FXUS63 KMPX 260917
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
316 AM CST WED NOV 25 2009

.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 
SATELITTE 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 PRECIPITATON 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.../06Z TAF ISSUANCE/ 

MVFR CIGS REMAIN IN THE WAKE OF THE LOW PRESSURE SYSTEM EXITING TO 
THE SOUTHEAST.  SOME CYCLONIC FLOW ON THE BACKSIDE OF THE LOW WILL 
KEEP LOWER CIGS AROUND THROUGH MUCH OF THE NIGHT OUT OVER THE 
WESTERN FA.  SOME CLEARING POSSIBLE TOWARD 12Z AS DRYING/SUBSIDENCE 
CONTINUES.  TIMING OF CLEARING INTO THE EAST MORE OF A 
PROBLEM...WITH 00Z GFS SLOWING THE DRYING QUITE A BIT.  WILL FOLLOW 
LAMP GUIDANCE FOR NOW...AND IS CLOSE TO WHAT PREVIOUS FORECAST 
WAS...WITH VFR DEVELOPING OVER MN FA THROUGH 15Z AND COMING TO KEAU 
ABOUT 18Z THU.  REST OF FCST SHOULD BE QUIET WITH VFR CONDS THRU 12Z 
FRI.  SOME CIRRUS AROUND AND WINDS BECOMING MORE SOUTHERLY WITH THE 
PASSAGE OF THE SFC RIDGE. 

&&

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

$$

JM/DWE