FXUS63 KMPX 041515
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
915 AM CST FRI DEC 4 2009

.UPDATE...

RADAR AND SFC OB TRENDS SHOW A LARGE AREA OF SNOW SHOWERS ACROSS
THE NORTHEASTERN TWO-THIRDS OF THE CWA THIS MORNING. SATELLITE
SHOWS COLD UPPER VORTEX ROTATING OVER ONTARIO AND THE UPPER GREAT
LAKES WITH A SERIES OF WEAK WAVES ROTATING AROUND IT. CONTINUED
Q-VECTOR CONVERGENCE AND DEEP LAYER OF MOISTURE ASSOCIATED WITH A
PASSING VORT MAX SUGGEST THAT SNOW SHOWERS WILL CONTINUE INTO THE
AFTERNOON WITH THE VERY COLD AIR DOING AN EFFICIENT JOB OF
WRINGING OUT THE MOISTURE. ADDITIONAL FLUFFY ACCUMULATIONS UP TO A
HALF OR ONE INCH ARE EXPECTED ALONG THE INTERSTATE 94 CORRIDOR
WITH LESSOR AMOUNTS AND LESSER SNOW SHOWER COVERAGE TO THE SOUTH
AND WEST OF THE INTERSTATE. THE BULK OF THE ACTIVITY WILL PIVOT EAST
WITH TIME THIS AFTERNOON BUT SCATTERED FLURRIES AND ISOLATED SNOW
SHOWERS WILL CONTINUE ACROSS THE MN CWA ONCE THE MORE WIDESPREAD
ACTIVITY IS MORE FOCUSED OVER WEST CENT WI.  ..MDB..

&&

.AVIATION.../12Z TAF ISSUANCE/ 
MVFR FLYING CONDITIONS WILL CONTINUE THROUGHOUT THE DAY. CEILING 
HEIGHTS WILL VARY FROM 2000-3500 FEET AGL WITH VISIBILITIES 3-6 
MILES IN SNOW. CONDS WILL IMPROVE FROM WEST TO EAST TONIGHT AND 
SATURDAY TO VFR CONDITIONS...CLOUDS OR CEILINGS AT OR ABOVE 5 
THOUSAND FEET AGL.  SFC WINDS WILL BE WEST AT 5 TO 15 KNOTS. 

&&

.PREV DISCUSSION...
/ISSUED 345 AM CST FRI DEC 4 2009/

FORECAST CONCERN NEAR TERM IS THE CONTINUING THREAT OF SNOW
SHOWERS OVER MAINLY THE NORTHERN PORTION OF THE CWA DURING THE
DAY. MODELS CONTINUE TO TREND WHAT APPEARS TO BE VIGOROUS VORT
MAXIMA ROTATING VCNTY OF LAKE WINNIPEG THIS MORNING. TREND OF THE
NAM_WRF WAS TO INTENSIFY IT A BIT AS IT MOVES SOUTH SOUTHEAST
DURING THE AFTERNOON/EVENING. SOME DECENT LIFT/Q VECTOR
CONVERGENCE MOVES OVER THE NORTHEAST CWA THIS AFTERNOON/EVENING.
THIS IS ENOUGH FOR CHANCE POPS OVER THE NORTHERN AREA FOR MORE
SNOW SHOWERS TODAY. CLOUDS DID BREAK OPEN OVER THE SOUTHWEST IN
THE WAKE/SUBSIDENCE OF THE PREVIOUS SHORT WAVE. THIS PROVIDED NICE
TEMP DROP IN LIGHTLY SNOW COVERED REGION OF THE SOUTHWEST. SHOULD
SEE CLOUDS MOVE BACK IN EARLY THIS MORNING AS NEXT WAVE
APPROACHES. SOME WEAK CAA CONTINUES INTO THIS MORNING AND WITH
EXPECTED CLOUDS...LITTLE RISE IN TEMPERATURES EXPECTED. WENT WITH
A COLDER NAM GUIDANCE TEMPERATURES CONSIDERING TRAJECTORY OF
AIRMASS FROM YESTERDAY.

SYSTEM EXITS TO THE EAST OF THE AREA OVERNIGHT. SHOULD SEE SOME
CLEARING OVER THE WESTERN AND CENTRAL CWA DURING THE NIGHT. CLOUDS
MAY HANG INTO WC WI THROUGH THE NIGHT AS SFC RDG BUILDS INTO THE
WESTERN CWA. UNCLEAR HOW MUCH CLOUD COVER WILL BE AROUND SAT AND
SUNDAY AS TROUGH SHEARS OFF TO THE EAST. TEMPERATURES WILL BE
DE PENDANT OF CLOUD COVER INTO SUNDAY...SO WENT CLOSE TOM MAV
NUMBERS FOR NOW. MODELS DIVERGE SOMEWHAT ON HANDLING OF NEXT SHORT
WAVE TROUGH FOR SUN NIGHT INTO MONDAY. GFS HOLDS THE WAVE A BIT
FARTHER SOUTH THAN PREVIOUS RUNS...WITH THE COLD SFC HIGH WINNING
OUT ACROSS THE AREA. THE 00Z NAM_WRF AND 00Z ECMWF CONTINUE TREND
OF CLIPPING THE FAR SOUTHERN CWA WITH THIS SYSTEM. WILL TRIM POPS
A BIT TO THE NORTH BUT CONTINUE THE CHANCE POPS OVER THE FAR
SOUTHERN CWA. 

LONGER TERM...MODELS HAVE BEEN TRENDING TOWARD DEVELOPMENT OF
SIGNIFICANT LONG WAVE TROUGH OVER THE NATIONS MIDSECTION TOWARD
MIDWEEK. 00Z RUNS CONTINUE THE TREND OF SIGNIFICANT CYCLOGENESIS
NEAR THE CO/OK PANHANDLE REGION LATE TUE AND LIFTING NORTHEAST TO 
SOUTHERN LK MICHIGAN REGION BY WED MORNING. THIS TRACK WOULD
AFFECT MAINLY OUR SOUTHERN CWA AS THE LOW TRACKS SOUTH AND EAST.
THE HEAVIER SNOWS WOULD CLIP OUR SOUTHERN CWA WITH THE HEAVIEST SNOW
BAND OVER IOWA AND WI. THIS COULD BE OUR FIRST SIGNIFICANT STORM
OF THE SEASON AND WILL HIGHLIGHT THIS THREAT IN THE HWO.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&

$$

MDB/JVM/DWE