Tuesday, October 12, 2010

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 121559
SWODY1
SPC AC 121557

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1057 AM CDT TUE OCT 12 2010

VALID 121630Z - 131200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE LOWER MISSISSIPPI
VALLEY THIS AFTERNOON AND EVENING...

...LOWER MS VALLEY...
THE UPPER LOW THAT HAS BEEN SLOWLY CROSSING THE PLAINS PAST SEVERAL
DAYS WAS LOCATED OVER NWRN AR THIS MORNING. WESTERLIES WILL FINALLY
EXTEND FAR ENOUGH SOUTH TO PICK UP THE LOW AS IT SHEARS AND
ACCELERATES EWD TONIGHT ACROSS THE NRN GULF STATES.

MONDAYS CONVECTIVE ACTIVITY HAS PUSHED A BOUNDARY AND HIGHER THETAE
AIR OFFSHORE CENTRAL GULF COAST...HOWEVER AIR MASS REMAINS
SUFFICIENTLY MOIST/UNSTABLE AHEAD OF THE UPPER LOW FOR ANOTHER ROUND
OF ACTIVE THUNDERSTORMS THIS AFTERNOON.

DAYTIME HEATING COUPLED WITH GRADUALLY COOLING MIDLEVEL TEMPERATURES
AHEAD OF UPPER LOW SHOULD YIELD AN AXIS OF MODERATE INSTABILITY BY
THIS AFTERNOON WITH MLCAPE VALUES APPROACHING 1000-1500 J/KG LWR MS
RIVER VALLEY REGION.

THE BELT OF STRONGEST MIDLEVEL FLOW AND RESULTANT DEEP WLY SHEAR
WILL BE CONFINED TO NEAR AND S OF THE I-20 CORRIDOR WITH FLOW FIELD
DECREASING WITH NWD EXTENT. GIVEN THE MODEST DESTABILIZATION
ANTICIPATED BY AFTERNOON...SETUP WILL BE SUPPORTIVE OF ORGANIZED
STORM MODES...INCLUDING MULTI- AND SUPERCELL STRUCTURES WITH A RISK
FOR DAMAGING WIND GUSTS AND HAIL INTO TONIGHT.


...MID ATLANTIC COAST...
THERE WILL STILL BE SOME POTENTIAL FOR ISOLATED STORM DEVELOPMENT
THIS AFTERNOON OVER PARTS OF ERN MD...DE..SERN PA AND SRN NJ ALONG
COLD FRONT SLOWLY SAGGING SEWD THROUGH THE AREA. BASED ON 12Z
PIT/IAD OBSERVATIONS AND MODEL FORECAST SOUNDINGS VALID THIS
AFTERNOON...ENVIRONMENT WILL FEATURE MODESTLY STEEP LAPSE
RATES...WEAK CONVECTIVE INSTABILITY AND MODERATELY
STRONG...UNIDIRECTIONAL WNWLY TROPOSPHERIC FLOW. AS SUCH...A THREAT
FOR ISOLATED STRONG WIND GUSTS AND PERHAPS SOME HAIL WILL BE
POSSIBLE WITH ANY STORMS THAT CAN DEVELOP AND BECOME SUSTAINED LATER
TODAY.

..HALES/GARNER.. 10/12/2010

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