FXUS63 KMPX 151138
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
538 AM CST TUE DEC 15 2009

.AVIATION... /12Z TAF ISSUANCE/ 

A RIDGE OF HIGH PRESSURE OVER THE DAKOTAS WILL MOVE EAST ACROSS THE
TAF SITES DURING THE FORECAST PERIOD WITH VFR CONDITIONS PREVAILING.
WEST WINDS TODAY IN THE 8 TO 12 KNOT RANGE...BACKING TO THE SOUTHEAST
THIS EVENING AND DIMINISHING TO 3 TO 6 KNOTS.

KAXN...BKN150 DEVELOPING BY THIS EVENING AS MOISTURE INCREASES ON
THE BACKSIDE OF THE HIGH. FURTHER LOWER TO OVC100 OVERNIGHT. SMALL
THREAT FOR MVFR CEILING AT OR JUST BEYOND THE END OF THE TAF
PERIOD AS SURFACE WARM FRONT DEVELOPS ACROSS CENTRAL MN.  

KSTC...BKN-OVC120-150 DEVELOPING 16/02Z-06Z.

KRWF...BKN-OVC120-150 DEVELOPING 16/02Z-06Z.

KMSP...BKN-OVC120-150 DEVELOPING 16/04Z-08Z.

KRNH...BKN-OVC120-150 DEVELOPING 16/04Z-08Z.

KEAU...BKN-OVC150 DEVELOPING 16/04Z-08Z.

&&

.DISCUSSION... /ISSUED 331 AM CST TUE DEC 15 2009/

SURFACE ANALYSIS THIS MORNING SHOWS 1036MB HIGH CENTERED FROM ERN 
NEB NW BACK INTO ERN MONTANA. THIS PUTS THE CWA ON COLD SIDE OF 
HIGH...BUT TEMPS HAVE BEEN SOMEWHAT SLUGGISH TO RESPOND...THANKS IN 
LARGE PART TO WEAK SHORTWAVE MOVING ACROSS NRN MN THAT HAS SPREAD 
CLOUD COVER ACROSS THE AREA. THE BACK EDGE OF CLOUDS HAS MOVED OUT 
OF WRN MN AND THE DAKOTAS...BUT EVEN HERE TEMPS HAVE BEEN SLOW TO 
DROP...SO LIKELY NOT GOING TO SEE TEMPS THIS MORNING AS COLD AS 
ORIGINALLY THOUGHT. THIS HAS ALSO RESULTED IN WIND CHILL VALUES 
BEING A BIT WARMER THAN FORECAST...WITH ONLY A HANDFUL OF SITES OUT 
WEST GETTING TO OR BELOW -25F THIS MORNING...THOUGH MANY AIRPORTS 
ACROSS MN ARE SHOWING WIND CHILLS OF -20F OR LESS...SO WILL KEEP THE 
WIND CHILL ADVISORY GOING THROUGH 17Z. DESPITE THE WARMER STARTING 
POINT THOUGH...MIX DOWN TOOL TO H95 FROM BOTH 00Z NAM/GFS STILL 
SUGGESTS TEMPS WILL STRUGGLE TO SNEAK ABOVE ZERO THIS 
AFTERNOON...WITH AREAS FROM LITTLE FALLS BACK TO MORRIS LIKELY NOT 
EVEN SEEING ZERO. THIS IS MUCH COOLER THAN THE MAV...BUT FAIRLY 
SIMILAR TO COOLER MET GUIDANCE.

FOR TONIGHT...CENTER OF SFC HIGH WILL SLIP INTO ERN IL...WHICH WILL 
PUT CWA INTO SRLY FLOW AND RATHER IMPRESSIVE WAA. IN FACT...BY 12Z 
WEDNESDAY H85 TEMPS ARE FORECAST BY ALL GUIDANCE TO HAVE WARMED TO 
NEAR 0C IN THE SW...THIS IS UP FROM VALUES AROUND -17C THIS MORNING. 
SREF PLUMES FROM BOTH THE 21Z AND 03Z RUNS SHOW ALL SITES WARMING 
OVERNIGHT...WITH THE WARMING STARTING AT MVE AROUND 00Z...MSP 03Z... 
AND EAU 06Z. NEEDLESS TO SAY...HAVE NON-DIURNAL CURVE FOR TEMPS 
TONIGHT...FOLLOWING THE SREF TREND. WILL ALSO HAVE TO EYE ANOTHER 
WEAK SHORTWAVE PASSING TO THE NORTH OVERNIGHT. GFS SHOWING DECENT 
FGEN FROM H85-H7 ON ELEVATED WARM FRONT AND MOIST UPGLIDE ON THE 
280/285K SFCS NOSING DOWN TOWARD CENTRAL MN. SREF PROBS ALSO HINTING 
AT SOME LOW END SNOW CHANCES NOSING DOWN INTO NRN CWA WEDNESDAY 
MORNING...BUT OUTSIDE OF THAT...NO OTHER GUIDANCE HINTING AT THIS 
WAVE DOING MUCH...SO KEPT FORECAST DRY FOR NOW.

FOR THE REST OF THE WEEK...H5 RIDGE FORECAST TO STRENGTHEN ACROSS 
THE ROCKIES...WITH DEEP H5 LOWS SETTING UP NE OF MAINE AND OVER 
ALASKA AS A STRONG REX BLOCK HIGH DEVELOPS FROM THE NRN ATLANTIC 
ACROSS GREENLAND AND INTO NRN CANADA. GFS/ECMWF/GEM ALL HANDEL THIS 
COMPLEX FLOW PATTERN IN SLIGHTLY DIFFERENT WAYS...BUT ALL INDICATE 
POTENTIAL SHORTWAVE PASSAGES THURSDAY AND AGAIN FRIDAY. NONE OF 
THESE PIECES OF ENERGY LOOK ALL THAT ORGANIZED...WITH THURSDAYS 
SYSTEM AGAIN BRUSHING BY TO THE NORTH. ECMWF/GFS TAKE THE FRIDAY 
WAVE SW OF AREA...BUT NAM/GEM/SREF BRING IT AND SOME LIGHT QPF 
CLOSER TO THE AREA...SO WILL CONTINUE MENTION OF SLIGHT CHANCE OF 
-SN FROM FRIDAY INTO SATURDAY. ON SATURDAY...GFS/ECMWF BRING ANOTHER 
CANADIAN HIGH INTO THE UPPER MIDWEST...THOUGH ARCTIC AIR IS FORECAST 
TO BE OVER ASIA AND ALASKA...WHICH MEANS AIRMASS FROM SATURDAY ON 
WILL BE OF CONTINENTAL POLAR ORIGIN...STILL COLD WITH BELOW NORMAL 
TEMPERATURES...JUST NOT AS COLD AS WILL BE SEEN TODAY.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WIND CHILL ADVISORY UNTIL 11 AM CST THIS MORNING FOR ANOKA-
     BENTON-BLUE EARTH-BROWN-CARVER-CHIPPEWA-CHISAGO-DAKOTA-
     DOUGLAS-FARIBAULT-FREEBORN-GOODHUE-HENNEPIN-ISANTI-KANABEC-
     KANDIYOHI-LAC QUI PARLE-LE SUEUR-MARTIN-MCLEOD-MEEKER-MILLE 
     LACS-MORRISON-NICOLLET-POPE-RAMSEY-REDWOOD-RENVILLE-RICE-
     SCOTT-SHERBURNE-SIBLEY-STEARNS-STEELE-STEVENS-SWIFT-TODD-
     WASECA-WASHINGTON-WATONWAN-WRIGHT-YELLOW MEDICINE.

WI...NONE.
&&

$$

RAH/MPG