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