Monday, April 26, 2010

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 260525
SWODY1
SPC AC 260523

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1223 AM CDT MON APR 26 2010

VALID 261200Z - 271200Z

...THERE IS A SLGT RISK OF SVR TSTMS TODAY OVER S FL...

...SYNOPSIS...

MIDLEVEL TROUGH AXIS INITIALLY EXTENDING FROM A VORTICITY MAXIMUM
OVER THE UPPER OH VALLEY SWD INTO THE ERN GULF OF MEXICO WILL PIVOT
NEWD THROUGH THE ATLANTIC SEABOARD IN ADVANCE OF AN INTENSIFYING
UPSTREAM SYSTEM DIGGING SEWD INTO THE MID MS VALLEY.

IN THE LOW LEVELS...A SURFACE LOW ASSOCIATED WITH THE FORMER FEATURE
WILL DEVELOP EWD FROM THE UPPER OH VALLEY INTO THE DELMARVA BY THIS
EVENING WHILE AN ASSOCIATED COLD FRONT STRENGTHENS WHILE PROGRESSING
EWD FROM THE APPALACHIANS. FARTHER W...ANOTHER COLD FRONTAL SEGMENT
WILL SURGE SWD INTO CNTRL TX BY THIS AFTERNOON AND EVENTUALLY
THROUGH THE LOWER RIO GRANDE VALLEY BY TUESDAY MORNING.

...S FL...

A QUASI-LINEAR MCS OR W-E ORIENTED BAND OF TSTMS IS EXPECTED TO BE
ONGOING AT 12Z OVER PARTS OF THE CNTRL INTO SRN PENINSULA. FORCING
ASSOCIATED WITH THE MIDLEVEL TROUGH MOVING THROUGH THE REGION
COUPLED WITH A MOIST AND MODERATELY UNSTABLE AIR MASS /I.E. MLCAPE
OF 1000-2000 J PER KG/ SHOULD SERVE TO SUSTAIN TSTMS SWD THROUGH THE
REMAINDER OF THE PENINSULA TODAY. WHILE A TORNADO OR TWO IS
POSSIBLE WITH ANY EMBEDDED SUPERCELLS...THE GREATER SEVERE THREAT
APPEARS TO BE DAMAGING OUTFLOW WINDS.

...PARTS OF CNTRL/SERN TX...

THE 26/00Z BRO SOUNDING AND CURRENT SATELLITE-DERIVED PW IMAGERY
INDICATE MODEST BOUNDARY LAYER MOISTURE OVER DEEP S TX WHICH WILL BE
DRAWN NWD TODAY WITHIN AN INCREASING SLY FLOW REGIME. THIS MOISTURE
INCREASE COUPLED WITH STEEP LAPSE RATES ARE EXPECTED TO CONTRIBUTE
TO A MODERATELY UNSTABLE...PRE-FRONTAL AIR MASS BY AFTERNOON WHERE
MLCAPE WILL APPROACH 500-800 J/KG.

DUE TO CAPPING ASSOCIATED WITH THE EML...THERE IS SOME QUESTION AS
TO WHETHER STORMS WILL FORM DURING THE DAYLIGHT HOURS. HOWEVER...IT
DOES APPEAR THAT THE GLANCING INFLUENCE OF THE AMPLIFYING MIDLEVEL
WAVE OVER THE MID MS VALLEY ALONG WITH SUSTAINED FRONTAL CONVERGENCE
MAY YIELD ISOLATED TO WIDELY SCATTERED STORMS BY LATE AFTERNOON OR
EARLY EVENING. WHILE THE LOW-LEVEL WIND FIELD IS EXPECTED TO REMAIN
RATHER WEAK...FORECAST HODOGRAPHS EXHIBIT VEERING WINDS WITH HEIGHT
AND 40-45 KT OF DEEP-LAYER SHEAR. GIVEN THE FAVORABLY STEEP LAPSE
RATES...SETUP MAY YIELD A FEW BRIEFLY SEVERE STORMS CAPABLE OF SOME
HAIL AND STRONG WIND GUSTS.

..MEAD/GARNER.. 04/26/2010

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