FXUS63 KMPX 070600
AFDMPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1200 AM CST MON DEC 7 2009
.UPDATE...
06Z AVIATION DISCUSSION ADDED BELOW.
&&
.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 PRONOUNCED 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.../06Z TAF ISSUANCE/
EXTENSIVE MVFR CIGS EXIST ACROSS ALL BUT SC AND EC MN AND WC WI
TONIGHT THANKS TO BROAD UPPER TROUGH...WITH EMBEDDED SHORTWAVES...
MOVING ACROSS THE REGION. SEEING A WEAK SFC LOW SKIRT ACROSS MO IN
RESPONSE TO THIS...WITH A STATIONARY FRONT EXTENDING TO THE NE
INTO SE WIS. MOST SNOW AND BEST MOISTURE HAS STAYED ALONG AND NW OF
THIS BNDRY...AND BASED ON LATEST RUC/LOCAL WRF RUNS...EXPECT THIS
TREND TO CONTINUE WITH NO MORE THAN FLURRIES AT ALL TAF SITES WITH
NO RESTRICTIONS. SIGNIFICANT SWATH OF DRY AIR ACROSS ERN MN AND WC WI
HAS KEPT MSP/RNH/EAU VFR FOR QUITE SOME TIME...AND EXPECT THIS TO
CONTINUE FOR THE FIRST FEW HOURS OF THE TAF AT LEAST. GFS RH
PROFILE AT MSP HOLDS OFF MVFR CIGS UNTIL 12Z...THOUGH WITH NW METRO
AIRPORTS ALREADY MVFR...CONTINUED TREND OF BRINGING THEM IN A
LITTLE EARLIER. NAM/GFS STILL INDICATING SOME IMPROVING CIG
HEIGHTS FOR THE AFTERNOON AT MSP/RNH/EAU...AS THIS MORNINGS PRECIP
NEVER REALLY MOISTENS THE ATMO. AT THE OTHER THREE TERMINALS
HOWEVER...GFS KEEPS MOISTURE LOOKED IN IN THE 015 TO 020 LEVEL AND
NOT ANTICIPATING ANY IMPROVEMENTS AT AXN/STC/RWF THIS TAF PERIOD.
ANY SIGNIFICANT RESTRICTIONS WITH THE NEXT SYSTEM LOOK TO HOLD OFF
AT ALL TERMINALS UNTIL AFTER 12Z TUESDAY. FOR WINDS...EXPECT WINDS
UNDER 10 KTS TO CONTINUE OUT OF SOME NRLY DIRECTION DURING THE
PERIOD. BUT...MODELS BRING SFC RIDGE ACROSS THE AREA TOMORROW
NIGHT...WHICH MAY LEAD TO A BRIEF PERIOD OF LIGHT AND VARIABLE
WINDS BEFORE THEY BEGIN TURNING THE THE EAST IN RESPONSE TO
DEEPENING LOW OVER OK.
&&
.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.
&&
$$
TDK/MPG
