DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 181551
SWODY1
SPC AC 181549

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1049 AM CDT MON JUN 18 2012

VALID 181630Z - 191200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF WI AND MI...

...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF SD AND
NORTHERN NEB...

...WI/MI...
A LARGE UPPER RIDGE IS PRESENT TODAY OVER MOST OF THE
CENTRAL/SOUTHERN UNITED STATES...WHILE THE PRIMARY BAND OF
WESTERLIES ALOFT EXTENDS FROM THE PACIFIC NORTHWEST ACROSS THE
NORTHERN PLAINS INTO THE GREAT LAKES REGION. ONE SHORTWAVE TROUGH
IS EVIDENT OVER SOUTHERN MANITOBA/MN. THIS FEATURE WILL TRACK
EASTWARD ACROSS PARTS OF WI/UPPER MI LATER THIS AFTERNOON AND
EVENING. MUCH OF THIS AREA HAS BEEN AFFECTED BY AN OVERNIGHT MCS
NOW OVER LOWER MI. HOWEVER...RECENT SURFACE ANALYSES SHOW LOW LEVEL
MOISTURE RAPIDLY SPREADING NORTHWARD ACROSS WI WITH UPPER 60S
DEWPOINTS NOW INTO THE RHI AREA. CLOUDS WILL SLOW HEATING/
DESTABILIZATION IN THIS REGION...BUT AFTERNOON MLCAPE VALUES SHOULD
REACH 2000 J/KG WITH ONLY WEAK CAPPING REMAINING.

PRESENT INDICATIONS ARE THAT THUNDERSTORMS WILL INTENSIFY THIS
AFTERNOON OVER NORTHERN AND CENTRAL WI AS THE TAIL-END OF THE LARGE
SCALE ASCENT ASSOCIATED WITH THE UPPER TROUGH AFFECTS THE REGION.
MODERATE CAPE VALUES AND FAVORABLE VERTICAL SHEAR PROFILES WILL
PROMOTE A RISK OF SUPERCELLS AND BOW STRUCTURES CAPABLE OF DAMAGING
WINDS...LARGE HAIL...AND ISOLATED TORNADOES. THESE STORMS ARE
EXPECTED TO SPREAD EASTWARD INTO PARTS OF UPPER MI AND LAKE MI
DURING THE EVENING. AIR MASS DESTABILIZATION IS LESS CERTAIN
FARTHER EAST INTO NORTHERN LOWER MI SO WILL NOT EXTEND HIGHER SEVERE
PROBABILITIES INTO THIS AREA AT THIS TIME.

...SD/MN TONIGHT...
MODELS SUGGEST THAT AN INTENSE LOW LEVEL JET WILL DEVELOP THIS
EVENING OVER THE CENTRAL PLAINS. STRONG LOW LEVEL WARM ADVECTION
AND DESTABILIZATION IS EXPECTED ACROSS PARTS OF SD AND NORTHERN
NEB...LEADING TO SCATTERED THUNDERSTORM DEVELOPMENT. MODEL FORECAST
SOUNDINGS SHOW AMPLE CAPE AND VERTICAL SHEAR FOR SEVERE STORMS
CAPABLE OF LARGE HAIL.

...OH VALLEY...
A PLUME OF LOW/MID LEVEL MOISTURE EXTENDS ACROSS THE MID/UPPER OH
VALLEY WITH DEWPOINTS IN THE MID 60S. BROKEN CLOUDS WILL SOMEWHAT
HINDER DAYTIME HEATING...BUT SUFFICIENT DESTABILIZATION IS EXPECTED
FOR SCATTERED AFTERNOON THUNDERSTORM DEVELOPMENT. WEAK MID LEVEL
WINDS WILL LIMIT CONVECTIVE ORGANIZATION...BUT ISOLATED CELLS MAY
PRODUCE LOCALLY GUSTY WINDS AND HAIL.

..HART/MOSIER.. 06/18/2012

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