649
FXUS63 KMPX 091208
AFDMPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
608 AM CST TUE FEB 9 2010
DISCUSSION
WINTER STORM WARNING EXPIRED FOR PORTIONS OF CENTRAL MN. WL
CONTINUE WARNING UNTIL NOON FOR S MN. ANOTHER 1-2 INCHES OF SNOW
POSSIBLE SC MN THIS MORNING. SURFACE PRESSURE GRADIENT ALSO
CONTINUES TO TIGHTEN IN S MN SO XCPT AREAS OF DRIFTING SNOW DUE TO
THE FLUFFY NATURE OF SNOW.
AVIATION
/12Z TAF ISSUANCE/
WELL DEFINED UPR LOW ON THE IA/MO BRDR NR KLWD (LAMONI)CONTG TO DROP
SE. UVV WELL N OF LOW CONTG ACRS INTO SE MN AND TWRD KEAU. XPCT
VSBYS TO OCNL DROP INTO IFR RANGE AT MSP AND EAU THRU MUCH OF MRNG
WITH OCNL MVFR CIGS AT RWF/MSP/EAU. CONTD IMPRVMT DRNG AFTN AS LOW
MVS INTO IL. SFC PRES GRAD HAS BEEN TIGHTENING LAST SVRL HRS WITH
GUSTS ARND 20 KTS AT RWF. SHUD SEE SOME GUSTS ARND 20 KTS ALSO AT
EAU/MSP BFR 15Z. SFC HI PRES RIDGE BLD INTO W MN THIS EVE AND INTO
CNTL MN BY 12Z. THIS WILL CAUSE RMNG CLDS TO BCM SCT. HOWEVER...EAU
AND RNH MAY SEE MVFR CIGS OFF LK SUPERIOR.
KMSP...XPCT GRNY MVFR VSBYS THRU MRNG IN -SN...BUT CIGS RMNG MAINLY
VFR. SFC WNDS SHUD CONT TO INCRS NEXT FEW HRS TO ARND 15KTS FROM NNE
AS PRES GRAD TIGHTENS. MAINLY VFR DRNG AFTN WITH FEW PRDS -SN...BUT
VSBYS ABV 5SM.
PREV DISCUSSION
/ISSUED 345 AM CST TUE FEB 9 2010/
DEPARTING WINTER STORM LEAVES LINGERING CHALLENGES OF SNOWFALL
TODAY...ALONG WITH BLOWING SNOW POTENTIAL. OTHERWISE TEMPERATURES
WILL BECOME THE GREATER CHALLENGE THROUGH MIDWEEK.
SYSTEM PHASING IS ONGOING ACROSS THE MID-MISSISSIPPI VALLEY BASED
ON THE EARLY MORNING GOES WATER VAPOR LOOP. A DEEP MOISTURE FETCH
AHEAD OF THIS EXTENDS FROM THE GULF NORTHWARD TO THE GREAT LAKES
AND THEN BACK WEST INTO OUR REGION. THIS HAS TROWAL FEATURES WITH
STRONG WESTWARD ADIABATIC ASCENT AND SATURATION IN THE MID-
LEVELS. HAVE FOLLOWED THE 275K SFCS FROM THE NAM AND RUC WHICH
BASICALLY KEEP ASCENT AND SNOW AREAWIDE THIS MORNING AND TAPERING
FROM WEST TO EAST THIS AFTERNOON. MUCH OF THIS SNOW BY AFTERNOON
WILL BE LIGHT. AN ADDITIONAL ONE TO TWO INCHES IS EXPECTED ACROSS
SOUTHEAST MN TO NEAR DURAND AND EAU CLAIRE WI. THE PRESSURE
GRADIENT REMAINS THE SAME OVER THE AREA AS SYSTEM DEPARTURE IS
OFFSET BY ITS DEEPENING. WIND SPEEDS SHOULD REMAIN FAIRLY STEADY
WITHIN THIS GRADIENT...AT 10 TO 20 MPH MOST PLACES WITH THE
HIGHEST IN SOUTH CENTRAL AND SOUTHEAST MN. BLOWING AND DRIFTING
SNOW PROBLEMS HAVE BEEN MINOR REPORTED BY LAW ENFORCEMENT. BUT
GIVEN THE LIGHT WATER CONTENT WITHIN THE FRESH SNOW COVER AND
WITH THE CONTINUED ACCUMULATING SNOWFALL THROUGH THIS
MORNING...BELIEVE IT PRUDENT TO CONTINUE WARNING AND ADVISORY
THROUGH NOON JUST AS ORIGINALLY PLANNED.
TEMPERATURES TODAY ARE A CHALLENGE WITH SPOKES OF WARM AND COLD
AIR WRAPPED AROUND THIS SYSTEM. WE ARE UNDER A WARM TONGUE EARLY
THIS MORNING AND BELIEVE THAT THIS AFTERNOONS COLD AIR ADVECTION
WILL BE FAIRLY WEAK...AND OFFSET BY SOME SUN IN WESTERN MN...SO
GENERALLY HAVE STEADY TEMPERATURES WITHIN THE HOURLY GRIDS.
TONIGHT WILL BE LINGERING LIGHT SNOW IN WRN WI EVENTUALLY END.
CLEARING SHOULD BE QUICK TO SPREAD INTO WRN MN BUT MORE GRADUAL
ELSEWHERE GIVEN FORECASTED DRY AIR ADVECTION AND MID-LEVEL
SUPPRESSION. THE SFC RIDGE IS FORECAST TO BE NEAR THE DAKOTAS AND
MN BORDER BY 12Z WED WITH SURFACE WINDS DROPPING TO CALM. GIVEN
THE FRESH SNOW COVER...SOME WRN MN COMMUNITIES SHOULD SEE AROUND
10 BELOW. NEAR OR BELOW ZERO VALUES SHOULD BE SEEN IN THE CITIES
TOO...BARRING LINGERING STRATOCU OVERNIGHT. THE RANGE FOR ERROR
THOUGH IS ADMITTEDLY LARGE GIVEN THE FACTORS.
THE RIDGE WILL MOVE OVER THE AREA WED AND WED NIGHT. WED NIGHT
AGAIN OFFERS A CHILLY NIGHT...THIS TIME OVER ERN MN INTO WRN WI.
HAVE LOWERED TEMPS TOWARDS COOLER GUIDANCE THERE AND ADAPTED A
FRESH SNOW COVER DECREASE AS WELL...ESPECIALLY FROM GLENWOOD TO
THE SOUTHWEST METRO TOWARDS OWATONNA. THESE AREAS SHOULD GET TO 10
BELOW OR LOWER IF LITTLE TO NO CIRRUS.
THE UPPER LEVEL NW FLOW WILL BECOME MORE DISTURBED THU NIGHT INTO
THE WEEKEND AS A PAIR OF SHORTWAVES DROP SOUTHWARD. THE SECOND ONE
IS EXPECTED TO BE DEEPER AND GUIDANCE HAS TRENDED WITH MORE OF AN
IMPACT FROM THAT ONE DURING SATURDAY. BOTH THE 00Z ECMWF AND GFS
HAVE A CLOSED 500MB LOW TAKING A SSE PATH ON SATURDAY...SIMILAR TO
THIS PAST ONE JUST MOVING MUCH QUICKER. CONTINUE THE SMALL SNOW
CHANCES FOR FRI AND HAVE INTRODUCED A CHANCE NOW FOR SATURDAY. DAY
SHIFT MAY NEED TO INCREASE THIS IF A MORE CONSISTENT SIGNAL IS
SEEN IN GUIDANCE.
MPX WATCHES/WARNINGS/ADVISORIES
MN...WINTER STORM WARNING UNTIL NOON CST TODAY FOR BLUE EARTH-BROWN-
CARVER-DAKOTA-FARIBAULT-FREEBORN-GOODHUE-HENNEPIN-LAC QUI
PARLE-LE SUEUR-MARTIN-MCLEOD-NICOLLET-RAMSEY-REDWOOD-
RENVILLE-RICE-SCOTT-SIBLEY-STEELE-WASECA-WATONWAN-YELLOW
MEDICINE.
WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR WASHINGTON.
WI...WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR PEPIN-PIERCE-
ST. CROIX.
MTF/BAP
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page