SPC AC 070559
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1259 AM CDT TUE SEP 07 2010
VALID 081200Z - 091200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
THE LARGE SCALE UPPER FLOW PATTERN WILL AMPLIFY INTO WEDNESDAY. A
CLOSED UPPER LOW WILL MIGRATE EASTWARD OVER SOUTHERN QUEBEC...WITH
SHORTWAVE RIDGING OCCURRING OVER THE NORTHERN PLAINS/UPPER MIDWEST
DOWNSTREAM OF AN AMPLIFYING UPPER TROUGH OVER THE WESTERN STATES.
THE REMNANTS OF TROPICAL SYSTEM HERMINE WILL LIKELY CONTINUE TO MOVE
GENERALLY NORTHWARD ACROSS TX/OK.
...TX/OK...
CURRENT THINKING IS THAT THE REMNANTS OF TROPICAL STORM HERMINE WILL
CONTINUE TO MOVE NORTHWARD/GRADUALLY WEAKEN ACROSS NORTH TX INTO
OK...REFERENCE NHC FORECASTS/DISCUSSIONS FOR THE LATEST DETAILS.
BASED ON THE CURRENT NHC FORECAST AND 00Z BASED NUMERICAL
GUIDANCE...IT APPEARS THAT A RESIDUALLY STRONG RIGHT-PERIPHERAL WIND
ENVELOPE /WITH 1 KM FLOW OF 40 KT OR GREATER/ WILL ACCOMPANY HERMINE
INTO WEDNESDAY. WHILE THE DEGREE OF DAYTIME DESTABILIZATION IS
QUESTIONABLE...EVEN MODEST POCKETS OF HEATING WEDNESDAY AFTERNOON
WOULD ACCOUNT FOR AN ISOLATED/BRIEF TORNADO RISK /AND PERHAPS
DAMAGING WINDS/...GIVEN EXPECTATIONS FOR AMPLE LOW LEVEL SHEAR/SRH.
PENDING THE EVOLUTION OF HERMINE AND A GREATER CONFIDENCE IN
SUFFICIENT DAYTIME DESTABILIZATION ON WEDNESDAY...A SLIGHT RISK MAY
BE NEEDED IN SUBSEQUENT OUTLOOKS FOR PORTIONS OF NORTH TX INTO OK.
...EASTERN GREAT BASIN/CENTRAL ROCKIES...
AS THE WESTERN STATES UPPER TROUGH BEGINS TO SHIFT EASTWARD ON
WEDNESDAY...THE LEADING EDGE OF HEIGHT FALLS/FORCING ALOFT
COINCIDENT WITH A SUFFICIENT PWAT ENVIRONMENT WILL LIKELY YIELD
ISOLATED TO SCATTERED TSTMS...ESPECIALLY WEDNESDAY
AFTERNOON/EVENING. WHILE TOTAL BUOYANCY WILL BE
LIMITED...STRENGTHENING FLOW ALOFT MAY SUPPORT SOME SUSTAINED
STRONG/PERHAPS SEVERE TSTMS CAPABLE OF HAIL/GUSTY WINDS.
...NORTH-CENTRAL HIGH PLAINS...
AHEAD OF THE CONSIDERABLE WESTERN STATES UPPER TROUGH...WARM
FRONT/ATTENDANT MOIST AIR MASS WILL RETREAT NORTHWARD ACROSS THE
CENTRAL HIGH PLAINS ON WEDNESDAY. 00Z BASED NUMERICAL GUIDANCE IS
SUGGESTIVE OF THE POSSIBILITY OF A LEAD SHORTWAVE TROUGH CROSSING
THE REGION RELATIVELY EARLY IN THE DAY...AS THE LEADING EDGE OF
LARGE SCALE HEIGHT FALLS OTHERWISE OVERSPREAD THE REGION. CURRENT
THINKING IS THAT TSTMS WILL DEVELOP/INCREASE ACROSS THE CENTRAL HIGH
PLAINS DURING THE AFTERNOON/EVENING IN VICINITY OF A SURFACE LOW AND
LEE TROUGH. WHILE AT LEAST ISOLATED SEVERE TSTMS WILL BE
POSSIBLE...UNCERTAINTY REMAINS REGARDING 1/ THE OVERALL DEGREE OF
DESTABILIZATION...AS WELL AS 2/ TIMING OF THE AFOREMENTIONED
SHORTWAVE TROUGH AND THE POSSIBILITY OF LIMITED FORCING ACROSS MUCH
OF THE WARM SECTOR DURING PEAK HEATING. NONETHELESS...THE REGION
WILL BE MONITORED FOR AN UPGRADE TO SLIGHT RISK IN SUBSEQUENT
OUTLOOKS.
OTHERWISE...WITH AN INCREASINGLY STRONG LOW LEVEL JET/ELEVATED
MOISTURE TRANSPORT REGIME NORTH OF THE CONTINUALLY RETREATING WARM
FRONT...TSTMS SHOULD ESPECIALLY INCREASE LATE WEDNESDAY EVENING AND
OVERNIGHT ACROSS MUCH OF THE NORTHERN PLAINS TO THE ADJACENT UPPER
MIDWEST. THE STRONGEST STORMS WEDNESDAY NIGHT MAY BE CAPABLE OF
SEVERE HAIL/PERHAPS GUSTY WINDS.
...MAINE/COASTAL NEW ENGLAND...
CLOSED UPPER LOW IS EXPECTED TO TRANSITION GENERALLY EASTWARD OVER
SOUTHERN QUEBEC ON WEDNESDAY WITH STRONG CYCLONIC FLOW ALOFT
OVERSPREADING THE NORTHEAST STATES. THE TIMING OF THE ASSOCIATED
COLD FRONT IS STILL QUESTIONABLE...AS TO WHETHER SUFFICIENT
DESTABILIZATION MAY OCCUR FOR A SEVERE THREAT PRIOR TO THE COLD
FRONT MOVING OFFSHORE. IF A SOMEWHAT SLOWER COLD FRONTAL MOVEMENT
MATERIALIZES...A DAMAGING WIND THREAT COULD EXIST...AND SUCH WILL BE
REEVALUATED IN SUBSEQUENT OUTLOOKS.
..GUYER.. 09/07/2010
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
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