271 
FXUS63 KMPX 250502
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1102 PM CST SUN JAN 24 2010

.UPDATE...FOR 06Z AVIATION DISCUSSION BELOW

&&

.DISCUSSION.../ISSUED 354 PM CST SUN JAN 24 2010/

THE FORECAST CHALLENGES CENTER ON WINDS...FALLING
TEMPERATURES...AND SNOW POTENTIAL LATE TONIGHT INTO MONDAY.

VERY IMPRESSIVE SYNOPTIC SCALE LOW LIFTING NORTH INTO THE UPPER
GREAT LAKES. SURFACE PRESSURE AT 982 MB AND CONTINUING TO FURTHER
DEEPEN WITH MOST APPRECIABLE SNOWFALL LIFTING UP INTO FAR NRN WI
AND THE MN ARROWHEAD. AT 500 MB THE LOW REMAINS TRIPLE
BARRELED...WITH SEVERAL VORTICES SPINNING AROUND THE UPPER
MIDWEST. AS THESE PHASE TONIGHT...STRONG COLD AIR ADVECTION WILL
BE WRAPPED INTO THIS SYSTEM FROM THE NORTH. THIS WILL BE A DRIVING
FORCE FOR STRONG WINDS SPREADING FROM WEST TO EAST TONIGHT INTO
MONDAY. THIS HAS LED TO A WIND ADVISORY ISSUANCE. IN
ADDITION...THE VORTICES AND ASSOCIATED SYSTEM TROWAL /TROUGH OF
WARM AIR ALOFT/...HAVE WARRANTED KEEPING HIGH SNOW PROBABILITIES
FOR MONDAY. THE COMBINATION OF THIS FALLING SNOW AND THE BLOWING
OF THE FRESHLY FALLEN SNOW FROM SATURDAY...HAS LED TO A WINTER
WEATHER ADVISORY ISSUANCE IN PARTS OF WEST CENTRAL MN.

THE DETERMINISTIC AND ENSEMBLE MODELS ARE IN FAIRLY GOOD AGREEMENT
WITH TIMING OF THIS SYSTEM OCCLUSION AND MOVEMENT THROUGH THE NEXT
48 HOURS. THE TROWAL POINTING INTO THE AREA FROM THE NNE WILL FEED
MOISTURE AND ASCENT INTO THE AREA THROUGH TONIGHT. MID-LEVEL DRY
AIR IS PRONOUNCED ON WATER VAPOR AND CONTINUING THROUGH MUCH OF
THIS EVENING. THIS MAY POSSIBLY STIFLE SOME OF THE ICE NUCLEI...SO
HAVE ADDED FREEZING DRIZZLE CHANCE...MAINLY THIS EVE. PRESSURE
RISES AND COLD AIR ADVECTION BEGIN TO ARRIVE IN WEST CENTRAL
MINNESOTA OVERNIGHT SO BEGAN WIND ADVISORY THEN.

THE STRONGEST COLD AIR ADVECTION IN THE 1000-850 MB LAYER PUSHES
IN MONDAY MORNING ACROSS THE WEST AND SOUTH. THIS ENHANCES THE LOW
LEVEL LAPSE RATES TO DRY ADIABATIC THROUGH THE LOWEST 3 KFT...WITH
MOMENTUM TRANSFER IN THE MIXING ALLOWS FOR THE POTENTIAL OF 40-50
MPH GUSTS. THIS IS SHOWN ON SOME OF THE NAM SOUNDINGS FOR ALMOST
THE ENTIRE MN CWA. THE STRONGEST WINDS THOUGH SHOULD STILL END UP
EVOLVING IN THE FAVORED WEST CENTRAL AND SOUTH CENTRAL CWA...WITH
THE HIGHER RANGE GUSTS TO NEAR 50 MPH ALONG AND ON THE LEE SIDE OF
BUFFALO RIDGE. SREF PROBABILISTIC GUIDANCE PINGS THIS AREA FOR 34
KT OR GREATER WINDS. ALSO...SIMILAR ANALOGS TO THE 00Z AND 12Z GFS
FORECASTS FROM THE COOPERATIVE INSTITUTE FOR PRECIP STUDIES /CIPS/
INDICATE THE WEST CENTRAL AND SOUTH CENTRAL HAD THE HIGHEST
WINDS IN SIMILAR EVENTS...IN THE 27-37 KT RANGE. 

FOR DAYS...THE MODELS HAVE INDICATED TEMPS FALLING ON MONDAY WITH
THE IDEAL COLD AIR ADVECTION SETUP AND HAVE ADAPTED THE TREND
GENERALLY FROM THE NAM MODEL. THE SREF 2M TEMPS INDICATE ALL
MEMBERS DROPPING QUICKLY THROUGH THE MORNING IN WRN AND SRN MN AND
THEN ACROSS THE REMAINDER OF THE AREA QUICKLY MON AFTERNOON AND
EVE. 

FOR SNOW ON MONDAY...A VORT MAX IS PEGGED TO DROP SSE THROUGH THE
AREA AT THE SAME TIME AS THE STRONGEST COLD AIR ADVECTION IN THE
LOW LEVELS. THE TROWAL IS CONTINUING TO FEED MOISTURE IN AT THAT 
TIME WITH PWATS NOT DROPPING UNTIL LATE IN THE DAY. SO CONTINUE
CATEGORICAL POPS ON MON. ACCUMS OF UP TO 2 INCHES POSSIBLE IN
CENTRAL AND EASTERN MN INTO WESTERN WI. WITH SOMEWHAT LIGHTER WINDS
IN SOME OF THAT AREA...DID NOT FEEL THAT A WINTER WEATHER ADVISORY
IS NEEDED FOR EASTERN PORTION OF THE AREA. AGAIN...MAINLY CONFINED
ADVISORY TO THE AREA HAVING SEEN THE FRESH SNOW ON SAT.

SYSTEM PULLS OUT LATER MON NIGHT INTO TUES. SOME GOOD SUPPRESSION
IN THE MID-LEVELS ALLOWING FOR SOME LIKELY SUNSHINE BY TUES.
TEMPS WILL BE BELOW NORMAL TUE THROUGH FRI AS COLD AIR REINFORCES
ITSELF WED NIGHT INTO THU AS DEEP WAVE DROPS OVER ONTARIO.
CYCLONIC FLOW MAY SPIT OUT SOME FLURRIES. FOR NOW HAVE INCREASED
SKY COVER. GENERALLY NO LARGE IMPACTING SYSTEM AFTER THE CURRENT
ONE THROUGH NEXT WEEKEND.

&&

.AVIATION.../06Z TAF ISSUANCE/ 
SNOW OVER NORTHERN MN WILL SHIFT SOUTH INTO THE AREA OVERNIGHT AND
MONDAY AS THE LOW OF RECENT INTEREST CONTINUES TO ROTATE OVER LAKE
SUPERIOR. IFR CIGS WILL PREVAIL TONIGHT AND MONDAY...AND IFR VSBYS
WILL ACCOMPANY THE SNOW. THE OTHER CONCERN CONTINUES TO REVOLVE
AROUND WINDS. SUSTAINED WINDS IN THE MID 20S /KNOTS/ CONTINUE TO
LOOK PROBABLE ACROSS THE MN COUNTIES ON MONDAY...PER BUFKIT
SOUNDINGS. SREF PROBS OF 20-25 PERCENT FOR WINDS GREATER THAN 34
KNOTS ARE DEPICTED ACROSS THE WESTERN HALF OF MN...INCLUDING
KAXN/KSTC/KRWF. BLOWING SNOW WILL ALSO BE A CONCERN ON MONDAY
AFTERNOON AND NIGHT IN AREAS THAT RECEIVE NEW SNOW...SO HAVE
INCLUDED BLSN IN THE AFTERNOON/EVE PORTIONS OF THE TAFS. THE DRY
PUNCH OF AIR IN THE WAKE OF THE LOW DOES NOT REALLY ARRIVE UNTIL
AFTER 06Z TUESDAY...SO LOW CIGS HAVE BEEN RETAINED THROUGH THE TAF PERIOD. 

KMSP...CIGS WILL FLIRT BETWEEN THE MVFR/IFR CATEGORIES EARLY IN THE
PERIOD...BUT BECOME PREDOMINATELY BELOW 1000 FT ON MONDAY. SNOW IS
EXPECTED TO IMPACT KMSP MOSTLY BETWEEN 14Z AND 22Z...WITH LOW END
IFR VSBYS POSSIBLE. STILL CANNOT RULE OUT A BRIEF DIP BELOW 1SM
WITH SNOW ON MONDAY AFTERNOON. WINDS WILL BE SUSTAINED AROUND 20
KNOTS BY MID MORNING MONDAY...WITH GUSTS INTO THE LOW 30S POSSIBLE
THROUGH THE AFTERNOON.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WIND ADVISORY UNTIL MIDNIGHT CST MONDAY NIGHT FOR BLUE EARTH-
     BROWN-CHIPPEWA-FARIBAULT-KANDIYOHI-LAC QUI PARLE-MARTIN-
     MCLEOD-MEEKER-NICOLLET-REDWOOD-RENVILLE-SIBLEY-SWIFT-
     WATONWAN-YELLOW MEDICINE.

     WINTER WEATHER ADVISORY UNTIL 6 PM CST MONDAY FOR DOUGLAS-POPE-
     STEARNS-STEVENS-TODD.

WI...NONE.
&&

$$

LS/MTF