SPC AC 081251
STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK
DAY 1 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWE46 KWNS.
VALID 081300Z - 091200Z

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 15
NNE FSI 40 SW P28 10 SSE RSL 30 W BIE 60 NNE OMA 35 SSE MCW 35 WNW
MLI 30 WNW CGI 40 SW GLH 45 S SHV 35 S DAL 15 NNE FSI.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 20 SSE DTW 25 NNW
SDF 45 NE CBM 20 ENE MCB 10 WSW LFT 45 WNW BPT 40 S SEP 25 SW FSI
25 NNW GAG 25 SSE EHA 40 W CVS 25 W ONM 40 NE INW 30 NW U17 50 NNW
CAG 30 WSW SNY 35 S MCK 20 E GRI 10 S FRM 30 NNW AUW 45 E MQT.
POWERFUL...SPRINGLIKE SYSTEM IS FORECAST TO CONTINUE ACROSS THE
ROCKIES AND INTO THE PLAINS THIS FORECAST PERIOD. EARLY MORNING
WATER VAPOR IMAGERY SHOWS THE MAIN FEATURE APPROACHING THE GREAT
BASIN REGION...AND A SECONDARY SHORTWAVE TROUGH MOVING INTO WESTERN
NEW MEXICO. THESE TWO FEATURES ARE EXPECTED TO MERGE LATER THIS
MORNING/AFTERNOON AS THEY EMERGE INTO THE PLAINS. AT THE
SURFACE...A COMPLEX PATTERN HAS EVOLVED ACROSS THE CENTRAL ROCKIES
INTO THE PLAINS REGION. SHALLOW COLD AIR MASS HAS SURGED SOUTHWARD
INTO SOUTHERN KANSAS...BUT SHOULD RETREAT SLIGHTLY NORTHWARD AHEAD
OF THE APPROACHING TROUGH.

...MID MISSISSIPPI/LOWER MISSOURI VALLEYS/CENTRAL PLAINS...
THE MAJORITY OF THE ENERGY ASSOCIATED WITH THIS STRONG TROUGH IS
EXPECTED TO MOVE ACROSS THIS REGION LATER THIS AFTERNOON INTO THE
EVENING HOURS. AS THIS HAPPENS...A SURFACE LOW WILL DEVELOP OVER
SOUTHERN KANSAS AND MOVE RAPIDLY NORTHEASTWARD ALONG THE WARM FRONT

...PERHAPS REACHING CENTRAL WISCONSIN BY 12Z SATURDAY. INCREASING
SOUTHEASTERLY LOW LEVEL FLOW IN THE WARM SECTOR WILL HELP TRANSPORT
MOISTURE AHEAD OF THE ADVANCING SYSTEM...AND WITH STRONG MID LEVEL
COOLING...THE AIR MASS SHOULD BECOME MODERATELY UNSTABLE. THE
LATEST ETA GUIDANCE SUGGEST SURFACE BASED LIFTED INDICES COULD BE
IN THE -4 TO -6 RANGE BY LATE AFTERNOON. FORECAST SOUNDINGS SHOW
LOW LEVEL FLOW INCREASING TO MORE THAN 50 KNOTS JUST OFF THE
SURFACE. WITH SOME BACKING POSSIBLE IN THE LOW LEVELS...THE
ENVIRONMENT IN THE WARM SECTOR MAY BECOME INCREASINGLY FAVORABLE
FOR STORM ROTATION.
THUNDERSTORMS SHOULD DEVELOP LATER THIS AFTERNOON AS FORCING IN THE
VICINITY OF THE FRONT AS WELL AS WITH THE UPPER SYSTEM SUFFICIENTLY
WEAKENS THE CAP. ACTIVITY SHOULD BEGIN AS WIDELY SCATTERED TO
SCATTERED CELLS. THE STRENGTH OF THE WINDS AND THE LOW LEVEL
VEERING MAY TEND TO SUPPORT STORM ROTATION WITH THE POTENTIAL FOR
ISOLATED TORNADOES...LARGE HAIL...AND DAMAGING WINDS. AS THE
EVENING PROGRESSES...THE ACTIVITY MAY BECOME MORE WIDESPREAD AND
WILL LIKELY EVOLVE INTO A SQUALL LINE AS IT MOVES RAPIDLY
NORTHEASTWARD. AT THAT TIME...THE GREATEST SEVERE THREAT SHOULD BE
FROM DAMAGING WINDS.

...SOUTHERN PLAINS...
EARLY MORNING SATELLITE IMAGERY SHOWS AN EXTENSIVE CLOUD SHIELD
ACROSS A LARGE PART OF OKLAHOMA AND NORTH TEXAS...AND MORNING
SOUNDINGS FROM NORMAN AND FORT WORTH SHOW THE PRESENCE OF A RATHER
STRONG CAP IN PLACE. THESE TWO FACTORS HAVE CREATED AN UNFAVORABLE
ENVIRONMENT FOR MORE THAN ISOLATED TO WIDELY SCATTERED THUNDER-
STORMS ACROSS PORTIONS OF OKLAHOMA AND TEXAS. WHILE THE MOISTURE
HAS BEEN INCREASING...THE ARCTIC INTRUSIONS OF THE PAST TWO WEEKS
HAVE GREATLY REDUCED THE QUALITY OF THE RETURNING AIR MASS
NECESSARY FOR SEVERE STORMS.
NEVERTHELESS...THE FORCING WITH THE UPPER SYSTEM AND CONVERGENCE
ALONG THE DRYLINE...ALBEIT WEAK...SHOULD AID THUNDERSTORM
DEVELOPMENT DURING THE LATE AFTERNOON AND EARLY EVENING HOURS. THE
ADVANCING COLD FRONT WILL ALSO AID LOW LEVEL FORCING DURING THE
LATER HOURS. WINDS IN THE 925 MB TO 700 MB LAYER ARE EXPECTED TO
INCREASE TO MORE THAN 50 KNOTS WHICH WILL CREATE AN ENVIRONMENT
FAVORABLE FOR DAMAGING GUSTS WITH THE STRONGEST STORMS. IF LOW
LEVEL FLOW AHEAD OF THE COLD FRONT IS ABLE TO BACK...THERE COULD BE
POTENTIAL FOR AN ISOLATED TORNADO OR TWO.

..REHBEIN.. 03/08/02