SWODY1
SPC AC 181625
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1125 AM CDT FRI JUN 18 2010
VALID 181630Z - 191200Z
...THERE IS A MDT RISK OF SVR TSTMS PORTIONS OF SRN AND ERN IA...NRN
MO...NRN AND WRN IL AND SRN AND ERN WI...
...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK AREA
FROM THE LWR MO AND MID MS VLYS INTO THE UPR GRT LKS...
...SYNOPSIS...
RATHER DEEP VERTICALLY STACKED LOW OVER SRN MANITOBA WILL SHIFT EWD
AND FILL WHILE THE STRONG MID/UPR WIND MAX NOW NRN PLAINS ROTATES
EWD ACROSS NRN MS VALLEY/UPR GREAT LAKES BY THIS EVENING. THE
ASSOCIATED COLD FRONT FROM THE MN ARROWHEAD SWWD TO CENTRAL NEB IS
PRECEDED BY SEVERE MCS NOW OVER WRN IA.
SINCE THE IA MCS WAS NOT ANTICIPATED BY ANY MODELS...WILL NEED TO
MOVE UP THE TIMING OF THE PRIMARY SEVERE THUNDERSTORM THREAT ACROSS
PORTIONS OF THE EARLIER OUTLOOK.
...UPPER GREAT LAKES TO MID MS VALLEY...
WITH 850MB WINDS BACKING AND INCREASING AHEAD OF THE IA MCS AND THE
COLD FRONT...A RAPIDLY MOISTENING AND DESTABILIZING AIR MASS WILL
SPREAD NEWD ACROSS WI/NRN IL THIS AFTERNOON.
EXPECT THE SEVERE MCS TO CONTINUE EWD ACROSS ERN IA/NRN IL THIS
AFTERNOON WITH A CONTINUED THREAT OF DAMAGING WINDS AS WARM SECTOR
BECOMES VERY MOIST AND UNSTABLE WITH MLCAPES AOA 3000 J/KG.
MUCH OF WI WILL ALSO BECOME VERY UNSTABLE WITH THE STRONG HEATING
AND THETAE E ADVECTION. WITH THE APPROACHING MID/UPR WIND
MAX...SHEAR PROFILES BECOME VERY FAVORABLE FOR SUPERCELLS ACROSS
PARTICULARLY THE ERN HALF OF WI WHERE THE MLCAPES WILL RANGE UPWARDS
FROM 2000 J/KG IN THE N TO NEAR 3000 J/KG SERN WI.
SEVERE THUNDERSTORMS WILL DEVELOP IN ADVANCE OF BOTH THE COLD FRONT
AND THE LEADING EDGE OF THE MCS WITH NOT ONLY DAMAGING WINDS BUT THE
POTENTIAL FOR TORNADIC SUPERCELLS AS WELL...GIVEN THE 40-50KT OF
SHEAR...PARTICULARLY ERN WI INTO WRN UPR MI.
ADDITIONAL MCS DEVELOPMENT BY THIS EVENING IN THE WAKE OF THE
CURRENT IA MCS IS LIKELY BUT THE TRACK AND INTENSITY IS HIGHLY
DEPENDENT ON WHERE BOUNDARIES WILL BE FROM CURRENT ACTIVITY.
...LWR MO VLY TO MID MS VLY THROUGH LATE TONIGHT...
OUTFLOW BOUNDARY FROM IA MCS AND/OR EXISTING COLD FRONTAL
CONVERGENCE SHOULD SERVE AS FOCI FOR ADDITIONAL...INTENSE STORM
DEVELOPMENT THIS AFTN AS SBCAPE INCREASES TO AROUND 4000 J/KG OVER
PARTS OF WRN IA/NRN MO/NE KS. ALTHOUGH DEEP SHEAR WILL BE MODEST
RELATIVE TO THAT FARTHER N...GIVEN DEGREE OF INSTABILITY ON EDGE OF
EML AND RICH MOISTURE AVAILABILITY /SFC DEWPOINTS AROUND 70 F/ WILL
BE AMPLE FOR SUSTAINED STORMS AND A FEW SUPERCELLS BEFORE ACTIVITY
CONGEALS INTO ONE OR MORE LARGE CLUSTERS. SOME VERY LARGE HAIL COULD
OCCUR OVER WRN PORTIONS OF THIS REGION DURING THE EARLY STAGES OF
STORM DEVELOPMENT.
...SRN NEB/NRN KS LATE IN PERIOD...
INCREASING WAA/MOISTURE INFLOW ATOP SHALLOW FRONTAL ZONE MAY SUPPORT
DEVELOPMENT OF SCTD ELEVATED STORMS WITH HAIL LATE TONIGHT/EARLY SAT
ALONG NERN FRINGE OF EML IN NRN KS/SRN NEB.
..HALES/STOPPKOTTE.. 06/18/2010
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