FXUS63 KFGF 222139
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
339 PM CST TUE DEC 22 2009

.SHORT TERM...CHALLENGE WILL BE WINTER STORM POTENTIAL. 12Z MODELS
INITIALIZED WITH MINIMAL ERRORS. CONFIDENCE IS DEFINITELY
INCREASING WITH THE STRENGTH AND TRACK OF THIS SYSTEM. ECMWF AND
GFS REMAIN CONSISTENT...TRENDING SLOWER AND STRONGER. NAM IS AN
OUTLIER WITH A MUCH WEAKER SOLUTION. GEM APPEARS TO KEEP TRENDING
TOWARD THE ECMWF/GFS SOLUTION EACH MODEL RUN. AS PER PMDHMD...WILL
FOLLOW ECMWF/GFS FOR DETAILS. 

THROUGH WED AFTERNOON...LOW-LEVEL EASTERLY FLOW FROM DRY SOURCE
REGION SHOULD KEEP THE FA MOSTLY DRY. 

THIS UPCOMING SYSTEM IS QUITE COMPLEX...WITH ONE SHORTWAVE
EJECTING INTO THE CENTRAL PLAINS ON WEDNESDAY...AND THEN ANOTHER
SHORTWAVE DIVING SOUTH ACROSS THE ROCKIES AND MERGING INTO THIS
SYSTEM. THESE COMPLEX INTERACTIONS SOMETIMES ARE NOT HANDLED WELL
BY MODELS THIS FAR OUT. ANYWAY...A STORM IS LIKELY WITH THE MAIN
QUESTION FOR THIS AREA BEING SNOWFALL AMOUNTS AND THEN WIND
POTENTIAL ON FRIDAY. BEST SNOW POTENTIAL WILL BE WITH A WAVE ON
THURSDAY...AND THEN A DEFORMATION ZONE SETTING UP ON FRIDAY. GIVEN
THE SLOW NATURE OF THIS SYSTEM AND AVAILABLE MOISTURE...SIGNIFICANT
SNOW ACCUMULATION APPEARS LIKELY. WITH THE 12Z MODELS TRENDING
SLOWER/STRONGER...EXPECTED SNOWFALL TOTALS THROUGH FRIDAY HAVE
INCREASED SLIGHTLY. SEE CURRENT WX STORY OR TOP NEWS FOR THESE
EXPECTED POTENTIAL TOTALS. AGAIN...THESE TOTALS ARE OVER A 2-3
DAY PERIOD. THERE IS MODEL CONSENSUS (GFS/ECMWF/SREF) FOR
1.00-1.25 INCH QPF VALUES ACROSS THE SOUTHERN FA...AND 0.50 TO
1.00 INCH VALUES ACROSS THE NORTHERN FA. NEAR CLIMATOLOGY SNOW
RATIOS EXPECTED (12:1-14:1) GIVEN EXPECTED AIRMASS.

WIND APPEARS TO BECOME AN ISSUE TOWARD FRIDAY MORNING AND INTO
FRIDAY (FRIDAY NIGHT). DUE NORTH WINDS WITH ADIABATIC LAYER TO
925MB WITH ABOUT 30-35KNTS (35-40KNTS ACROSS THE W FA WITH THE
STRONGEST ECMWF SOLUTION) AVAILABLE TO MIX. HOWEVER...NO STRONG
COLD AIR ADVECTION OR PRESSURE RISE MAXIMUM ANTICIPATED. THIS
SHOULD BE A GRADIENT WIND EVENT...KEEPING WINDS BELOW 30 MPH. AT
THIS TIME THINKING 20-30 MPH ALONG AND WEST OF THE VALLEY...WHICH
WILL CAUSE BLOWING SNOW PROBLEMS. ONE THING TO KEEP IN MIND
THROUGH THE UPCOMING DAYS WILL BE THE VALLEY COMPONENT WITH THE
NORTHERLY WINDS...WHICH MAY INCREASE THESE EXPECTED SPEEDS A BIT.
A TRUE BLIZZARD REMAINS A LOW POSSIBILITY...BUT STILL POSSIBLE
(ESPECIALLY IF THE TREND TOWARD A STRONGER SYSTEM CONTINUES).

WILL KEEP THE WINTER STORM WATCH IN EFFECT. STILL A BIT EARLY TO
UPGRADE TO A WARNING GIVEN THE COMPLEXITY OF THIS SYSTEM...EVEN
THOUGH CONFIDENCE IS INCREASING. THE WINTER WX HAZARD IMPACTS WILL
NOT BE UNTIL THURSDAY ACROSS MUCH OF THIS FA...SO A WATCH IS
STILL APPROPRIATE.

.LONG TERM (SAT-TUE)...THE BEGINNING OF THE LONG TERM PERIOD
SHOULD BRING THE CHRISTMAS WINTER STORM TO AN END. HOWEVER...ALL
LONG TERM MODELS INDICATE A SLIGHTLY SLOWER AND MORE WESTERN TRACK
THAN PREVIOUS RUNS. THIS MEANS THE CHANCE FOR PCPN COULD LINGER
ACROSS THE AREA LONGER THAN PREVIOUSLY FORECAST. THEREFORE...POPS
WERE EXTENDED TO INCLUDE THE EARLY SAT TIME FRAME. THE CHANCE FOR
ANY LIGHT PCPN OVER THE WEEKEND WILL NEED TO BE WATCHED AS THE
MODELS GET A BETTER HANDLE ON THE EXACT STORM TRACK AND HOLIDAY
TRAVELERS BEGIN TO HEAD HOME. STRONG NORTH WINDS SHOULD FINALLY
DIMINISH THROUGHOUT THE DAY SAT REDUCING THE POTENTIAL FOR BLOWING
AND DRIFTING SNOW.

EARLY NEXT WEEK SHOULD BE DRY AS A WEAK HIGH PRESSURE SYSTEM 
ATTEMPTS TO BUILD INTO THE REGION FROM THE WEST. TEMPERATURES SHOULD 
BE ONLY SLIGHTLY BELOW NORMAL THROUGHOUT THE PERIOD.

&&

.AVIATION...CONDITIONS WILL BE VFR FOR THE REMAINDER OF THE
AFTERNOON WITH EMBEDDED POCKETS OF MVFR CIGS.
HOWEVER...PREDOMINANT MVFR CIGS WILL MOVE INTO THE AREA OVERNIGHT.
WINDS WILL FLUCTUATE BETWEEN E AND SE AND REMAIN WEAK AT 5-10 KTS.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH LATE FRIDAY 
     NIGHT FOR NDZ006-014-015-024-026-028-029-038-039-049-052-
     053.

     WINTER STORM WATCH FROM THURSDAY MORNING THROUGH LATE FRIDAY 
     NIGHT FOR NDZ007-008-016-027-030-054.

MN...WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH LATE FRIDAY 
     NIGHT FOR MNZ003-029>031-040.

     WINTER STORM WATCH FROM THURSDAY MORNING THROUGH LATE FRIDAY 
     NIGHT FOR MNZ001-002-004>009-013>017-022>024-027-028-032.

&&

$$
TG/HOMANN