Tuesday, April 17, 2012

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 170542
SWODY2
SPC AC 170541

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1241 AM CDT TUE APR 17 2012

VALID 181200Z - 191200Z

...NO SVR TSTM AREAS FORECAST...

...SERN U.S...

SRN STREAM SHORT-WAVE TROUGH IS EXPECTED TO DEAMPLIFY AS IT
PROGRESSES ACROSS THE GULF STATES TOWARD THE CAROLINA COAST LATE IN
THE PERIOD. WHILE THIS FEATURE IS NOT PARTICULARLY STRONG IT
APPEARS LARGE SCALE ASCENT DOWNSTREAM ACROSS PORTIONS OF NRN FL/GA
INTO THE CAROLINAS WILL CONTRIBUTE TO SCATTERED THUNDERSTORM
DEVELOPMENT BY MID DAY AS BOUNDARY LAYER WARMS/DESTABILIZES.
STEEPEST LOW LEVEL LAPSE RATES WILL BE NOTED ACROSS THE NRN FL
PENINSULA ARCING ACROSS SERN GA INTO SC...ROUGHLY WITHIN 100 MI OF
THE ATLANTIC COAST AND THIS BODES WELL FOR ROBUST UPDRAFTS.
FORECAST SOUNDINGS SUGGEST CONVECTIVE TEMPERATURES IN THE MID-UPPER
70S WILL BE REACHED BY 18Z AND DEEP LAYER SHEAR ON THE ORDER OF
25-30KT WOULD SEEM SUPPORTIVE OF MULTI-CELL UPDRAFTS AND PERHAPS
EVEN A FEW WEAK SUPERCELLS. WILL INTRODUCE 5% PROBS TO ACCOUNT FOR
A FEW MARGINALLY SEVERE THUNDERSTORMS PRIMARILY DURING THE AFTERNOON
HOURS.

...MID MS VALLEY...

SHORT-WAVE TROUGH WILL EJECT ACROSS THE UPPER MS VALLEY INTO THE
GREAT LAKES DURING THE FIRST HALF OF THE PERIOD WHICH WILL FORCE A
COLD FRONT TO A POSITION FROM LAKE MI...SWWD ACROSS SRN IA INTO SERN
NEB BY 19/00Z. LATEST DATA SUGGESTS A NARROW AXIS OF LOW LEVEL
MOISTURE WITH SFC DEW POINTS INTO THE LOWER 50S WILL ADVECT AHEAD OF
THE BOUNDARY ACROSS ERN IA INTO SWRN WI. IF TEMPERATURES CAN WARM
INTO THE MID 60S OVER THIS REGION IT APPEARS FRONTAL CONVERGENCE
WILL PROVE ADEQUATE IN GENERATING CONVECTION. ALTHOUGH INSTABILITY
IS NOT EXPECTED TO BE THAT SIGNIFICANT IT APPEARS A FEW
STRONG...PERHAPS EVEN ISOLATED SEVERE THUNDERSTORMS WILL FORM BY
21-22Z. CONVECTION MAY DEVELOP SWWD ALONG THE TRAILING BOUNDARY
TOWARD 00Z ACROSS SRN IA/NRN MO WHERE LESS FORCING WILL BE NOTED BUT
STRONGER HEATING WILL RESULT IN GREATER INSTABILITY. WITH LLJ
EXPECTED TO IMPINGE ON THE TRAILING FRONT DURING THE OVERNIGHT HOURS
CONSIDERABLY MORE CONVECTION MAY EVOLVE WITHIN THE WARM ADVECTION
ZONE FROM SERN NEB INTO SWRN IA WELL AFTER DARK. FORECAST SOUNDINGS
SUGGEST HAIL COULD ACCOMPANY THIS ELEVATED ACTIVITY THAT FORMS
ALONG/NORTH OF THE BOUNDARY. AT THIS TIME WILL NOT INTRODUCE A
SLIGHT RISK BUT MUCAPE ON THE ORDER OF 1000 J/KG MAY WARRANT
INCREASED SEVERE PROBS FOR LATE NIGHT STORMS. WILL MONITOR THIS
REGION FOR POSSIBLE UPGRADE IN LATER OUTLOOKS.

..DARROW.. 04/17/2012

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