DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 161556
SWODY1
SPC AC 161555

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1055 AM CDT FRI APR 16 2010

VALID 161630Z - 171200Z

...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON/EVENING FROM SRN
INDIANA TO PA...

...SYNOPSIS...
WEAK SPLIT FLOW REGIME WILL CONTINUE THROUGH TOMORROW AS A SRN
STREAM TROUGH MOVES ESEWD FROM SRN CA TO NRN MEXICO...AND A WEAK
DOWNSTREAM LOW DRIFTS EWD OVER NW TX. MEANWHILE...A STRONGER NRN
STREAM TROUGH WILL DIG SEWD OVER THE GREAT LAKES TO OH/PA/NY BY
TONIGHT. THIS SYSTEM WILL BE ACCOMPANIED BY A SURFACE COLD FRONT
WHICH WILL FOCUS THE THREAT FOR STRONG/SEVERE THUNDERSTORMS THIS
AFTERNOON/EVENING.

...SRN INDIANA ENEWD TO PA THIS AFTERNOON/EVENING...
IN ADVANCE OF THE AMPLIFYING MID LEVEL TROUGH...A SURFACE COLD FRONT
WILL MOVE SEWD ACROSS THE OH VALLEY REGION. REGIONAL 12Z SOUNDINGS
AND SURFACE ANALYSES REVEAL A NARROW CORRIDOR OF LOW-LEVEL MOISTURE
/BOUNDARY LAYER DEWPOINTS IN THE MID 50S/ SPREADING ENEWD AHEAD OF
THE FRONT. LOW-LEVEL LAPSE RATES WILL ALSO BECOME QUITE STEEP THIS
AFTERNOON AS SURFACE TEMPERATURES APPROACH 80 F. THE NET RESULT
WILL BE A NARROW PRE-FRONTAL CORRIDOR OF WEAK INSTABILITY AND
INVERTED-V PROFILES THIS AFTERNOON ACROSS THE SLIGHT RISK AREA.

SCATTERED THUNDERSTORMS SHOULD DEVELOP BY EARLY AFTERNOON
ALONG/AHEAD OF THE FRONT AND THICKER CLOUD BAND FROM W/NW PA INTO
CENTRAL OH. STORMS WILL THEN SPREAD EWD INTO PA AND DEVELOP WSWWD
IN A BROKEN BAND TO SRN INDIANA. THESE STORMS WILL BE CAPABLE OF
PRODUCING DAMAGING WINDS AS A RESULT OF INCREASING MIDLEVEL FLOW
/NEAR 50 KT AT 700 MB/ AND ASSOCIATED MOMENTUM TRANSFER POTENTIAL IN
THE ENVIRONMENT WITH STEEP LOW-LEVEL LAPSE RATES. THE SEVERE STORM
THREAT WILL DECREASE RAPIDLY BY LATE EVENING AS THE BOUNDARY LAYER
STABILIZES AND INSTABILITY DIMINISHES.

..THOMPSON/ROGERS.. 04/16/2010

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