN WY ATTM. ADDITIONAL DEVELOPMENT IN THIS REGION SHOULD
EVENTUALLY ORGANIZE/MOVE ESEWD...WITH ASSOCIATED THREAT FOR DAMAGING
WINDS INTO THE EVENING.
LATER...STORMS SHOULD DEVELOP/INCREASE IN THE KS/NEB VICINITY NEAR
AND N OF OUTFLOW-ENHANCED SURFACE FRONT...AS STRONG SLY LOW-LEVEL
JET DEVELOPS THIS EVENING. ALONG WITH THREAT FOR HAIL...RELATIVELY
WIDESPREAD DAMAGING WIND THREAT IS EXPECTED AS STORMS ORGANIZE INTO
ONE OR MORE MCSS ACROSS THIS REGION...SHIFTING SEWD THROUGH THE
OVERNIGHT HOURS.
...THE GULF COAST STATES...
WIDESPREAD CONVECTION IS ONGOING ACROSS PARTS OF THE SOUTHEAST/GULF
COAST STATES...INCLUDING A LOOSELY-ORGANIZED BOWING MCS PROGRESSING
SWD ACROSS NWRN GA/CENTRAL AL ATTM. EXPECT POTENTIAL FOR ISOLATED
DAMAGING WINDS TO CONTINUE ACROSS A LARGE PORTION OF THE SOUTHEAST
THROUGH EARLY EVENING...PARTICULARLY IN CONJUNCTION WITH THE
EVOLVING MCS.
...THE NORTHEAST...
MODEST DESTABILIZATION CONTINUES ACROSS THE NORTHEAST AHEAD OF THE
SHORT-WAVE TROUGH CROSSING THE GREAT LAKES REGION...AND ASSOCIATED
SURFACE FRONT MOVING INTO THE LOWER GREAT LAKES ATTM. STORMS HAVE
BEGUN TO INCREASE FROM NY SWWD ACROSS WRN PA INTO ERN OH/WRN
WV...AND EXPECT THIS TREND TO CONTINUE OVER THE NEXT COUPLE OF
HOURS. GIVEN THE AMPLE INSTABILITY AND SUFFICIENT FLOW ALOFT...A
FEW STRONGER STORMS/STORM CLUSTERS WILL BE CAPABLE OF ISOLATED WIND
DAMAGE.
..GOSS.. 06/19/2010
.PREV DISCUSSION... /ISSUED 1125 AM CDT SAT JUN 19 2010/
...SYNOPSIS...
TROUGH REMAINS OVER NWRN U.S. WITH BROAD RIDGING CENTRAL U.S. AND
FLAT TROUGH MOVING THRU NERN STATES. A WEAK COLD FRONT WILL PASS
ACROSS THE LOWER GREAT LAKES LATER THIS AFTERNOON AND EVENING.
LARGE SCALE OUTFLOW FROM FRIDAY MCS ACTIVITY OVER OH VALLEY HAS
SWEPT SEWD AND THIS AM EXTENDS FROM ERN KY/TN WSWWD TO NRN MS.
ADDITIONAL CONVECTIVE OUTFLOW TRAILS WSWWD FROM THE CURRENT LATEST
SVR MCS OVR NERN KS INTO SERN CO.
A VERY WARM/HUMID AND POTENTIALLY STRONGLY UNSTABLE AIR MASS RESIDES
S OF OUTFLOW BOUNDARIES FROM SRN PLAINS EWD TO ATLANTIC COAST.
...CENTRAL PLAINS TO LOWER MO VALLEY...
ONCE AGAIN TODAY A SEVERE MCS IS TRACKING EWD ALONG THE SRN FRINGE
OF THE STRONGER WESTERLIES THAT EXTEND ACROSS NRN/CENTRAL PLAINS.
THIS SEVERE MCS THAT ORIGINATED LAST NIGHT OVER SWRN NEB HAS
DEVELOPED A STRONG COLD POOL AND WELL DEFINED REAR INFLOW JET AND
SHOULD CONTINUE TO PROPAGATE E/ESEWD AS LONG AS THE SUPPLY OF VERY
MOIST/UNSTABLE AIR MASS IS AVAILABLE. CURRENTLY MLCAPES AS SAMPLED
BY THE 12Z TOP SOUNDING ARE GREATER THAN 4000 J/KG INTO WRN MO...AND
AS THE AIR MASS RECOVERS EWD ACROSS MO IN THE WAKE OF THE DOWNSTREAM
BOUNDARY...NOW EXPECT THE DERECHO TYPE SYSTEM TO AT LEAST MAKE IT TO
MS RIVER BY LATER THIS AFTERNOON.
AGAIN IN THE WAKE OF THIS CURRENT SYSTEM...UPSLOPE AND LOW LEVEL
CONVERGENCE COUPLED WITH STRONG HEATING...SHOULD SET THE STAGE FOR
YET ANOTHER SEVERE MCS BY THIS EVENING BACK IN THE GENESIS ZONE OF
THE CENTRAL HIGH PLAINS. IN THE EARLY STAGE LATE THIS
AFTERNOON...IN THE UPSLOPE ZONE OF SWRN NEB/NERN CO SUPERCELLS
ALONG WITH THREAT OF VERY LARGE HAIL AND ISOLATED TORNADOES ARE
LIKELY...AGAIN EVOLVING INTO A DAMAGING WIND EVENT SIMILAR TO THE
CURRENT MCS AS THE LOW LEVEL JET RAMPS UP THIS EVENING TO 40KT OR
SO.
HAVE EXTENDED THE SEVERE POTENTIAL NWD INTO WRN SD AS LOW LEVEL
MOISTURE RETURN ON THE SELY FLOW WILL BE SUFFICIENT TO DEVELOP
MLCAPES AOA 1000 J/KG WHICH COUPLED WITH STEEP LAPSE RATES AND 40-50
KT OF SHEAR SHOULD LEAD TO AT LEAST AN ISOLATED SUPERCELL POTENTIAL
INCLUDING LARGE HAIL.
...SERN STATES...
HAVE INCREASED THE WIND DAMAGE POTENTIAL ACROSS THE INLAND GULF
COAST STATES AS THE OUTFLOW BOUNDARY MOVING SWD INTERACTS WITH A
VERY MOIST AND UNSTABLE AIR MASS. WHILE SHEAR IS GENERALLY LESS
THAN 15 KT THE ENHANCED LOW LEVEL CONVERGENCE ALONG THE BOUNDARY
ALONG WITH SBCAPE TO 4000 J/KG SUPPORTS DOWNBURST WIND DAMAGE IN THE
PULSE STORM ENVIRONMENT.
.LWR GRT LKS/NRN APPALACHIANS...
WITH LARGELY UNIMPEDED SFC HEATING...SUFFICIENT DESTABILIZATION IS
OCCURRING /SBCAPE OF 1500-2000 J PER KG/ TO SUPPORT SCTD STRONG
STORMS ALONG AND AHEAD OF FRONT FROM WV/WRN PA NEWD INTO UPSTATE NY.
COUPLED WITH 30-40 KT DEEP WLY FLOW AHEAD OF UPR TROUGH...SETUP MAY
FOSTER A FEW SUSTAINED MULTICELL BANDS/CLUSTERS. BOWING SEGMENTS
AND ANY MORE ROBUST STORMS WITHIN THIS ACTIVITY COULD YIELD DMGG
WIND AND MARGINALLY SVR HAIL. THE SVR THREAT COULD MOVE/DEVELOP AS
FAR NE AS NRN NEW ENGLAND BY EARLY EVE.
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