Day 1 Convective Outlook

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0729 AM CDT SUN MAY 25 2008
VALID 251300Z - 261200Z
...THERE IS A MDT RISK OF SVR TSTMS OVER PORTIONS OF EASTERN
MN...WESTERN WI...AND EXTREME WESTERN UPPER MI...
...THERE IS A MDT RISK OF SVR TSTMS OVER MUCH OF CENTRAL AND
NORTHEAST KS...SOUTHEAST NEB...NORTHWEST MO...AND SOUTHWEST IA...
...THERE IS A SLGT RISK OF SVR TSTMS FROM WEST TX...ACROSS MUCH OF
THE CENTRAL PLAINS...INTO THE WESTERN GREAT LAKES REGION...
...AN ACTIVE SEVERE WEATHER EVENT IS EXPECTED THIS AFTERNOON THROUGH
TONIGHT ALONG AN AXIS FROM NORTHERN WI INTO KS...
...MN/WI/WRN UP...
DEEP SOUTHWESTERLY FLOW IS PRESENT TODAY OVER THE WESTERN GREAT
LAKES AND UPPER MIDWEST REGION. SOUTHERLY WINDS AT THE SURFACE ARE
DRAWING MOISTURE NORTHWARD WITH DEWPOINTS RISING THROUGH THE 60S
OVER IA/EASTERN SD/SOUTHWEST MN. THIS AREA SHOULD SEE RATHER STRONG
HEATING BY LATE MORNING/EARLY AFTERNOON AS LOW CLOUDS
DISSIPATE...LEADING TO A MODERATELY UNSTABLE AIR MASS. FORECAST
SOUNDINGS IN THIS AREA SHOW STEEP MID LEVEL LAPSE RATES AND MLCAPE
VALUES OF 1000-2000 J/KG. SCATTERED THUNDERSTORMS ARE EXPECTED TO
DEVELOP ALONG/AHEAD OF APPROACHING COLD FRONT THAT WILL SWEEP INTO
MN DURING THE AFTERNOON. THESE STORMS WILL TRACK EASTWARD ACROSS
PARTS OF WI AND INTO WESTERN UPPER MI DURING THE EVENING. VERTICAL
SHEAR PROFILES IN THIS AREA SUGGEST A RISK OF SUPERCELLS CAPABLE OF
VERY LARGE HAIL AND A FEW TORNADOES /SOME POSSIBLY STRONG/.
...KS/NEB/MO/IA...
A LARGE COMPLEX OF HIGH-BASED CONVECTION AND ASSOCIATED HEAT BURSTS
HAVE BEEN AFFECTING PARTS OF OK/KS OVERNIGHT. THIS ACTIVITY HAS
DISRUPTED LOW LEVEL MOISTURE RETURN INTO KS. NEVERTHELESS...PRESENT
INDICATIONS ARE THAT A MOIST AND VERY UNSTABLE AIR MASS WILL BECOME
ESTABLISHED OVER MUCH OF THIS REGION BY LATE AFTERNOON WITH
DEWPOINTS IN THE MID/UPPER 60S AND MLCAPE VALUES OVER 2500 J/KG.
SCATTERED HIGH-BASED THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG
SURFACE DRY/TROUGH LINE AND PROPAGATE EASTWARD INTO THE MOIST AXIS
THROUGH THE EARLY EVENING. VERY STEEP MID LEVEL LAPSE RATES /SUCH
AS SEEN ON 12Z AMA SOUNDING/ AND INCREASINGLY FAVORABLE LOW/DEEP
LAYER VERTICAL SHEAR AFTER 21Z WILL PROMOTE SUPERCELL STORMS CAPABLE
OF VERY LARGE HAIL...DAMAGING WINDS...AND A FEW TORNADOES. STORMS
ARE EXPECTED TO GROW UPSCALE INTO A LINEAR MCS DURING THE EVENING
AND ACCELERATE EASTWARD ACROSS NORTHERN KS AND SOUTHEAST
NEB...EVENTUALLY MOVING INTO NORTHWEST MO AND SOUTHWEST IA AFTER
MIDNIGHT. WIDESPREAD DAMAGING WINDS AND HAIL WILL BE THE MAIN
THREATS WITH THIS ACTIVITY.
FROM THE OK PANHANDLE SOUTHWARD ACROSS WEST TX...FULL SUNSHINE IS
EXPECTED ALONG THE SURFACE DRYLINE. THIS WILL LIKELY LEAD TO A
PERIOD OF LATE AFTERNOON AND EVENING THUNDERSTORMS ALONG THIS AXIS.
PRESENT INDICATIONS ARE THAT STORMS WILL REMAIN IN A RELATIVELY
NARROW CORRIDOR NEAR THE DRYLINE BEFORE DIMINISHING AFTER DARK.
LARGE HAIL AND DAMAGING WINDS WOULD BE THE MAIN THREAT WITH THESE
STORMS.
..HART/GRAMS.. 05/25/2008