FXUS63 KMPX 261142
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
542 AM CST THU NOV 26 2009

.UPDATE...

ADDED AVIATION DISCUSSION FOR 12Z TAFS BELOW...

&&

.DISCUSSION...
THE NEAR TERM FORECAST CHALLENGE IS SKY CONDITION TODAY. LONGWAVE 
TROUGH EXTENDING FROM THE GREAT LAKES INTO SOUTH CENTRAL 
STATES...CONTINUE TO INFLUENCE THE WEATHER OVER THE WESTERN GREAT 
LAKES THIS MORNING...CYCLONIC CIRCULATION LINGER BACK OVER OUR CWA 
THIS MORNING. UPPER RIDGE OVER THE WESTERN CONUS...WILL ADVANCE EAST 
AND BUILD OVER THE UPPER MIDWEST DURING THE PERIOD.  THE LATEST 
SATELLITE IMAGERY OFF THE 11U-3.9 MICRON LOOP SHOWED SOME BREAKS IN 
THE CLOUDS OVER EXTREME WESTERN MN.  WATER VAPOR IMAGERY ALSO SHOWED 
AN UPPER LEVEL JET AND A DRY INTRUSION OVER THE WESTERN ONE THIRD OF 
MN...CLOUDS ARE EXPECTED TO CLEAR OR BREAKUP ACROSS THE WESTERN AND 
CENTRAL PORTION OF MN BEFORE NOON AND OVER WEST CENTRAL WISCONSIN 
DURING THE AFTERNOON. NAM80 INDICATED BASICALLY COLD AIR ADVECTION 
THROUGH MIDDAY OVER THE FORECAST AREA. MAX TEMPS TODAY ARE EXPECTED 
TO ONLY REACH THE 30S. 

NEXT PRECIPITATION PRODUCER...WILL BRING A THREAT OF SNOW SHOWERS OR 
SNOW FLURRIES OVER THE UPPER MIDWEST SUNDAY. CURRENT INDICATIONS ARE 
THAT THE BULK OF THE ENERGY ASSOCIATED WITH SHORTWAVE TROUGH WILL 
STAY NORTH OVER NORTHERN MN.

MEDIUM AND LONG RANGE...BOTH THE LATEST GFS AND ECMWF MODELS ARE IN 
GENERAL AGREEMENT BY KEEPING A SPLIT AIRFLOW REGIME OVER THE NORTH 
AMERICA. BY 120 HOURS...MODELS ARE HINTING AT SHORT WAVE TROUGH OVER 
THE PACIFIC NORTHWEST.  THIS TROUGH IS PROGGED TO CARVE OUT A 
LONGWAVE TROUGH OVER THE NORTHERN PLAINS/UPPER MIDWEST BY WEDNESDAY. 
AS MENTION IN EARLIER DISCUSSION...BIG CHANGE IN THE OVERALL WEATHER 
PATTERN WITH MUCH OF THE MIDWEST DEEPER IN THE COLD OR ARCTIC 
AIRMASS AS THICKNESS FIELDS OFF THE 1000-500 MB LAYER BETWEEN 
520-528 DAM. 

&&

.AVIATION.../12Z TAF ISSUANCE/ 

LOW PRESSURE WHICH BROUGHT PRECIPITATION AND CLOUDS OVER THE LAST
24 HOURS IS MOVING SLOWLY ACROSS LAKE MICHIGAN WHILE HIGH PRESSURE
RIDGING IS EASING EASTWARD ACROSS THE EASTERN DAKOTAS. MVFR 1500
TO 3000 FT CEILINGS WILL GRADUALLY MOVE SOUTHEASTWARD OUT OF THE
AREA THROUGH LATE MORNING AND EARLY AFTERNOON. ONCE THAT OCCURS
VFR CONDITIONS ARE EXPECTED THROUGH THE REMAINDER OF THE PERIOD.
BREEZY NORTHWEST WINDS THIS MORNING WILL DECREASE THROUGH THE
AFTERNOON AS THE HIGH MOVES IN THEN SHIFT TO WEST THEN SOUTHWEST
LATE THIS AFTERNOON AND EARLY THIS EVENING AND BECOME LIGHT. WINDS
WILL SHIFT TO THE SOUTH AND REMAIN LIGHT LATE TONIGHT THROUGH
DAYBREAK FRIDAY.

KAXN...BACK EDGE OF STRATUS DECK WILL MOVE ACROSS THE SITE BY 14Z
OR SO LEAVING VFR CONDS THROUGH THE REMAINDER OF THE PERIOD.

KSTC...CEILINGS WILL HOVER AROUND 2000 FT THROUGH ABOUT 16Z OR SO
BEFORE SCATTERING FOR THE REMAINDER OF THE MORNING.

KMSP...CEILINGS AT 2200 FT AT 1130Z MAY DECREASE TO 1900 OR 2000
FT OVER THE NEXT SEVERAL HOURS BEFORE SCATTERING BY LATE MORNING.
FEW-SCT CLOUDS BETWEEN 3000 AND 4000 FT MAY LINGER THROUGH THE
AFTERNOON.

KEAU...CEILINGS WILL HOLD ON LONGEST HERE. BASES WILL HOVER AROUND
2000 FT THROUGH THE MORNING WITH SCATTERING STARTING AROUND 18Z.
WILL NEED TO WATCH CLOUDS UPSTREAM ACROSS THE WESTERN END OF LAKE
SUPERIOR AND NW WI THROUGH LATE MORNING TO SEE IF THEY WILL HANG
ON AND DROP SOUTHWARD. WILL KEEP SCATTERED SKIES FOR THE MID/LATE
AFTERNOON FOR NOW.

KRNH...1500 TO 2000 FT CIGS WILL CONTINUE THROUGH 15 OR 16Z BEFORE
BEGINNING TO SCATTER LEAVING FEW-SCT CLOUDS OF 3000 TO 4000 FT FOR
THE AFTERNOON.  ..MDB..

&&

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

$$

JVM/MDB