FXUS63 KMPX 071144
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
544 AM CST MON DEC 7 2009

.DISCUSSION...
WEAK SURFACE TROUGH CENTERED OVER MISSOURI INTO THE GREAT 
LAKES...WILL MOVE EAST AS SURFACE RIDGE OF HIGH PRESSURE BUILDS OVER 
THE UPPER MIDWEST TODAY AND TONIGHT.  LIGHT SNOW..MAINLY SNOW 
FLURRIES IS EXPECTED TO END OVER FAR SOUTH CENTRAL MN (ALONG AND 
SOUTH OF THE INTERSTATE 90 CORRIDOR THIS MORNING.
 
TEMPERATURES WILL STRUGGLE TO REACH INTO THE LOWER 20S IN THE FAR
NORTHERN SECTION OF OUR FORECAST AREA...AND INTO THE MIDDLE 20S IN
THE SOUTH.

IN THE MEDIUM RANGE...MODELS HAVE BEEN CONSISTENT WITH NEXT WEATHER 
PRODUCER WITH THE PLACEMENT OF THE HEAVIER PRECIPITATION AND 
START/END TIMES OF THE SNOW. THE HEAVIEST QPF AND SNOWFALL WILL 
LIKELY OCCUR SOUTH AND EAST OF CWA. INVERTED UPPER LEVEL TROUGH WILL 
SLOWLY MOVE FROM THE PACIFIC NORTHWEST INTO THE CENTRAL ROCKIES BY 
TUESDAY AFTERNOON...BECOME NEGATIVELY TILTED AS IT MOVE THROUGH THE 
UPPER MIDWEST TUESDAY NIGHT AND WEDNESDAY. EXPECT A PROLONG PERIOD 
OF SNOW WITH SNOW BECOMING HEAVY AT TIMES...AS OMEGA FIELDS (FORCING
AND UPWARD VERTICAL MOTION MAX OUT TUESDAY NIGHT ACROSS OUR
FORECAST AREA. WITH THE ARCTIC AIR WELL ENTRENCHED OVER THE
FORECAST AREA...SNOW DEVELOPING IN IDEAL DENDRITIC SNOW GROWTH
AREA OVER SOUTHEAST THIRD OF MN AND PARTS OF WESTERN WISCONSIN.
THE WINTER STORM WATCH SEEN REASONABLE FOR TUESDAY THROUGH
WEDNESDAY. SURFACE PRESSURE GRADIENT IS EXPECTED TO TIGHTEN OVER
THE UPPER MIDWEST. THE LATEST MODEL RUNS ARE INDICATING A MORE
SIGNIFICANT WIND EVENT OVER SOUTH CENTRAL MN. THUS...THE BLIZZARD
WATCH WILL REMAIN IN EFFECT MAINLY FOR THE TIME-FRAME TUESDAY
NIGHT INTO WEDNESDAY AFTERNOON. FINE GRAINS OF SNOW WILL CAUSE
SIGNIFICANT BLOWING AND DRIFTING OF SNOW...THUS PRODUCING NEAR
WHITEOUT CONDITIONS...THEREBY IMPACTING MOTORISTS TRAVELING OVER
SOUTHERN MN.

THE REST OF THE WORK WEEK LOOKS DRY AND COLD.  THE LATEST GFS AND 
ECMWF MODELS WERE SHOWING MORE OF A SPLIT UPPER AIR FLOW ACROSS THE 
UPPER MIDWEST. MOST OF THE WAVE ENERGY ASSOCIATED WITH SHORT WAVES 
AND MINOR IMPULSES WILL STAY NORTH OF CWA AT LEAST THROUGH THE 
WEEKEND. 

&&

.AVIATION.../12Z TAF ISSUANCE/ 

MAIN AVIATION CONCERNS DEAL WITH THE AMOUNT OF LOW LEVEL MOISTURE
BELOW 85H AND IF MVFR CEILINGS WILL REDEVELOP AGAIN ACROSS
MSP/STC/RNH/EAU DURING THE MORNING. CURRENT RH FIELDS BELOW 85H
HAS A DRY POCKET ACROSS EAST CENTRAL MN AND WEST CENTRAL WISCONSIN
WHICH HAS AIDED IN THE BREAK UP OF THE MVFR CEILINGS OVERNIGHT.
HOWEVER...THERE REMAINS ENOUGH MOISTURE IN THIS LAYER TO CONTINUE
SCATTERED CLOUDS AROUND 2000/2500'...BUT KEPT THE CEILINGS IN THE
VFR RANGE AT THIS TIME FOR STC/MSP/RNH/EAU. RWF/AXN REMAIN TOO
CLOSE TO THE MVFR CEILINGS AND MOIST (85H) POCKET TO CONTINUE MVFR
CEILING TRENDS. NO VSBYS PROBLEMS ARE EXPECTED THRU 12Z ON
TUESDAY. WINDS WILL BE GENERALLY FROM THE N/NW UNDER 10 KTS TODAY
...THEN BECOME N/NE TOWARD 12Z TUESDAY. ..JLT..

&&

.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.

&&

$$

JVM/JLT