[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 211223
SWODY1
SPC AC 211222

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0722 AM CDT THU SEP 21 2006

VALID 211300Z - 221200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF
KS...OK...TX...MO...AND AR...

...CENTRAL KS/OK THIS AFTERNOON AND EVENING...
IMPRESSIVE UPPER LOW OVER CO/NM WILL SURGE EASTWARD ACROSS THE
CENTRAL PLAINS TODAY BEFORE WEAKENING AND LIFTING NORTHWARD LATE
TONIGHT.  STRONG FORCING FOR UPWARD VERTICAL MOTION HAS OVERSPREAD
MUCH OF KS/OK AND NORTH TX THIS MORNING...WITH NUMEROUS SHOWERS/
THUNDERSTORMS WITHIN WARM CONVEYOR BELT.  THIS ACTIVITY IS EXPECTED
TO MOVE EASTWARD AND AWAY FROM KS/OK DRYLINE BY EARLY AFTERNOON.  A
COUPLE HOURS OF HEATING ALONG DRYLINE...COUPLED WITH NORTHWARD
TRANSPORT OF MID/UPPER 50S SURFACE DEWPOINTS WILL RESULT IN A NARROW
AXIS OF MODERATE INSTABILITY FROM SOUTH CENTRAL KS INTO CENTRAL OK. 
PRESENT INDICATIONS ARE THAT SCATTERED THUNDERSTORMS WILL DEVELOP BY
MID AFTERNOON AND MOVE EASTWARD INTO SOUTHEAST KS/EASTERN OK DURING
THE EVENING.  SUPERCELLS CAPABLE OF HAIL AND PERHAPS A TORNADO ARE
POSSIBLE.  VERTICAL SHEAR PROFILES AND FORCING ARE VERY FAVORABLE
FOR ORGANIZED SEVERE STORMS.  HOWEVER...NARROW INSTABILITY AXIS AND
LIMITED LOW LEVEL MOISTURE ARE EXPECTED TO PRECLUDE A MORE
SIGNIFICANT SEVERE WEATHER EVENT IN THIS AREA TODAY.

...EASTERN OK/WESTERN AR TONIGHT...
MORNING SURFACE ANALYSIS SHOWS MAIN SURFACE WARM FRONT EXTENDING
FROM SOUTH-CENTRAL TX INTO THE WESTERN GULF OF MEXICO. THIS
BOUNDARY IS THE NORTHERN EXTENT OF TROPICAL MOISTURE /DEWPOINTS AOA
65F/.  ALL MODEL GUIDANCE SUGGESTS THIS AIR MASS WILL RETURN RAPIDLY
NORTHWARD TODAY...REACHING SOUTHEAST OK AND WESTERN AR AROUND/AFTER
00Z.  THE STRONGEST FORCING ASSOCIATED WITH THE POWERFUL UPPER
TROUGH WILL REMAIN NORTH OF THIS REGION.  HOWEVER...IT CURRENTLY
APPEARS LIKELY THAT CAPPING INVERSION WILL WEAKEN SUFFICIENTLY OVER
THE ARKLATEX REGION AND SOUTHEAST OK FOR SCATTERED EVENING
THUNDERSTORM DEVELOPMENT.  VERY STRONG LOW LEVEL WARM ADVECTION WILL
YIELD LOW LEVEL AND DEEP LAYER VERTICAL SHEAR PROFILES FAVORABLE FOR
DISCRETE SUPERCELLS AND TORNADOES /3KM HELICITY OF 200-500 M2/S2 AND
6KM SHEAR OF 40-60 KNOTS/.  THIS REGION WILL BE CLOSELY MONITORED
THROUGH THE DAY WITH THE POTENTIAL FOR AN UPGRADE TO MODERATE RISK
IF LOW LEVEL MOISTURE/INSTABILITY TRENDS APPEAR STRONGER THAN
FORECAST.

..HART/GRAMS.. 09/21/2006