SWODY1
SPC AC 041244
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0744 AM CDT FRI MAY 04 2007
VALID 041300Z - 051200Z
..THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON AND EVENING OVER
PARTS OF EASTERN CO...WESTERN AND CENTRAL KS...NORTHWEST OK...AND
SOUTHWEST NEB...
..THERE IS A SLGT RISK OF SVR TSTMS FROM SOUTHWEST TX INTO SD...
..THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF LA AND MS...
..CENTRAL PLAINS...
MORNING WATER VAPOR IMAGERY SHOWS BROAD UPPER TROUGH CONTINUING TO
ROTATE INTO THE PACIFIC NORTHWEST AND NORTHERN ROCKIES. STRONG
UPPER JET MAX NOW DIGGING SOUTHEASTWARD INTO THE FOUR CORNERS REGION
WILL NOSE INTO THE CENTRAL HIGH PLAINS BY THIS EVENING.
MEANWHILE...RAPID SURFACE CYCLOGENESIS IS EXPECTED OVER SOUTHEAST
CO. THIS WILL RESULT IN STRENGTHENING SOUTHERLY LOW LEVEL WINDS
THROUGHOUT THE PLAINS STATES. RECENT SURFACE ANALYSIS SHOWS
ABUNDANT LOW LEVEL MOISTURE OVER CENTRAL TX AND SOUTHERN OK...WHICH
WILL SPREAD/MIX QUICKLY NORTHWARD INTO KS TODAY. STRONG SURFACE
HEATING IS LIKELY THROUGHOUT THIS REGION TODAY AFTER MORNING LOW
CLOUDS BURN OFF...RESULTING IN AN EXTREMELY UNSTABLE AIR MASS ALONG
AND EAST OF THE DRYLINE FROM SOUTHWEST KS INTO WESTERN OK. EASTERLY
LOW LEVEL WINDS WILL ALSO ADVECT 50S DEWPOINTS WESTWARD ACROSS MOST
OF EASTERN CO BY MID AFTERNOON.
PRESENT INDICATIONS ARE THAT FIRST CONVECTION WILL BE ALONG THE
FOOTHILLS OF SOUTH-CENTRAL CO NEAR PUB. THESE STORMS WILL BE AIDED
BY EAST-NORTHEAST SURFACE WINDS AND UPSLOPE FLOW. VERTICAL SHEAR
PROFILES IN THIS AREA SUGGEST STORMS WILL RAPIDLY BECOME
SUPERCELLULAR WITH A RISK OF VERY LARGE HAIL AND A FEW TORNADOES.
ACTIVITY WILL LIKELY INCREASE IN COVERAGE DURING THE EARLY EVENING
AS STORMS SPREAD NORTHEASTWARD TOWARD NORTHWEST KS AND SOUTHWEST
NEB. TORNADO THREAT SHOULD INCREASE WITH EASTWARD EXTENT AS STORMS
MOVE INTO MORE MOIST BOUNDARY LAYER.
FARTHER SOUTH...SURFACE DRYLINE IS EXPECTED TO EXTEND FROM SOUTHWEST
KS NEAR DDC SOUTHWARD ALONG THE OK/TX BORDER. SHORTWAVE RIDGING IS
OCCURRING OVER THIS REGION THIS MORNING...RESULTING IN A
STRENGTHENING CAP AND LITTLE IN THE WAY OF CONVECTIVE THREAT UNTIL
THIS AFTERNOON. MODELS VARY ON WHETHER THE CAP CAN WEAKEN
SUFFICIENTLY DOWN THE DRYLINE FOR INITIATION THIS EVENING. HIGHEST
CONFIDENCE IS FOR STORMS TO FORM NEAR WARM FRONT-DRYLINE TRIPLE
POINT NEAR DDC AND TRACK EASTWARD DURING THE EVENING. FORECAST
SOUNDINGS IN THIS AREA SHOW EXTREME INSTABILITY AND MORE THAN
SUFFICIENT VERTICAL SHEAR PROFILES FOR SUPERCELLS CAPABLE OF VERY
LARGE HAIL...DAMAGING WINDS...AND STRONG TORNADOES. RIGHT NOW IT
APPEARS THAT DEVELOPMENT DOWN THE DRYLINE INTO OK WILL BE MUCH MORE
ISOLATED WITH A VERY CONDITIONAL SEVERE THREAT. ANY STORMS THAT CAN
FORM IN THIS AREA WILL POSE A RISK OF SIGNIFICANT SEVERE. PARTS OF
OK AND NORTHWEST TX MAY SEE CONTINUED THREAT AFTER MIDNIGHT AS LARGE
SCALE FORCING BEGINS TO OVERSPREAD THE SOUTHERN PLAINS...LEADING TO
SCATTERED THUNDERSTORM DEVELOPMENT CAPABLE OF LARGE HAIL.
..LOWER MS VALLEY...
SCATTERED STRONG THUNDERSTORMS ARE ONGOING THIS MORNING OVER PARTS
OF LA AND SOUTHERN MS. THESE STORMS ARE LIKELY TO CONTINUE
THROUGHOUT THE DAY WITH A RISK OF LOCALLY DAMAGING WINDS AND HAIL.
WILL MAINTAIN ONLY LOW SEVERE PROBABILITIES FARTHER NORTH DUE TO
UNCERTAINTIES WITH AIR MASS RECOVERY AND INSTABILITY. REFER OF MCD
NUMBER 680 FOR FURTHER DETAILS ON THIS AREA.
.HART/TAYLOR.. 05/04/2007
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