FXUS63 KMPX 062202
AFDMPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
402 PM CST SUN DEC 6 2009
.DISCUSSION...
AN AREA OF LOW PRESSURE WILL PASS ACROSS THE MIDDLE MISSISSIPPI
VALLEY OVERNIGHT BRINGING A PERIOD OF LIGHT SNOW TO FAR SOUTHERN
AREAS OF MN. NAM/GFS 285K THETA PROGS INDICATE SATURATION AND
ISENTROPIC OMEGA BRUSHING THE SOUTHERN TWO ROWS OF COUNTIES OF THE
MN CWA. HAVE KEPT LIKELY TO CATEGORICAL POPS IN THIS AREA WITH
ABOUT AN INCH OF SNOW ALONG THE INTERSTATE 90 CORRIDOR. THE SYSTEM
WILL BE EXITING THE FA MONDAY MORNING WITH LINGERING LIGHT SNOW IN
THE MORNING FROM ALBERT LEA TO SOUTH OF EAU CLAIRE.
FLURRIES WILL BE COMMON OVERNIGHT AND EARLY MONDAY ACROSS MUCH OF
THE REMAINING CWA AS ARCTIC AIR CONTINUES TO FILTER IN FROM ND. LOW
TEMPERATURES TONIGHT AND HIGHS ON MONDAY REMAIN WELL BELOW NORMAL
WITH READINGS A LITTLE BELOW MAV/MET GUIDANCE. COLDEST LOWS/HIGHS
WILL AGAIN BE ACROSS WESTERN AND CENTRAL MN.
BIG STORM - MODELS HAVE BEEN VERY CONSISTENT WITH PLACEMENT AND
MAJOR INTENSIFICATION OF NEXT SYSTEM TUESDAY NIGHT TO OUR
SOUTHEAST. THE ONLY REAL THING THAT HAS CHANGED IS A GRADUAL
PLACEMENT FARTHER NORTHWEST WITH EACH MODEL RUN. THIS HAS
CONTINUED ON THE 12Z RUN AS WELL. DESPITE 7H LOW TRACKING NEWD
ACROSS SOUTHERN IOWA TOWARD SERN WISC...THERE CONTINUES TO BE A
VERY PRONOUCED INVERTED TROUGH POKING NORTHWESTWARD INTO MN AND
NWRN WISC. AND THE 18Z GFS40 SHOWS A SECONDARY SMALL 7H LOW MOVING
RIGHT ACROSS CENTRAL MN...A TREND THAT THE GFS40 HAS BEEN SHOWING
FOR SEVERAL RUNS. OMEGA FIELDS DEPICT EXCELLENT LIFT ON THE
NORTHWEST SIDE OF THE MAIN 7H LOW...ALONG WITH EXCELLENT
FRONTOGENESIS FROM SW MN INTO NWRN WISC. VERY NICE COUPLED JET
STRUCTURE. ALL THIS WITH A TIGHT THERMAL CONTRACT RIGHT ACROSS
CENTRAL MN TOWARD WRN LAKE SUPERIOR. COULD WELL BE SOME LOCALIZED
SNOWFALL TOTALS IN THE DOUBLE DIGITS IN BANDED SNOW. TEMPS AT THE
-15C LEVEL ARE JUST AT THE UPPER THRESHOLD FOR GOOD DENDRITIC SNOW
CRYSTAL FORMATION. COBB RATIONS ON THE ORDER OF 15-16 TO 1. MIXING
RATIOS 2-3 G/KG. WITH A QPF AROUND 0.4 TO 0.5 INCH TUE AFTERNOON
INTO WED MIDDAY...LOOKS LIKE A BROAD 6 TO 8 INCHES WILL BE OVER A
GOOD SHARE OF THE AREA...AGAIN WITH LOCALIZED HIGHER AMOUNTS.
THE NEXT CONCERN IS WIND. WITH SUCH STRONG INTENSIFICATION AND
INCOMING ARCTIC AIR...STAGE IS SET FOR SOME STRONG WIND ON THE
BACKSIDE OF THE LOW. ADIABATIC PROFILES BY WEDNESDAY MORNING IN
THE LOWEST FEW THOUSAND FEET WITH WINDS JUST OFF THE SURFACE
AROUND 35 KNOTS. EXCELLENT DOWNWARD TRANSFER OF MOMENTUM. EXPECT
SFC WINDS SHOULD BE AROUND 35 TO 40 MPH. PER BUFKIT...WINDS WILL NOT
REV UP UNTIL LATE TUESDAY NIGHT BUT RATHER THAN SWITCH HIGHLIGHTS
IN MID STREAM... WILL GO WITH BLIZZARD WATCH RIGHT OFF THE BAT IN
SC MN...AND WINTER STORM WATCH FOR THE REST OF SW INTO EC MN AND
WISC.
COLDER AIR WILL DROP IN BEHIND THE SYSTEM. DEPENDING ON CLOUD
COVER...SHOULD BE ABLE TO GET SOME BELOW ZERO READINGS OVER THE
FRESH SNOW COVER. THIS WILL KEEP TEMPERATURE BELOW NORMAL THEN
THROUGH NEXT WEEKEND.
THE TUE/WED STORM WILL MOVE EAST AND ANOTHER LARGE UPPER LOW IS
SET TO FOLLOW THIS WEEKEND...AND MODELS HAD BEEN INDICATING QUIET
WEATHER THROUGH THE WEEKEND. BUT NEW 12Z ECMWF BRINGS NEXT UPPER
LOW FARTHER SOUTH. WILL WAIT TO SEE IF THIS SOLUTION HOLDS UP. IF
IT DOES...ANOTHER ARCTIC FRONT AND LIGHT SNOW MAY MOVE IN. FOR NOW
HAVE INDICATED QUIET WEATHER THIS NEXT WEEKEND.
&&
.AVIATION.../18Z TAF ISSUANCE/
ARCTIC HIGH PRESSURE STRETCHES FROM ND TO WI AND WILL MOVE LITTLE
THROUGH THE FORECAST PERIOD AS A WEAK AREA OF LOW PRESSURE PASSES
SOUTH OF THE REGION OVERNIGHT. MVFR STRATUS COVERS THE NORTHERN
TWO-THIRDS OF MN WITH CLR-SCT CONDITIONS TO THE SOUTH AND EAST.
LITTLE CHANGE EXPECTED WITH THE STRATUS TRAPPED UNDER THE
RIDGE...WHILE SLOW FILLING IN THE LOW CLOUDS OCCURS ACROSS
SOUTHERN MN THIS AFTERNOON AND ACROSS WEST CENTRAL WI THIS
EVENING. FLURRIES WILL BE COMMON WITH THE STRATUS WITH
VISIBILITIES FROM 3 TO 5 MILES FROM TIME TO TIME. NORTH WINDS IN
THE 6 TO 10 KNOT RANGE TONIGHT BACKING NW ON MONDAY.
KAXN...CEILINGS IN THE 010-020 FOOT RANGE THROUGH THE PERIOD WITH
OCCASIONAL FLURRIES PRODUCING 3-5 MILE VISIBILITIES.
KSTC...CEILINGS IN THE 020-025 FOOT RANGE THIS AFTERNOON LOWERING
INTO THE 010-020 FOOT RANGE TONIGHT AND CONTINUING MONDAY MORNING.
OCCASIONAL FLURRIES PRODUCING 3-5 MILE VISIBILITIES.
KRWF...CEILINGS IN THE 015-02O FOOT RANGE DEVELOPING EARLY THIS
AFTERNOON AND THEN CONTINUING THROUGH THE REST OF THE TAF PERIOD.
OCCASIONAL FLURRIES OCCURRING WITH THE CEILINGS PRODUCING 3-5 MILE
VISIBILITIES.
KMSP...BKN CONDITIONS AROUND 025 DEVELOPING EARLY THIS AFTERNOON
ALONG WITH A FEW FLURRIES. SOME INDICATIONS THAT THE CEILING MAY
SCT BY EVENING WITH THE LOSS OF HEATING. HOWEVER...AS THE EVENING
PROGRESSES THE STRATUS TO THE NORTH AND WEST PROGGED TO FILL IN
WITH CEILINGS IN THE 015-020 RANGE BY 07/06Z AND NEAR 010 BY
DAYBREAK MONDAY. OCCASIONAL MVFR VISIBILITIES IN FLURRIES
OVERNIGHT AND MONDAY MORNING AS WELL.
KRNH...VFR CONDITIONS THIS AFTERNOON WITH BKN MVFR CEILINGS
AROUND 020 FORECAST TO DEVELOP THIS EVENING AND CONTINUE
OVERNIGHT. OCCASIONAL MVFR VISIBILITIES IN FLURRIES
OVERNIGHT AND MONDAY MORNING WILL ACCOMPANY THE CEILINGS.
KEAU...VFR CONDITIONS THIS AFTERNOON AND EARLY TONIGHT. BKN MVFR
CEILINGS AROUND 020 FORECAST TO DEVELOP DURING THE 07/06Z-09Z
TIME FRAME AND CONTINUING THROUGH THE END OF THE TAF PERIOD.
OCCASIONAL MVFR VISIBILITIES IN FLURRIES EXPECTED MONDAY MORNING.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WINTER STORM WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY
EVENING FOR ANOKA-BROWN-CARVER-CHISAGO-DAKOTA-GOODHUE-
HENNEPIN-ISANTI-KANABEC-LE SUEUR-MCLEOD-MEEKER-NICOLLET-
RAMSEY-REDWOOD-RENVILLE-RICE-SCOTT-SHERBURNE-SIBLEY-
WASHINGTON-WRIGHT.
BLIZZARD WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY EVENING
FOR BLUE EARTH-FARIBAULT-FREEBORN-MARTIN-STEELE-WASECA-
WATONWAN.
WI...WINTER STORM WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY
EVENING FOR BARRON-CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE-
POLK-RUSK-ST. CROIX.
&&
$$
RAH/TDK/RAH
