SWODY1
SPC AC 231630
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1130 AM CDT WED MAY 23 2007
VALID 231630Z - 241200Z
..THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF THE NORTHERN TX
PANHANDLE...NORTHWEST OK...AND SOUTHWEST KS...
..THERE IS A SLGT RISK OF SVR TSTMS FROM NORTHEAST NM INTO WESTERN
IA...
LARGE UPPER TROUGH IS PRESENT THIS MORNING OVER THE WESTERN UNITED
STATES...WITH WATER VAPOR IMAGERY SHOWING STRONG SHORTWAVE TROUGH
MOVING EASTWARD OVER SOUTHEAST UT. THIS FEATURE IS FORECAST TO MOVE
INTO SOUTHERN CO THIS AFTERNOON AND BEGIN AFFECTING THE CENTRAL
HIGH PLAINS. MORNING SURFACE ANALYSIS SHOWS SURFACE FRONT EXTENDING
ROUGHLY FROM P28-GAG-PVW. COMBINATION OF APPROACHING UPPER TROUGH
AND STRONG HEATING ACROSS TX/OK PANHANDLES WILL RESULT IN RAPID
RETREAT OF BOUNDARY THIS AFTERNOON AND EVENING. BY 00Z...WEST EDGE
OF DEEPER LOW LEVEL MOISTURE WILL LIKELY EXTEND FROM NORTH CENTRAL
TX PANHANDLE NORTHWARD. THIS MAY SET THE STAGE FOR A REGIONAL
OUTBREAK OF SEVERE THUNDERSTORMS THIS EVENING FROM THE TX PANHANDLE
INTO SOUTH CENTRAL KS...WITH A RISK OF VERY LARGE HAIL AND ISOLATED
STRONG TORNADOES.
..CO...
STRONG DYNAMIC FORCING WILL SPREAD ACROSS THE MOUNTAINS OF SOUTHERN
CO AND INTO THE ADJACENT PLAINS BY EARLY THIS AFTERNOON. STRONG
DAYTIME HEATING WILL RESULT IN STEEP LOW LEVEL LAPSE RATES AND
MARGINAL INSTABILITY /MLCAPE VALUES BELOW 500 J/KG/.
HOWEVER...RATHER COLD THERMODYNAMIC PROFILES AND STRONG VERTICAL
SHEAR WILL PROMOTE A RISK OF STRONG/SEVERE STORMS CAPABLE OF HAIL
AND DAMAGING WINDS. ACTIVITY WILL LIKELY INCREASE IN AREAL COVERAGE
AND INTENSITY AS IT SPREADS EASTWARD THROUGH THE EVENING ACROSS
SOUTHEAST CO AND INTO THE WESTERN TX/OK PANHANDLES.
..TX/OK/KS...
OPERATIONAL AND EXPERIMENTAL MESOSCALE MODEL GUIDANCE GENERALLY
AGREE THAT VERY MOIST/UNSTABLE AIR MASS WILL RETURN NORTHWESTWARD
INTO THE TX/OK PANHANDLES AND SOUTHWEST KS BY EARLY EVENING.
SUFFICIENT CAP WILL SUPPRESS DEEP CONVECTION UNTIL AFTER 21Z...WHEN
POTENTIAL FOR ISOLATED THUNDERSTORMS WILL INCREASE. AREAL COVERAGE
OF STORMS IS NOT EXPECTED TO BE PARTICULARLY GREAT.
HOWEVER...FORECAST SOUNDINGS IN THIS REGION SHOW IMPRESSIVE
HODOGRAPHS /EFFECTIVE HELICITY VALUES OVER 250 M2/S2 AND EFFECTIVE
SHEAR OF 35-50 KNOTS/ FAVORABLE FOR RAPID SUPERCELL DEVELOPMENT.
ANY STORM THAT CAN ANCHOR ALONG RETREATING BOUNDARY WILL ALSO BE IN
ENVIRONMENT OF LOW LCLS AND ENHANCED CONVERGENCE/VORTICITY. STRONG
TORNADOES ARE CERTAINLY A POSSIBILITY WITH STORMS ALONG THE
BOUNDARY. OTHERWISE...STORMS WILL INCREASE IN COVERAGE AFTER DARK
AS UPPER TROUGH APPROACHES WITH A CONTINUED RISK OF ISOLATED
TORNADOES AND VERY LARGE HAIL.
..KS/NEB/IA...
ISOLATED STRONG/SEVERE STORMS ARE POSSIBLE EARLY THIS AFTERNOON
ALONG SURFACE BOUNDARY EXTENDING FROM SOUTHEAST NEB INTO CENTRAL KS.
FORECAST SOUNDINGS IN THIS AREA SHOW RELATIVELY STEEP MID LEVEL
LAPSE RATES AND MODERATE INSTABILITY...DESPITE RATHER WEAK LARGE
SCALE SUPPORT. LATER TONIGHT...MORE WIDESPREAD THUNDERSTORMS ARE
LIKELY TO OVERSPREAD REGION FROM THE WEST...WITH PERHAPS A GREATER
THREAT OF HAIL AND DAMAGING WINDS.
.HART/CROSBIE.. 05/23/2007
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