[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 200538
SWODY1
SPC AC 200537

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1237 AM CDT WED SEP 20 2006

VALID 201200Z - 211200Z

...NO SVR TSTM AREAS FORECAST...

...NEB/KS/OK AND TX PANHANDLES...
A PROGRESSIVE UPPER-LEVEL TROUGH EVIDENT ON WATER VAPOR IMAGERY OVER
THE WRN U.S. WILL MOVE EWD AND CLOSE-OFF CROSSING THE ROCKIES TODAY.
MOISTURE WILL RETURN NWD INTO THE HIGH PLAINS AHEAD OF THE
APPROACHING SYSTEM BUT A CAPPING INVERSION SHOULD REMAIN IN PLACE
ACROSS MOST OF THE REGION THROUGH THE AFTERNOON. THE EXCEPTION MAY
BE OVER WEST TX WHERE A FEW STORMS MAY INITIATE DURING THE LATE
AFTERNOON WHERE INSTABILITY AND SHEAR IS FORECAST TO BE SLIGHTLY
GREATER. HOWEVER...MOST OF THE CONVECTIVE DEVELOPMENT SHOULD HOLD
OFF UNTIL LARGE-SCALE ASCENT RAPIDLY INCREASES WHEN THE UPPER-LOW
DRIFTS EWD AND BEGINS TO AFFECT THE HIGH PLAINS AND WEST TX IN THE
04Z TO 08Z TIMEFRAME. ALTHOUGH FORECAST SOUNDINGS SHOW STRONG ENOUGH
VERTICAL SHEAR TONIGHT FOR ISOLATED SUPERCELLS...MOISTURE WILL NOT
HAVE VERY LONG TO RETURN AHEAD OF THE APPROACHING SYSTEM. AS A
RESULT...INSTABILITY SHOULD REMAIN RELATIVELY WEAK AS THE SYSTEM
EJECTS INTO THE PLAINS TONIGHT. STEEP MID-LEVEL LAPSE RATES WILL
EXIST AND ELEVATED INSTABILITY WILL BE PRESENT WHICH CONSIDERING THE
STRONG ASCENT SHOULD BE FAVORABLE FOR MARGINALLY SEVERE HAIL STORMS.
IF IT APPEARS LIKELY THAT INSTABILITY WILL BE GREAT ENOUGH FOR THE
FORMATION OF SUPERCELLS OVER A LARGER AREA...AN UPGRADE TO SLIGHT
RISK MAY BECOME NECESSARY IN LATER OUTLOOKS.

...SRN AND CNTRL FL...
A COLD FRONT OVER THE CNTRL FL PENINSULA THIS MORNING WILL MOVE
SLOWLY SWD TODAY. A LINEAR MCS SHOULD BE ONGOING THIS MORNING ALONG
THE BOUNDARY WITH THE LINE OF THUNDERSTORMS MOVING INTO SRN FL THIS
AFTERNOON. FORECAST SOUNDINGS EARLY THIS AFTERNOON IN CNTRL AND SRN
FL SHOW STEEP LOW-LEVEL LAPSE RATES AND RELATIVELY STRONG LOW-LEVEL
WLY UNIDIRECTIONAL FLOW. THIS MAY BE ENOUGH FOR A FEW MARGINALLY
SEVERE WIND GUSTS WITH THE STRONGER LINE SEGMENTS NEAR PEAK HEATING
THIS AFTERNOON.

..BROYLES/GRAMS.. 09/20/2006