Saturday, May 23, 2009

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 230555
SWODY2
SPC AC 230553

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1253 AM CDT SAT MAY 23 2009

VALID 241200Z - 251200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
VERY WEAK MID-LEVEL PATTERN IS FORECAST TO CONTINUE ACROSS MOST OF
THE CONUS ATTM...WITH THE EXCEPTION OF NEW ENGLAND WHICH WILL REMAIN
NEAR THE SRN FRINGE OF A STRONG ERN CANADA TROUGH.

A SMALL UPPER LOW WILL CONTINUE DRIFTING NNWWD ACROSS THE S CENTRAL
CONUS...WHILE A PAIR OF WEAK TROUGHS WILL SHIFT EWD ACROSS THE
ROCKIES...WITH THE INITIAL FEATURE PROGGED TO AFFECT THE HIGH PLAINS
-- PARTICULARLY DURING THE SECOND HALF OF THE PERIOD.

AT THE SURFACE...A COLD FRONT WILL CONTINUE CROSSING NEW
ENGLAND...WHILE THE TRAILING PORTION OF THE BOUNDARY LINGERS WWD
ACROSS THE MIDWEST/OH VALLEY REGION.

ELSEWHERE...A WEAK LOW/LEE TROUGH IS FORECAST ACROSS THE HIGH
PLAINS...WHILE A SECOND/WEAK LOW DRIFTS ACROSS THE AR/LA REGION
THROUGH THE PERIOD.

...NRN HIGH PLAINS...
LEE TROUGHING/WEAK CYCLOGENESIS IS FORECAST OVER THE NRN HIGH
PLAINS...AS A WEAK MID-LEVEL TROUGH SHIFTS EWD ACROSS THE CENTRAL
AND NRN ROCKIES. MODEST LOW-LEVEL MOISTURE/MID-LEVEL LAPSE RATES
WILL SUPPORT LIMITED DESTABILIZATION -- BUT THIS SHOULD BE
SUFFICIENT FOR THE DEVELOPMENT OF ISOLATED AFTERNOON STORMS -- BOTH
INVOF THE LEE TROUGH AND EWD INTO SD ALONG A WEAK WARM FRONT.

WHILE DEEP-LAYER WIND FIELD WILL REMAIN GENERALLY WEAK...LOW-LEVEL
SELYS VEERING TO MODEST WSWLY FLOW WITH HEIGHT WILL RESULT IN SHEAR
SUFFICIENT FOR A FEW ORGANIZED/ROTATING STORMS. THOUGH IT APPEARS
AT THIS POINT THAT STORM COVERAGE -- AND THUS SEVERE THREAT -- WILL
REMAIN LIMITED...WILL INTRODUCE 5% SEVERE PROBABILITY ATTM.

...SRN NEW ENGLAND/MID-ATLANTIC REGION...
WEAK DESTABILIZATION IS FORECAST ACROSS SRN NEW ENGLAND AND INTO
SERN NY/ERN PA/NJ/THE DELMARVA REGION...AHEAD OF THE WEAK/ADVANCING
COLD FRONT. DESTABILIZATION SHOULD BE SUFFICIENT TO SUPPORT
DEVELOPMENT OF SHOWERS AND ISOLATED THUNDERSTORMS DURING THE
AFTERNOON.

WHILE CONVECTION WILL ALSO DEVELOP WWD ACROSS THE OH VALLEY ALONG
TRAILING PORTIONS OF THE FRONT...VERY WEAK FLOW SUGGESTS NO MORE
THAN ISOLATED/PULSE-TYPE SEVERE POTENTIAL.
HOWEVER...SLIGHTLY-STRONGER FLOW ALOFT ALONG SRN FRINGES OF THE ERN
CANADA/NERN U.S. TROUGH MAY SUPPORT SOMEWHAT-MORE
ORGANIZED/LONG-LIVED STORMS OVER SRN NEW ENGLAND/THE MID-ATLANTIC
REGION. THUS...WILL INCLUDE LOW-PROBABILITY SEVERE POTENTIAL THIS
FORECAST...TO HIGHLIGHT THE LOW-END THREAT FOR HAIL/WIND WHICH MAY
LINGER INTO THE EARLY EVENING HOURS.

..GOSS.. 05/23/2009

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