FXUS63 KMPX 020748
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
148 AM CST WED DEC 2 2009

.DISCUSSION...

WINTER CONTINUES TO ARRIVE ON NORTHWEST WINDS AND WILL INTO
TODAY AND TONIGHT...WITH COLDER TEMPERATURES AND OCCASIONAL
FLURRIES/SNOW SHOWERS THE NEXT FEW DAYS OFFERING THE CHALLENGES TO
THE FORECAST.

NORTHERN HEMISPHERIC WV LOOP SHOWING ROSSBY WAVE TROUGH SETTING
UP OVER NORTH AMERICA...WITH COLD AIR/LOW THICKNESSES FINALLY
BEGINNING TO REDISTRIBUTE INTO THE WRN HEMISPHERE. WITHIN CURRENT
SYNOPTIC TROUGH DIGGING INTO THE CENTRAL U.S. THE COLDEST 500MB
TEMPS WERE SEEN AT KCYD NORTH OF LAKE WINNIPEG LAST EVE...WITH A
ROBUST -38C. THIS COLD POCKET WILL SINK SOUTH INTO OUR AREA AND
MODIFY SOME AS IT DOES. THIS AREA AND ITS ENHANCED LAPSE RATES AND 
VORT MAXS WILL OFFER THE BEST CHANCE FOR SNOW SHOWERS AND FLURRIES
THIS AFTN IN WEST CTRL MN AND TONIGHT INTO THU ACROSS THE REST OF
THE CWA. THE NAM AND GFS MODELS ARE IN GOOD AGREEMENT WITH THIS
WITH TIMING CONFIDENCE OF THE SREF. HAVE USED AS FORECAST TOOLS
THE AFOREMENTIONED MID-LEVEL COLD POCKET...LOW LEVEL LAPSE
RATES...AND 850-700MB VORT LAYERS. ALL IN ALL...GOOD AGREEMENT
WITH THE PREVIOUS FORECAST WITH JUST SOME INCREMENTAL INCREASES IN
POPS IN THE NEXT 12-36 HOURS.

FOR TODAY...WHILE A FEW HOLES MAY EXIST THIS MORNING...AFTN SFC
LAPSE RATES AND ASSOCIATED CU RULE FROM THE NAM MODEL FAVOR OVC
STRATOCU BY AFTN. COLD AIR ADVECTION CONTINUES IN THE LOW LAYERS
WITH VERY MODEST HEATING TODAY...SO HAVE ONLY 3 TO 6 DEGREE
TEMPERATURE CLIMBS. SOME SNOW SHOWERS SHOULD BE SEEN IN NW TO SE
BANDS ACROSS WEST CTRL MN BY AFTN. THE 4KM NMMWRF PAINTS THIS
PICTURE...WHICH AGREE WELL WITH VORT PLACEMENT ON THE NAM/GFS.

WITH MID-LEVEL THERMAL TROUGH DIRECTLY OVER THE AREA TONIGHT AND
THU...WENT WITH PRIMARILY SCT WORDING FOR SNOW SHOWERS. ACCUMS
SHOULD BE NOTHING OR MINOR WHERE THEY OCCUR AS LITTLE IN THE WAY OF
BROAD OMEGA IS PAINTED . ITS POSSIBLE THAT 0.5 TO 1 INCH MAY FALL
IN A FEW PLACES IN WEST CTRL OR CTRL MN. FOR TEMPS HAVE BUMPED UP
MINS A BIT WITH SO ROBUST OF CLOUD COVER MINIMIZING THE TEMP
RANGE...BUT OVERALL THE DAILY OSCILLATION KEEPS FALLING THROUGH
FRI. SO BY FRI MORNING AND SAT MORNING...LOWS IN THE TEENS WITH
ISOLATED SINGLE DIGITS UNDER DEVELOPING CLOUD HOLES ARE EXPECTED.

WHEN THE CLOUDS BREAK UP STILL REMAINS SOMEWHAT UNCERTAIN...WITH
THE BEST ESTIMATE ON SAT OR SAT NIGHT AS LONG WAVE TROUGH CENTER 
WORKS A BIT FURTHER NORTH IN ERN CANADA. TEMPS SHOULD BE NEAR
NORMAL THIS WEEKEND...WITH ANY PRECIP FORCING VERY LIGHT. RIGHT
NOW CONTINUE WITH NO MENTION. FORECAST CONFIDENCE FOR THE FIRST
HALF OF NEXT WEEK DROPS QUICKLY. PACIFIC NW TROUGH EXPECTED TO
SHIFT EASTWARD IN PIECES ON THE MODEL GUIDANCE BUT TIMING AND
DEPTH OF WAVES VARY SIGNIFICANTLY. WITH JET AND BAROCLINIC ZONE
FOCUSED TO OUR SOUTH...TEMPS FOR NEXT WEEK CERTAINLY LOOK BELOW
NORMAL. WILL HAVE TO MAINTAIN PATIENCE FOR SNOW CHANCES.

&&

.AVIATION.../06Z TAF ISSUANCE/ 

MAIN AVIATION CONCERN DEALS WITH CEILINGS AND HOW THEY WILL
FLUCTUATE BETWEEN LOW END MVFR (1200-1500') TO HIGH END MVFR OR
LOW END VFR (2500-3500') DURING THE NEXT 24/30 HRS. ALTHOUGH THERE
REMAINS SOME VFR CEILINGS ACROSS PORTIONS OF THE TAF CWA LATE THIS 
EVENING...OVERALL THE GENERAL TREND IS TO HAVE CEILINGS LOWER
OVERNIGHT...BUT MODIFY A BIT DURING THE DAYTIME BEFORE DROPPING
AGAIN TOWARD THE EVENING. WINDS WILL REMAIN PERSISTENT FROM THE
W/NW THRU 18Z...THEN BECOME MORE NW/N AFTER THIS TIME PERIOD. IN
ADDITION TO THE CEILINGS...DEEPER MOISTURE WILL BEGIN TO SPREAD
SOUTHEAST ACROSS THE CWA AND ALLOW FOR -SN TO DEVELOP.
HOWEVER...IT SHOULD REMAIN LIGHT ENOUGH FOR VFR VSBY AT THIS TIME.
LATER SHIFTS WILL NEED TO MODIFY VSBY IF A CONCENTRATED AREA OF
-SN BEGINS TO LOWER SFC VSBYS A FEW HRS. ..JLT..

&&

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

$$

MTF/JLT