DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 241632
SWODY1
SPC AC 241630

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1130 AM CDT THU MAY 24 2012

VALID 241630Z - 251200Z

...THERE IS A MDT RISK OF SVR TSTMS OVER NERN IA...EXTREME SERN
MN...AND MUCH OF WI...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE LOWER MO VALLEY INTO
THE CENTRAL PLAINS...

...NERN IA/EXTREME SERN MN/MUCH OF WI...
WATER VAPOR IMAGERY INDICATES A STRONG UPPER SHORT WAVE TROUGH
MOVING NEWD OVER ERN NEB. THIS SYSTEM IS EXPECTED TO PROGRESS INTO
THE UPPER MS VALLEY BY THIS EVENING AND CONTINUE ACROSS THE UPPER
GREAT LAKES TONIGHT AS AN UPSTREAM LOW DEVELOPS SWD ALONG THE NRN
PACIFIC COASTAL REGION. THIS TROUGH WILL BECOME MORE NEGATIVELY
TILTED WITH TIME AS IT LIFTS NEWD...PROVIDING INCREASING DIVERGENCE
ALOFT. THIS WILL RESULT IN THE SURFACE LOW CURRENTLY NEAR OMA TO
DEEPEN AS IT MOVES NNEWD...REACHING WRN LAKE SUPERIOR THIS EVENING
AND CONTINUING INTO ONTARIO TONIGHT. A SURFACE COLD FRONT EXTENDING
SWD FROM THE LOW WILL ACCELERATE INTO THE UPPER MS VALLEY THIS
AFTERNOON BEFORE REACHING LOWER MI LATE TONIGHT.

VERY STRONG WINDS ALOFT ARE ASSOCIATED WITH THE MIDWEST
TROUGH...WITH A 50 KT LOW LEVEL JET OVER THE LOWER MO VALLEY
FORECAST TO STRENGTHEN AS IT MOVES NWD INTO WI THIS
AFTERNOON...WHILE AN 80-90 KT MID LEVEL JET STREAK CURRENTLY OVER
THE CENTRAL ROCKIES/HIGH PLAINS LIFTS NEWD TOWARD THE UPPER MS
VALLEY. THIS WILL CREATE VERY STRONG LOW/MID LEVEL SHEAR OVER THE
WARM SECTOR AHEAD OF THE COLD FRONT SUPPORTIVE OF SEVERE STORMS.
THE PRIMARY LIMITING FACTOR REMAINS LOW LEVEL MOISTURE WITH SURFACE
DEW POINTS LIKELY REACHING THE 55-60F RANGE PRIOR TO FRONTAL
PASSAGE. A PLUME OF MODERATELY STEEP MID LEVEL LAPSE RATES ALSO
EXTENDS OVER THE WARM SECTOR AND IS CONTRIBUTING TO GREATER
INSTABILITY GIVEN THE SOMEWHAT LIMITED LOW LEVEL MOISTURE. ENHANCED
DIABATIC HEATING AHEAD OF THE CLOUD SHIELD OVER THE UPPER MS VALLEY
WILL AID IN FURTHER DESTABILIZATION WITH MLCAPE REACHING 1000-1500
J/KG THIS AFTERNOON.

CURRENT ELEVATED STORMS OVER NWRN WI ARE EXPECTED TO MOVE RAPIDLY
NEWD AND POSE A RISK OF HAIL INTO EARLY AFTERNOON. THESE STORMS
WILL ALSO BE MONITORED FOR THE POTENTIAL TO BECOME SURFACE BASED
THIS AFTERNOON...WHICH WOULD INCREASE THE LIKELIHOOD OF STRONG WIND
GUSTS. ADDITIONAL STORMS ARE EXPECTED TO DEVELOP NEAR THE COLD
FRONT FROM NERN IA INTO WRN WI BY MID AFTERNOON. THE FAVORABLE WIND
SHEAR WILL PROMOTE DEVELOPMENT OF FAST MOVING SUPERCELLS AND BOW
ECHO STRUCTURES CAPABLE OF PRODUCING DAMAGING WIND GUSTS...LARGE
HAIL...AND TORNADOES. THE STORMS ARE LIKELY TO DEVELOP INTO ONE OR
MORE BOWING LINE SEGMENTS BY LATER AFTERNOON OR EVENING...WITH THE
SEVERE THREAT TRANSITIONING INTO PRIMARILY A WIND DAMAGE SCENARIO AS
BOWING SEGMENTS MOVE RAPIDLY NEWD THROUGH THE EVENING HOURS. THE
ACTIVITY IS EXPECTED TO SLOWLY DIMINISH IN INTENSITY AFTER 03-6Z.

...CENTRAL PLAINS LATE TONIGHT...
SSWLY LLJ WILL STRENGTHEN OVER MUCH OF KS AND WRN MO LATE TNGT IN
RESPONSE TO DIURNAL INFLUENCES AND TO THE CONTINUED ESE
ADVANCE OF UPR LOW INTO NRN CA AND THE NRN GREAT BASIN. THIS
STRENGTHENING WILL OCCUR ATOP TRAILING...SW END OF SAME FRONTAL ZONE
THAT WILL CROSS THE UPR MS VLY LATER TODAY. COUPLED WITH THE
ARRIVAL OF FAIRLY SUBSTANTIAL MOISTURE RETURN /P.W. AOA 1.25 INCHES/
AND WITH THE CONTINUED PRESENCE OF 40-50 KT WSWLY SHEAR ABOVE THE
FRONTAL SFC...SETUP MAY SUPPORT ELEVATED TSTMS AFTER 06-09Z WITH
HAIL AND PERHAPS LOCALLY STRONG WIND GUSTS.

...CNTRL/S FL...
SCTD TSTMS EXPECTED THIS AFTN IN ZONE OF STRONG HEATING...HIGH
PW...AND UPR DIVERGENCE BENEATH SWLY HIGH LVL JET STREAK. THESE MAY
YIELD A FEW INSTANCES OF SVR WIND/HAIL...MAINLY ALONG SEA BREEZE
BOUNDARY INTERSECTIONS.

...MID ATLANTIC INTO PARTS OF CAROLINAS...
TROPICAL MOISTURE SPREADING NWD/CONVERGING BENEATH RESIDUAL AXIS OF
RELATIVELY COOL MID LVL TEMPS MAY SUPPORT A FEW DIURNAL STORMS/STORM
CLUSTERS WITH LOCALLY SVR WIND/MARGINALLY SVR HAIL. CONVECTION WILL
BE ENHANCED BY WEAK UPPER VORTICITY MAX MOVING NNEWD OVER THE WRN
CAROLINAS.

..WEISS/GARNER.. 05/24/2012

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