SWODY1
SPC AC 080100
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0800 PM CDT SAT JUL 07 2007
VALID 080100Z - 081200Z
..THERE IS A SLGT RISK OF SVR TSTMS TONIGHT FROM NRN MN INTO UPPER
MI....
..SYNOPSIS...
MID/UPPER LEVEL RIDGE REMAINS THE MAIN BLOCK ANCHORED OVER THE SWRN
U.S. AND FORCING MAIN BAND OF WESTERLIES ACROSS THE SRN TIER OF WRN
AND CENTRAL CANADA THEN SEWD INTO A MID LEVEL TROUGH OVER NEW
ENGLAND. LATEST SATELLITE IMAGE SHOWS A CONVECTIVE COMPLEX THAT IS
CURRENTLY NE OF LK SUPERIOR MOVING SEWD AND SHOULD BE APPROACHING
NERN NY JUST AROUND THE END OF THE PERIOD.
LATEST SURFACE ANALYSIS SHOWS MAIN FRONTAL BOUNDARY EXTENDS FROM
SERN MANITOBA SWWD INTO NCENTRAL ND AND NERN MT. IT LOOKS THAT MID
LEVEL RIDGING EVIDENT OVER MN HAS HELD MID LEVEL CAPPING INVERSION
IN PLACE. BUT...CONVECTION OVER WRN SD AT THIS TIME MAY BUILD ALONG
THE APPROACHING COLD FRONT AND BRING ELEVATED TYPE STORMS INTO NRN
MN AND UPPER MI LATER TONIGHT MAINLY AFTER 08/06Z.
..NRN MN INTO UPPER MI...
LOWERED PROBABILITIES FOR THE REMAINDER OF THE PERIOD AS MODELS LOOK
TO HAVE OVERPLAYED THE CONVECTION FOR THIS EVENING WITH THE GFS
VERIFYING THE BEST OVER THE PAST 24 HOURS. SFC LOW JUST N OF THE
NWRN MN BORDER WILL MOVE EWD TOWARDS THE INL VICINITY BY 08/06Z WITH
COLD FRONT TRAILING SWWD ACROSS NERN SD INTO E CENTRAL WY. MODELS
CONTINUE TO DEVELOP LLJ OF 35-40 KT FROM NWRN KS INTO SERN SD THEN
NEWD INTO THE MN ARROWHEAD BY 08/06Z. MID LEVEL JET OF 55-65 KT
WILL BE EXTENDING EWD ACROSS SRN ONTARIO...BUT 500 MB TEMPERATURE
AROUND -8C INDICATES CAPPING INVERSION STILL HOLDING THROUGH THIS
AREA. NOW...AIR MASS SEEMS VERY UNSTABLE WITH MLCAPES OF 3500-4500
J/KG AIDED BY TEMPERATURE IN THE MID 90S AND DEW POINTS IN THE
LOW/MID 70S. THUS...STILL BELIEVE THAT SCATTERED THUNDERSTORMS CAN
STILL DEVELOP IN THE VICINITY OF THE APPROACHING FRONTAL BOUNDARY
TONIGHT AND GIVEN THAT MID LEVEL LAPSE RATES ARE AROUND
8.5C/KM...THIS ACTIVITY COULD PRODUCE SOME DAMAGING WINDS.
..S CENTRAL MT INTO WRN SD...
ELEVATED STRONG/SEVERE THUNDERSTORMS ARE OCCURRING JUST S OF THE E-W
FRONTAL BOUNDARY THRU THIS AREA WITHIN NWRN QUADRANT OF ANTICYCLONIC
FLOW. AIR MASS IS MODERATELY UNSTABLE WITH MLCAPES TO 2000 J/KG
WITH ASSOCIATED LOW/MID LEVEL LAPSE RATES ESTIMATED AROUND 9C/KM.
THUS...THIS ELEVATED ACTIVITY IS EXPECTED TO CONTINUE THRU 08/06Z
BEFORE WEAKENING DUE TO LOSS OF DAYTIME INSOLATION.
..SERN U.S. AND FL...
MUCH OF THE ACTIVITY OVER SRN AL HAS BEEN WEAKENING LAST FEW HOURS
WITH A FEW ISOLATED STRONG STORMS AROUND MOB. STRONGEST ACTIVITY IS
MERGING AT THIS TIME AROUND CENTRAL FL FROM MLB SWWD N OF LK
OKEECHOBEE. THIS ACTIVITY IS ALSO EXPECTED TO DIMINISH NEXT SEVERAL
HOURS WITH LOSS OF DAYTIME HEATING.
.MCCARTHY.. 07/08/2007
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