Tuesday, February 28, 2012

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 281730
SWODY2
SPC AC 281729

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1129 AM CST TUE FEB 28 2012

VALID 291200Z - 011200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MID/LOWER MS VALLEY
EWD TO THE MID-ATLANTIC/CAROLINA COAST...

...SYNOPSIS...
A WEAKENING UPPER LOW INITIALLY CROSSING THE MID MO/UPPER MS VALLEYS
IS EXPECTED TO CONTINUE MOVING EWD ACROSS THE UPPER GREAT LAKES
REGION THROUGH THE PERIOD...AS A SECOND/LARGE TROUGH EXPANDS OVER
THE WRN CONUS. ON THE SRN FRINGE OF THESE TWO FEATURES...VERY FAST
WLY/WSWLY FLOW ALOFT IS PROGGED FROM THE SOUTHWEST/SRN ROCKIES
ACROSS MUCH OF THE CENTRAL AND ERN CONUS.

AT THE SURFACE...A DEEP/OCCLUDED LOW IS INITIALLY PROGGED OVER THE
SRN MN VICINITY...WITH A COLD FRONT EXTENDING FROM A CENTRAL IL
TRIPLE POINT SWWD INTO TX...AND A WARM FRONT DRAPED EWD ACROSS THE
OH VALLEY. THE LOW IS FORECAST TO WEAKEN THROUGH THE PERIOD AS IT
SHIFTS EWD ACROSS THE UPPER GREAT LAKES...WITH THE TRAILING COLD
FRONT LIKEWISE PROGGED TO WEAKEN AS IT CROSSES THE OH/TN VALLEYS
THROUGH THE DAY...AND THEN CROSSES THE APPALACHIANS THROUGH THE END
OF THE PERIOD. WHILE WEAKENING OVERALL...THIS STORM SYSTEM SHOULD
SUPPORT WIDESPREAD CONVECTION AND A FAIRLY LARGE SEVERE THREAT AREA.

...MID/LOWER MS VALLEY EWD TO THE MID-ATLANTIC COAST...
WIDESPREAD SHOWERS AND THUNDERSTORMS SHOULD BE ONGOING INVOF THE
ADVANCING COLD FRONT AT THE START OF THE PERIOD...AND EWD ACROSS THE
OH/TN VALLEYS IN THE ZONE OF WARM ADVECTION AHEAD OF THE SYSTEM.
THE ONGOING PRECIPITATION/CLOUD COVER ACROSS THE BULK OF THE
FORECAST SEVERE RISK AREA WILL ACT TO HINDER HEATING/DESTABILIZATION
DURING THE DAY...BUT EXPECT AMPLE CAPE -- AIDED BY NWD ADVECTION OF
HIGHER THETA-E AIR -- TO SUPPORT ONGOING STORMS.

THOUGH INSTABILITY SHOULD REMAIN LIMITED IN MOST AREAS...VERY STRONG
KINEMATIC ENVIRONMENT WILL EXIST...WITH VERY
STRONG/QUASI-UNIDIRECTIONAL WSWLY FLOW EXPECTED THROUGHOUT THE
CLOUD-BEARING LAYER. WHILE LIMITED POTENTIAL FOR HAIL AND A COUPLE
OF ISOLATED TORNADOES APPEARS POSSIBLE...MAIN SEVERE THREAT THIS
PERIOD WILL LIKELY BE DAMAGING WINDS -- WITH FAST-MOVING LINES/LINE
SEGMENTS. THE GREATEST THREAT SHOULD OCCUR THROUGH THE AFTERNOON
ALONG AND WEST OF THE APPALACHIANS -- INCLUDING THE MID AND UPPER OH
AND TN VALLEYS. SOME THREAT MAY CROSS THE APPALACHIANS OVERNIGHT AS
THE WEAKENING FRONT ADVANCES...WITH THREAT POSSIBLY REACHING THE
MID-ATLANTIC/CAROLINA COAST THROUGH THE END OF THE PERIOD.

..GOSS.. 02/28/2012

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