FXUS63 KFGF 100332 AAA
AFDFGF

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GRAND FORKS ND
932 PM CST WED DEC 9 2009

.DISCUSSION...MAIN CONCERN WILL BE TEMPERATURES AND WIND CHILL
VALUES. GIVEN CURRENT TEMP VALUES WILL NEED TO LOWER MIN TEMPS
ACROSS MOST AREAS BY AROUND 5F. THICKER LOWER CLOUDS WILL NOT
ENTER THE WESTERN FA UNTIL CLOSER TO MORNING. WIND SPEEDS ALONG
AND WEST OF THE RED RIVER VALLEY ARE MOSTLY BELOW 5 MPH
NOW...WHICH IS BELOW WIND CHILL ADVISORY CRITERIA. HOWEVER...THIS
HAS ALLOWED THE TEMPS TO FALL LOWER THAN EXPECTED. MOST MODEL
GUIDANCE DOES SUGGEST THAT THE WEAK SFC RIDGE ACROSS THIS AREA
WILL BE PUSHED SOUTH AS WEAK SYSTEM APPROACHES FROM THE NW. SFC
WINDS SHOULD AGAIN BE AOA 5MPH AFTER MIDNIGHT...AND WITH TEMPS
EVEN LOWER THAN PREVIOUSLY THOUGHT WILL NEED TO KEEP WIND CHILL
ADVISORY IN EFFECT. 

&&

.AVIATION...VFR (OR NO) CIGS THROUGH THE OVERNIGHT WITH NW WINDS
SHIFTING TO A LIGHTER WEST OVERNIGHT AS CYCLONE OVER LAKE MICHIGAN
MOVES TO THE EAST. MVFR CIGS POSSIBLE TOWARD THE AFTERNOON HOURS
ALONG AND WEST OF THE RED RIVER VALLEY. 

&&

.PREV DISCUSSION... /ISSUED 230 PM CST WED DEC 9 2009/ 

DISCUSSION...
FORECAST CHALLENGE CONCERNS TEMPERATURES AND NEAR TERM WCHILLS.

MODELS IN GOOD AGREEMENT AT LEAST THROUGH THE SHORT TERM AND WILL 
USE BLEND FOR FORECAST. 

TRICKY TONIGHT AS FAR AS TEMPERATURES AND WIND CHILLS GO. BIG STORM 
SYSTEM WILL CONTINUE TO LIFT NE THROUGH THE GREAT LAKES INTO S ONT 
ALLOWING GRADIENT TO RELAX ACROSS EASTERN FA. HIGH PRESSURE WILL 
BUILD OVER FA HOWEVER MAIN HIGH CENTERS WILL BE TO THE NORTH AND 
SOUTH OF US KEEPING SOME SORT OF WESTERLY SURFACE FLOW GOING 
OVERNIGHT. THERMAL ADVECTION WILL BE NEUTRAL LEADING TO CLOUD TRENDS 
AS MAIN TEMPERATURE DRIVER. LOWER CIGS CONTINUE ACROSS FAR EASTERN 
FA AND WILL HAVE SOME IMPACT ON EVENING TEMP DROP. NW FA MAY SEE 
MINIMUM TEMPERATURES PRIOR TO MIDNIGHT OR CLOSE TO BEFORE LOWER CIGS 
IN E MT MOVE IN AND LEVEL OFF TEMPERATURES. REMAINDER OF FA WILL BE 
IN AND OUT OF THICKER CI AND WITH COLD MAX TEMPERATURES SHOULD NOT 
HAVE MUCH PROBLEM DROPPING TO OR BLO LOW END OF NUMERICAL GUIDANCE. 
ONCE LOW CLOUDS MOVE OUT OF THE EAST THIS AREA SHOULD ONLY BE 
AFFECTED BY PATCHY HIGH CLOUDS ALLOWING FOR GRADUAL DROP. 

AS FAR AS HEADLINES...DECIDED TO EXTEND ADVISORY IN DVL BASIN AS 
TEMPERATURES HAVE STRUGGLED TO REACH 10 BELOW AND SOME WIND 
CONTINUING. TEMPERATURES THIS AREA WILL CONTINUE TO DROP BEFORE 
LEVELING OFF AFT MIDNIGHT. FARTHER EAST IN THE VALLEY WINDS LIKELY 
TO DROP OFF THIS EVENING AND A WEST WIND IS NOT FAVORABLE THROUGH 
VALLEY SO WINDS MAY STAY ON LOW END. HOWEVER WITH 5 MPH WIND 
CRITERIA FOR ADVISORY WILL NEED TO RE ISSUE.

REGION WILL REMAIN IN NW FLOW ALOFT THURSDAY. LOW LEVEL WESTERLY 
FLOW WILL CONTINUE WITH ONLY HINT OF WARM ADVECTION ACROSS SW FA 
DURING AFTERNOON. INCREASING RH THROUGH COLUMN SHOULD RESULT IN 
CLOUD COVER EXPANDING ACROSS FA WHICH SHOULD TEMPER RADIATIONAL 
COOLING. WILL STILL HAVE TO TREND TEMPERATURES COLDER THAN NUMERICAL 
GUIDANCE. 

UPPER LEVELS TRANSITION INTO MORE ZONAL FLOW HEADING INTO THE 
WEEKEND WITH BEST WARM ADVECTION ACROSS SOUTH HALF OF FA. THIS 
COMBINED PLENTY OF CLOUDS FROM MODEL TIME SECTIONS NOT A WIDE 
VARIANCE IN TEMPERATURES EXPECTED.      

LONG TERM (SAT NIGHT-WEDNESDAY)...

UPPER AIR PATTERN DEPICTED BY MAJOR GUIDANCE PRODUCTS 
ARE CONSISTENT WITH A ZONAL START TO THE EXTENDED PERIOD...WITH 
STRONGLY DIVERGENT SOLUTIONS THEREAFTER. ECMWF CONTINUES THE 
TREND OF POLAR VORTEX WELL NORTH OVER CENTRAL CANADA. GFS BRINGS 
THIS LOW CLOSE TO THE INTERNATIONAL BORDER...WITH A DEFINED SURFACE 
SYSTEM...0.25 INCH QPF AND WINDS ABOVE 15 KTS. AS THIS IS THE 
CURRENT OUTLIER...WE'LL CONTINUE WITH THE DRY HPC COLLABORATED 
FORECAST FOR DAY 6 TUES WITH WED DRY AS WELL. TEMPS REMAIN WELL 
BELOW NORMAL THROUGH THE PERIOD...BUT MODEST WARM AIR ADVECTION BY 
WED AFTERNOON COULD RESULT IN 10 DEGREE ABOVE HIGHS FOR SOME AREAS 
FOR THE FIRST TIME IN OVER A WEEK.            

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...WIND CHILL ADVISORY UNTIL NOON CST THURSDAY FOR NDZ006>008-
     014>016-024-026>030-038-039-049-052>054.

MN...WIND CHILL ADVISORY UNTIL NOON CST THURSDAY FOR MNZ001>009-
     013>017-022>024-027>032-040.

&&

$$
TG