FXUS63 KMPX 061732
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1232 PM CDT MON OCT 6 2008

.AVIATION.../18Z TAF ISSUANCE/

SCATTERING OF MVFR CIGS WILL BE FOUND DURING THE
AFTERNOON...ESPECIALLY IN AN ARC FROM WEST CENTRAL MN INTO WEST
CENTRAL WI GENERALLY NORTH OF A WARM FRONT. OTHERWISE VFR
CONDITIONS CAN BE EXPECTED UNTIL THE COLD FRONT AND TROUGH ENTER
THE WESTERN AREAS THIS EVENING. SHOWERS ARE POSSIBLE AS WELL IN
WEST CENTRAL MN NEAR THE COLD FRONT...AND OVER WEST CENTRAL
WI..IN A ZONE OF LEFT OVER MOISTURE TRANSPORT FROM LAST NIGHT.
SHOWERS WILL SPREAD INTO WESTERN MN THIS EVENING AND THEN ACROSS
THE REST OF THE AREA LATE TONIGHT AND TUESDAY MORNING...AS THE
FRONT CROSSES THE AREA...ALONG WITH INCREASING UPPER AIR SUPPORT
FROM THE SOUTHWEST. CIGS WILL DROP INTO THE IFR CATEGORY IN THE
RAIN AND SHOWER SHIELD...BUT VSBYS PRIMARILY MVFR. ISOLATED
THUNDERSTORMS ARE POSSIBLE OVER WEST CENTRAL MN THIS
EVENING...AFFECTING KAXN...KRWF...AND POSSIBLY KSTC. RAIN WILL BE
MOVING OUT OF WEST CENTRAL MN TUESDAY MORNING WITH CLEARING/LIFTING
OF CIGS.

.PREV DISCUSSION.../ISSUED 338 AM CDT MON OCT 6 2008/

NORTHERN AND SOUTHERN STREAM SHORT WAVES TO MARCH ACROSS THE
PLAINS IN TANDEM OVER THE NEXT 48 HOURS. THIS WILL DRIVE A SURFACE
COLD FRONT ACROSS THE MN CWA BY TUESDAY EVENING AND THE WI CWA BY
WEDNESDAY MORNING. GFS/NAM IN BETTER AGREEMENT WITH THE ECMWF
TONIGHT ON HAVING A LITTLE FASTER MOVEMENT WITH THE AFOREMENTIONED
FEATURES.

ONE CHANGE TO THE GRIDS OVERNIGHT INCLUDED RAISING HIGH
TEMPERATURES ABOUT A CATEGORY TODAY WITH 850 MB TEMPERATURES
RUNNING 11 TO 13 DEG C. THIS MAY NOT BE ENOUGH IF MORE BREAKS IN
THE CLOUDINESS OCCUR...ESPECIALLY SOUTHERN MN. FOR NOW HAVE HIGHS
FROM 65 TO 75 NORTH TO SOUTH TODAY. BEST RAIN CHANCES TODAY ACROSS
THE WESTERN CWA...WHICH IS CLOSER TO THE UPPER JET AND LARGE SCALE
OMEGA. LOW LEVEL FLOW IS ACTUALLY PROGGED TO BECOME ANTICYCLONIC
OVER WI AND SE MN ALONG WITH SOME DRYING IN THE COLUMN. FOLLOWED
ALONG WITH THE PREVIOUS FORECAST AND WENT DRY FOR PARTS OF WEST
CENTRAL WI THIS AFTERNOON AND TONIGHT. 4KM NSSL WRF AND NMM WRF
BOTH SHOWING A FLARE UP IN CONVECTION OVER WEST CENTRAL WI AND
EAST CENTRAL MN IN THE 14Z TO 18Z TIME FRAME THEN BASICALLY DRY
DURING THE AFTERNOON AND EVENING.

CATEGORICAL POPS STILL IN ORDER FOR WESTERN MN EARLY TONIGHT AND
FOR EASTERN MN DURING THE OVERNIGHT HOURS AS THE FRONTAL BOUNDARY
MOVES SLOWLY ACROSS THE MN CWA. PUSHED THE DRYING TREND ACROSS THE
ENTIRE MN CWA TUESDAY NIGHT AND BY AFTERNOON ON WEDNESDAY FOR WEST
CENTRAL WI. INSERTED PATCHY FOG FOR EARLY WEDNESDAY MORNING ACROSS
WESTERN MN WITH CLEARING...MOIST SOIL CONDITIONS AND SURFACE
RIDGING EXPECTED.

ONLY MINOR TWEAKS MADE BEYOND WEDNESDAY. THERE REMAINS
CONSIDERABLE DISAGREEMENT BETWEEN THE GFS AND ECMWF FOR THE LATE
WEEK AND WEEKEND PERIOD. ECMWF CONTINUES WITH A VERY DEEP TROUGH
IN THE FAR WESTERN U.S. WHILE THE GFS WOULD HAVE THIS FEATURE OVER
THE NORTHERN PLAINS. 500MB HEIGHTS PROGGED BY THE ECMWF FOR
SATURDAY ARE 5 STANDARD DEVIATIONS BELOW NORMAL. THE GFS AND EVEN
THE CMC ARE ON THE ORDER OF 3 STANDARD DEVIATIONS BELOW
NORMAL...BUT MUCH FURTHER ENE. END OF THE WEEK/WEEKEND SHOULD BE
QUITE INTERESTING.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&

$$

RAH/JPR


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