459
FXUS63 KMPX 240403
AFDMPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1100 PM CDT WED JUL 23 2008
PREV DISCUSSION
/ISSUED 247 PM CDT WED JUL 23 2008 BY WFO DLH/
THE LATEST REGIONAL SFC ANALYSIS SHOWS A LARGE AREA OF HIGH PRESSURE
OVER THE UPPER MIDWEST. HOWEVER CLOUDS HAVE BEEN INCREASING ACROSS
CNTL AND SRN MN IN ASSOCIATION WITH AN UPPER LEVEL SHORTWAVE
APPROACHING THE FCST AREA FROM THE WEST. SCATTERED SHOWERS AND
THUNDERSTORMS HAVE DEVELOPED ACROSS THE ERN DAKOTAS TODAY DUE IN
PART TO THIS SHORTWAVE. THIS ACTIVITY IS EXPECTED TO CONTINUE TO
PROPAGATE EWD OVER MINNESOTA TONIGHT...AND THEN SPREAD OVER WRN
WISCONSIN BY THURSDAY MORNING. THE NAM SHOWS MUCAPE VALUES
INCREASING TO BETWEEN 1000 AND 2000 J/KG ACROSS OUR CWA LATER
TONIGHT AND TOMORROW...WITH THE HIGHEST VALUES ACROSS OUR WRN ZONES.
VERTICAL WIND SHEAR...COINCIDENT WITH HIGHER CAPE VALUES...WILL BE
MARGINAL ACROSS THE FCST AREA...ESPECIALLY ON THURSDAY WHEN 0-3KM
SRH VALUES ARE PROGGED TO RANGE FROM 50 TO 150 M2/S2. HOWEVER THERE
SHOULD BE SUFFICIENT INSTABILITY AND WIND SHEAR TO WARRANT THE
SLIGHT RISK OF SEVERE THUNDERSTORMS AT OUTLINED IN SWODY2.
MOST OF THIS FIRST ROUND OF THUNDERSTORM ACTIVITY SHOULD PUSH OFF
TO OUR SOUTH AND EAST BY THURSDAY NIGHT. HOWEVER ANOTHER SHORTWAVE
AND COLD FRONT IS PROGGED TO REACH OUR WRN ZONES FRIDAY MORNING
AND THEN SLOWLY TRACK EWD ACROSS THE FCST AREA FRIDAY AND FRIDAY
NIGHT. THE FRONT AND DISTURBANCE WILL BRING ANOTHER CHANCE OF
SHOWERS AND THUNDERSTORMS TO THE REGION. WEAK TO MODERATE
INSTABILITY IS AGAIN EXPECTED ON FRIDAY...HOWEVER WITH A VERY WEAK
SFC PRESSURE GRADIENT...WIND SHEAR WILL BE WEAK OR NIL. THEREFORE
ATTM DO NOT EXPECT SVR STORMS FOR FRIDAY AND FRIDAY NIGHT.
TEMPERATURES WILL REMAIN AT NEAR NORMAL LEVELS OVER THE NEXT
COUPLE OF DAYS...WITH HIGHS IN THE LOWER TO MID 80S AND LOWS
GENERALLY IN THE 60S.
AVIATION
/06Z TAF ISSUANCE/
WARM ADVECTION PATTERN OVER FORECAST AREA STRENGTHENS LATER TONIGHT
AS HIGH PRESSURE MOVES OFF. A COUPLE OF AREAS OF SHOWERS MOVING
ACROSS PORTIONS OF MN...LARGELY MISSING MOST TAF SITES THE NEXT FEW
HOURS. MORE SUBSTANTIAL SHOWERS OVER SC MN. BY THURSDAY MORNING...
CEILINGS CLOSE TO MVFR COULD DEVELOP OVER WESTERN MN AND POSSIBLY AS
FAR EAST AS KMSP. SURFACE COLD FRONT A BIT DELAYED AND SHOULD MOVE
INTO WEST CENTRAL MN LATE THURSDAY AFTERNOON WITH A CHANCE OF
THUNDER DEVELOPING.
MPX WATCHES/WARNINGS/ADVISORIES
MN...NONE.
WI...NONE.
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