Sunday, June 14, 2009

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 141737
SWODY2
SPC AC 141734

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1234 PM CDT SUN JUN 14 2009

VALID 151200Z - 161200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE PLAINS STATES SEWD
INTO THE MID MS/LOWER OH/TN VALLEYS AND THE SOUTHEAST...

...SYNOPSIS...
WHILE TROUGHS PERSIST OVER BOTH THE WRN AND ERN CONUS...SEVERAL
VORTICITY MAXIMA WILL CONTINUE SHIFTING ACROSS THE PLAINS IN AN
ANTICYLONIC ARC ATOP THE S CENTRAL U.S. RIDGE.

AT THE SURFACE...A FRONT WILL PERSIST FROM THE SOUTHEAST WNWWD INTO
THE PLAINS -- WHERE ONE OR MORE W-E WARM FRONTAL SEGMENTS ARE
ANTICIPATED. MEANWHILE...A LEE TROUGH IS FORECAST OVER THE HIGH
PLAINS...IN RESPONSE TO PERSISTENT WSWLY FLOW ACROSS THE ROCKIES.

...THE CENTRAL PLAINS AND VICINITY...
STORMS SHOULD BE ONGOING ACROSS PARTS OF THE PLAINS -- PARTICULARLY
OVER NEB/ERN KS -- AT THE START OF THE PERIOD...WITH MODERATE
DESTABILIZATION EXPECTED OVER THE PLAINS IN THE WAKE OF THIS
CONVECTION.

STORM REDEVELOPMENT IS FORECAST DURING THE AFTERNOON...ALONG AND
NEAR ONE OR MORE W-E SURFACE BOUNDARIES EXTENDING EWD FROM WEAK LOW
CENTERS ALONG A LEE TROUGH OVER THE HIGH PLAINS. GIVEN MODERATE WLY
MID-LEVEL FLOW...STORMS WILL BECOME SEVERE/SUPERCELLULAR...CAPABLE
OF PRODUCING LARGE HAIL AND DAMAGING WINDS ALONG WITH THE POTENTIAL
FOR ISOLATED TORNADOES. A FEW ISOLATED CELLS MAY DEVELOP AS FAR S
AS WRN OK AND INTO PARTS OF WRN TX...WHERE A MORE DEEPLY-MIXED
BOUNDARY LAYER IS EXPECTED.

OVERNIGHT...STORMS SHOULD PERSIST...DEVELOPING INTO ONE OR MORE
CLUSTERS AND THEN SPREADING SEWD ACROSS THE PLAINS ALONG WITH
ATTENDANT DAMAGING WIND/HAIL THREAT.

...LOWER MO/MID MS/LOWER OH/TN VALLEYS AND INTO GA...
STORMS -- LIKELY IN THE FORM OF ONE OR MORE ORGANIZED/SEWD-MOVING
CLUSTERS -- SHOULD BE ONGOING AT THE START OF THE PERIOD WITHIN A
ZONE FROM NEB/ERN KS SEWD ACROSS MO AND INTO THE MID MS/TN
VALLEYS...AS WARM ADVECTION ASSOCIATED WITH A VEERING LOW-LEVEL JET
OVER THE ERN PLAINS COMBINES WITH SEVERAL SHORT-WAVE FEATURES
TOPPING THE SRN PLAINS RIDGE. WHILE AN ONGOING SEVERE THREAT --
MAINLY IN THE FORM OF DAMAGING WINDS -- IS EXPECTED WITH THE
CONVECTION AS IT SPREADS SEWD TOWARD THE SOUTHEAST U.S. WITH TIME.

LATER AFTERNOON REDEVELOPMENT OF CONVECTION IS MORE DIFFICULT TO
DISCERN...GIVEN EFFECTS OF PERSISTENT PRECIPITATION/CLOUDINESS AND
THEIR EFFECTS ON AFTERNOON DESTABILIZATION. FROM A BROADER
PERSPECTIVE HOWEVER...MODERATE WLY/WNWLY FLOW ALOFT ACROSS THIS
REGION ATOP A SURFACE FRONT LYING WNW-ESE ACROSS THE AREA SHOULD
SUPPORT ADDITIONAL DEVELOPMENT OF STORMS ACROSS THIS REGION DURING
THE AFTERNOON. WITH AT LEAST POCKETS OF MODERATE DESTABILIZATION
EXPECTED...AND SHEAR SUPPORTIVE OF ORGANIZED/SUPERCELL
STORMS...EXPECT LARGE HAIL AND DAMAGING WIND THREAT TO INCREASE
THROUGH THE AFTERNOON...ALONG WITH THE POTENTIAL FOR ISOLATED
TORNADOES. STORMS MAY EVENTUALLY ORGANIZE INTO ONE OR MORE CLUSTERS
OVERNIGHT -- PARTICULARLY ACROSS MO WHERE A SWLY LOW-LEVEL JET
SHOULD REDEVELOP. ANY CONVECTION WHICH CONTINUES THROUGH THE
EVENING/OVERNIGHT WOULD LIKELY RESULT IN CONTINUED SEVERE POTENTIAL.

...THE CAROLINAS...
UPPER DISTURBANCES MOVING SEWD ACROSS THE CAROLINAS AND VICINITY
WITHIN DIFFLUENT/NWLY FLOW ALOFT SHOULD COMBINE WITH AFTERNOON
DESTABILIZATION TO SUPPORT THE DEVELOPMENT OF SHOWERS AND
THUNDERSTORMS ACROSS THIS REGION -- WITH SOME ADDITIONAL POTENTIAL
FOR REMNANT STORM CLUSTERS TO SPREAD ACROSS THIS REGION FROM THE
WEST.

FLOW ALOFT SHOULD REMAIN RELATIVELY MODEST ACROSS THIS REGION...BUT
SUFFICIENT FOR LOCALLY ORGANIZED/MULTICELL STORMS. STRONGEST
STORMS/STORM CLUSTERS WILL BE CAPABLE OF MARGINAL HAIL AND
LOCALLY-GUSTY WINDS THROUGH EARLY EVENING.

...NY/ERN PA...
MODEST DESTABILIZATION IS FORECAST ACROSS PARTS OF NY/PA...DRIVEN BY
DAYTIME HEATING BENEATH A MID-LEVEL CIRCULATION CENTER CROSSING THIS
AREA. SHOWERS AND SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP
DURING THE AFTERNOON...THE STRONGEST OF WHICH COULD PRODUCE MARGINAL
HAIL OR LOCALLY-GUSTY WINDS BEFORE DIMINISHING AFTER SUNSET.

..GOSS.. 06/14/2009

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