DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 112000
SWODY1
SPC AC 111957

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0257 PM CDT FRI SEP 11 2009

VALID 112000Z - 121200Z

...NO SVR TSTM AREAS FORECAST...

...CENTRAL PLAINS...
GENERALLY DIURNALLY-DRIVEN TSTMS WILL CONTINUE TO DEVELOP ALONG
FRONTAL ZONE PROGRESSING SWD THROUGH THE CENTRAL PLAINS...AND MORE
SLOWLY EWD THROUGH MN...AS THE BOUNDARY CONTINUES TO ENCOUNTER A
MODERATELY UNSTABLE AIR MASS /MLCAPE AOA 1000 J/KG/. THE COLD FRONT
WILL CONTINUE TO MOVE AWAY FROM STRONGER DEEP LAYER SHEAR PRECLUDING
THE LIKELIHOOD FOR AN ORGANIZED SEVERE THREAT WITH EXPECTED TSTM
ACTIVITY. HOWEVER...A PLUME OF STEEP MID LEVEL LAPSE RATES
EXTENDING FROM SERN CO TO NWRN IA SUGGEST A FEW STRONGER STORMS WILL
BE CAPABLE OF PRODUCING MARGINALLY SEVERE HAIL ALONG WITH GUSTY
WINDS.

..PETERS/COOK.. 09/11/2009

.PREV DISCUSSION... /ISSUED 1052 AM CDT FRI SEP 11 2009/

AS STRONG UPPER HIGH ROTATES NWD INTO SRN ALBERTA...A RATHER
VIGOROUS UPPER LOW WILL CONTINUE DROPPING SWD THRU THE WRN DAKOTAS
THIS FORECAST PERIOD. COLD FRONT AHEAD OF UPPER LOW IS SURGING SWD
THRU THE CENTRAL HIGH PLAINS THIS MORNING SOMEWHAT AHEAD OF EARLIER
MODEL RUNS. BY LATER THIS AFTERNOON FRONT WILL EXTEND FROM CENTRAL
NEB TO SWRN KS THEN ACROSS NRN TX PANHANDLE INTO NERN NM.

THE VERY MOIST AIR MASS ACROSS TX INTO OK WILL CONTINUE TO SPREAD
SLOWLY W AND N AND WITH THE FRONTAL CONVERGENCE LEAD TO THUNDERSTORM
DEVELOPMENT BY LATER THIS AFTERNOON/EVENING. WHILE MLCAPES IN
ADVANCE OF FRONT WILL CLIMB TO AOA 1000 J/KG...MORE THAN SUFFICIENT
FOR CONVECTION...THE GENERALLY VERY WEAK SHEAR PRECLUDES AN
ORGANIZED SEVERE THREAT. THERE WILL LIKELY BE A FEW STRONGER STORMS
BY MAX HEATING CAPABLE OF MARGINALLY SEVERE HAIL GIVEN THE MID LEVEL
LAPSE RATES IN EXCESS OF 8C/KM NOTED ON BOTH LBF AND DNR 12Z
SOUNDINGS...ALONG WITH GUSTY WINDS. HOWEVER WITH FRONT SO FAR IN
ADVANCE OF UPPER LOW...THE SURFACE TO 6 KM SHEAR WILL BE GENERALLY
LESS THAN 20KT AND AN ORGANIZED STORMS/SEVERE THREAT IS NEGLIGIBLE.

HAVE DROPPED THE THREAT OF SEVERE ALONG THE NJ COAST...AS
INSTABILITY IS LACKING IN THE STRONG ONSHORE FLOW AHEAD OF THE
SURFACE LOW MOVING SLOWLY NWD IN THIS AREA.

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