FXUS63 KFGF 112036
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
235 PM CST FRI DEC 11 2009

.DISCUSSION...
FORECAST CHALLENGE CONCERNS TEMPERATURES AND PCPN CHANCES.  MODELS 
IN OVERALL GOOD AGREEMENT ALTHOUGH WILL USE BLEND AS CONTINUE TO 
PREFER DRIER NAM RH TRENDS.

REGION WILL CONTINUE TO TRANSITION IN MID LEVEL ZONAL PATTERN. WARM 
ADVECTION WILL LEVEL OFF TONIGHT AS WEAK BOUNDARY DROPS THROUGH FA 
EXITING REGION LATER SATURDAY. WITH BAROCLINIC ZONE PARALLEL TO FLOW 
AND LACK OF ANY SHORT WAVE TO DRIVE COLDER AIR SOUTH WE SHOULD BE 
ABLE TO SEE ONE MORE DAY BEFORE COLDER AIR MAKES ITS NEXT PUSH 
SOUTHWARD.

WILL SEE MORE CLOUD COVER OVERNIGHT INTO SATURDAY BASED ON UPSTREAM 
CLOUD TRENDS. THIS WILL LIMIT ANY BIG TEMPERATURE SWINGS TONIGHT 
INTO SATURDAY. WITH SOME FRONTOGENETIC FORCING AND DEEPER LAYERED RH 
ACROSS NORTHERN FA OVERNIGHT AND SPOTTY -SN FROM UPSTREAM METARS IN 
S CANADA WILL MAINTAIN LOW END POPS ACROSS NORTHERN TIER.

COLD ADVECTION BEGINS ITS MOVE SUNDAY AS WEAK WAVE CROSSES FA. WITH 
COLD ADVECTION AND DEEPER LAYERED RH SPREADING EAST WILL ALSO 
CONTINUE POPS. MINIMAL TEMPERATURE RECOVER EXPECTED AND WILL TREND 
TEMPERATURES TO LOW END OF GUIDANCE.

GFS COMING IN MORE IN LINE WITH NAM/ECMWF AND GEM BEING MORE GRADUAL 
WITH PUSH OF COLDER AIR ON MONDAY. WITH WEAKER UPSTREAM SURFACE HIGH 
GRADIENT NOT AS TIGHT. WITH COLD ADVECTION NOT AS SHARP AND FAIRLY 
WEAK WINDS ALOFT NOT EXPECTING ANY SERIOUS VSBY/WIND PROBLEMS AT 
THIS POINT.  SOME TROWEL POTENTIAL EARLY MONDAY FROM WEST CENTRAL MN 
INTO FAR SE ND HOWEVER FRONTOGENETIC FORCING LOOKS WEAK SO AT MOST 
COULD REACH ADVISORY CRITERIA FOR VARIETY OF FACTORS. WILL BE UPPING 
POPS SUNDAY NIGHT INTO MONDAY WITH WAVE PASSAGE. MAIN THREAT WILL 
LIKELY BE WIND CHILLS. PLAN ON UPDATING HWO TO ADDRESS NEXT PUSH OF 
COLD AIR...WIND CHILLS AND SNOW/BLSN IN OPEN AREAS. 

.LONG TERM...MONDAY NIGHT THROUGH FRIDAY

GFS/ECMWF/GEM/DGEX IN REASONABLE AGREEMENT SHOWING AN UPPER LEVEL 
SHORT-WAVE MOVING ACROSS THE FORECAST AREA MONDAY NIGHT INTO TUESDAY 
MORNING. THEREAFTER...THE LARGE-SCALE PATTERN WILL TRANSITION INTO A 
WEST COAST RIDGE AND EAST COAST TROUGH WITH NORTHWEST FLOW ALOFT 
ACROSS THE NORTHERN PLAINS. EACH MODEL SHOWS A SERIES OF WEAK WAVES 
MOVING THROUGH THE REGION LATE IN THE WEEK...BUT THERE EXIST TOO 
MANY DIFFERENCES TO INCLUDE ANY POPS AT THIS TIME. 

INSTEAD...THE BIG STORY FOR NEXT WEEK WILL BE A 1040 HPA CANADIAN 
SURFACE HIGH THAT MOVES ACROSS THE CENTRAL PLAINS. WITH 925 HPA 
TEMPERATURES FROM -10 TO -20 CELSIUS...THIS WILL RESULT IN CONTINUED 
COLD THROUGH WEDNESDAY MORNING WITH TEMPERATURES WELL BELOW ZERO. 
MODEST WARM-UP LOOKS TO BEGIN DURING THE DAY WEDNESDAY AND CONTINUE 
THROUGH THE END OF THE WEEK AS THERMAL RIDGE MOVES EAST. DAYTIME 
HIGHS THURSDAY/FRIDAY MAY BREAK THE 20 DEGREE MARK ACROSS THE 
SOUTHERN FORECAST AREA.   

&&

.AVIATION...

EXPECT VFR CONDITIONS AT ALL TAF AIRFIELDS THE NEXT 24 HOURS. 
SPORADIC CEILINGS SHOULD REMAIN AT OR ABOVE 5000 FT. LIGHT SOUTHERLY 
WINDS WILL SHIFT TO THE NORTH OVERNIGHT OR BECOME LIGHT AND VARIABLE 
AS CANADIAN HIGH PRESSURE BEGINS TO SLIDE SOUTH.      

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.

MN...NONE.

&&

$$
VOELKER