FXUS63 KFGF 292105
AFDFGF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
305 PM CST SUN NOV 29 2009
.SHORT TERM...MAIN CONCERN WILL BE WIND POTENTIAL ON TUESDAY.
CHALLENGES WILL BE MINOR CLIPPER SYSTEM ON MON...AND THEN STRONGER
SYSTEM THAT WILL TRACK NEAR THE INTERNATIONAL BORDER TUESDAY INTO
WEDNESDAY. 12Z MODELS INITIALIZED WITH MINIMAL ERRORS. WHEN
COMPARING MODELS...GOOD AGREEMENT THROUGH MONDAY. MODELS ARE
COMING INTO BETTER AGREEMENT WITH THE TUE-WED SYSTEM. TREND IS
TOWARD THE MORE SOUTHERLY TRACK THE NAM HAS BEEN SHOWING THE PAST
FEW RUNS. ECMWF/GEM/GFS ALL SHOW THIS TRACK NOW...WITH THE GFS A
SLOW OUTLIER. WILL FOLLOW NAM FOR DETAILS.
TONIGHT-MONDAY...CURRENT CLOUD COVER IS MOVING EAST AS EXPECTED
(850MB WINDS NOW MORE WESTERLY). WEAK SYSTEM (NOSE OF STRONG UPPER
JET) WILL APPROACH TONIGHT WITH SKIES BECOMING MOSTLY CLOUDY BY
MORNING. MIN TEMP FORECAST CHALLENGE WILL BE HOW MUCH WILL VALUES
FALL BEFORE CLOUD COVER ARRIVES. BEST GUESS IS LOW TO MID
20S...BUT EVENING SHIFT WILL NEED TO MONITOR. VERY LIGHT SNOW OR
FLURRIES POSSIBLE ALONG AND EAST OF THE VALLEY TOWARD SUNRISE AND
INTO EARLY MONDAY AFTERNOON GIVEN THE POSITION OF THE LEFT EXIT
REGION OF UPPER JET. THE SCHC -SN CURRENTLY FORECASTED LOOKS
REASONABLE. EXPECT CLOUDS TO LINGER ACROSS THE EAST THROUGH MUCH
OF THE DAY...BUT CLEAR ACROSS THE WEST. OBVIOUSLY CLOUD POSITION
WILL IMPACT MAX TEMPS...BUT WHERE SKIES DO CLEAR LOW-MID 40S
SHOULD OCCUR. LOW-MID 30S UNDER CLOUD COVER.
MON NIGHT-WED...UPPER WAVE TO DIG INTO THE FA FROM THE NW WITH AN
ASSOCIATED SFC LOW TRACKING ACROSS THE NORTHERN FA (ACCORDING TO
LATEST GUIDANCE)...THEN QUICKLY PROPAGATING OFF TO THE EAST ON
WEDNESDAY. GIVEN THIS TRACK...GREATEST THREAT FOR HEAVY SNOW
ACCUMULATION WILL BE JUST NORTH OF THE FA. WITH THE SOLUTION NOW
FURTHER SOUTH THAN BEFORE...WILL INCREASE POPS ACROSS THE EXTREME
NORTHERN FA INTO CHANCE CATEGORY AS AN INCH OR TWO OF SNOW IS NOW
POSSIBLE. KEPT SCHC OR FLURRIES FURTHER SOUTH. MIN TEMPS TUE
MORNING SHOULD NOT FALL TOO FAR AS WARM AIR ADVECTION/SOUTHERLY
FLOW KICKS IN...PROBABLY MID-UPPER 20S. 850MB TEMPS CRASH HARD
THROUGH THE DAY ON TUE...BUT 925MB THERMAL RIDGE LAGS A BIT AND
THINK THAT THE SOUTHERN 2/3RDS OF THE FA WILL REACH INTO THE LOWER
40S BEFORE BEGINNING TO FALL EARLY OR MID AFTERNOON. NORTHERN
1/3RD A BIT COOLER...WITH TEMPS STEADY OR FALLING THROUGH MUCH OF
THE AFTERNOON. CLOUDS TO INVADE THE FA TUE AFTERNOON...AND MOST
LIKELY REMAIN INTO WEDNESDAY. WITH CONTINUED MIXING AND CLOUD
COVER TUE NIGHT...DID RAISE MIN TEMPS (THINKING MID 20S OPPOSED TO
TEENS/LOW 20S). COOLER AIRMASS AND CLOUD COVER SHOULD LIMIT TEMP
RISE ON WED...PROBABLY ONLY MID TO UPPER 20S.
WIND ADVISORY CONDITIONS LOOKING LIKE A DECENT BET ON TUESDAY
SOMEWHERE ACROSS EASTERN NORTH DAKOTA INTO THE VALLEY COUNTIES.
COLD AIR ADVECTION COMBINED WITH 925MB WINDS AROUND 30-35KNTS AND
850MB WINDS 45-50KNTS SHOULD BE SUFFICIENT. FAIRLY CLOSE TO ADIABATIC
UP TO 850MB...AND ALMOST UNIDIRECTIONAL AS WELL. EXACT TRACK OF
SYSTEM WILL DETERMINE WHERE MAIN CORE OF STRONGEST WINDS ALOFT
WILL BE. ONE MAIN INGREDIENT MISSING THAT SHOULD KEEP WINDS BELOW
WARNING CRITERIA IS THE STRONGEST PRESSURE RISE MAXIMUM WILL
PROPAGATE THROUGH THE FA TUE NIGHT. WINDS WILL REMAIN ELEVATED
WITH THIS FEATURE AND STRONG WINDS ALOFT...BUT NIGHTTIME SHOULD
LIMIT MIXING POTENTIAL SOME. CURRENT HWO HIGHLIGHTS WINDS.
.LONG TERM (THU-SAT)...THE MAIN CHALLENGE IN THE LONG TERM
INCLUDE DETERMINING HOW QUICKLY THE UPPER MIDWEST 500 MB TROUGH
WILL ADVANCE EASTWARD TO BRING IN SURFACE HIGH PRESSURE TO THE
NORTHERN PLAINS. ANOTHER CHALLENGE IS POSED BY POOR MODEL
DISAGREEMENT ON HOW QUICKLY A POSSIBLE FOLLOWUP UPPER LEVEL LOW
COULD SWING OUT OF THE ROCKIES TO GIVE THE NORTHERN PLAINS ANOTHER
CHANCE OF PRECIPITATION LATE IN THE WEEK. THE GFS AND DGEX ARE
MORE PRONOUNCED AND PROGRESSIVE SOLUTIONS COMPARED TO THE ECMWF
AND GEM...BUT EACH MODEL MODEL HAS BEEN SOMEWHAT CONSISTENT TO ITS
RESPECTIVE...PREVIOUS RUN. LEANING ON THE SLOWER...AND THEREFORE
DRIER...ECMWF.
SOME FLURRIES MAY CONTINUE THROUGH MONDAY NIGHT AS THE UPPER LEVEL
LOW OVER THE UPPER MIDWEST GRADUALLY PUSHES EAST ACROSS THE GREAT
LAKES. THURSDAY SHOULD BEGIN TO DRY OUT...BUT WILL LIKELY REMAIN
CLOUDY...AS HIGH PRESSURE BUILDS INTO THE NORTHERN PLAINS. THINK THE
GFS AND DGEX ARE TOO FAST...SO LEANED ON THE SLOWER ECMWF AND GEM.
THINK THE CLOUDY SKIES...NORTHWEST WINDS...AND COLD 925 MB
TEMPERATURES AROUND -10 TO -12 DEGREES CELSIUS WARRANTED COOLING
THURSDAY HIGH TEMPERATURES A FEW DEGREES.
REALIZE THE GFS AND DGEX BRING IN A ANOTHER CLIPPER SYSTEM FRIDAY
INTO SATURDAY...BUT THINK THEY ARE TOO FAST. THEREFORE...THINK THE
ECMWF AND GEM HAVE IT MORE RIGHT DURING THIS TIME WITH HIGH PRESSURE
STILL INFLUENCING THE NORTHERN PLAINS. THIS MAKES FOR A COOL AND
PARTLY SUNNY END TO THE WEEK.
&&
.AVIATION...EXPECT VFR CIGS AND VSBYS THROUGH TOMORROW
MORNING...BUT WITH A POSSIBILITY OF MVFR CIGS TOMORROW MORNING IN
THE WAKE OF A PASSING WEAK TROUGH OF LOW PRESSURE. WINDS WILL
REMAIN LIGHT AND WESTERLY THROUGH EARLY TOMORROW MORNING...BUT
WILL BECOME GUSTY AND NORTHWESTERLY AFTER DAWN. THE STRONGEST WIND
GUSTS OF 20 TO 25 KNOTS ARE EXPECTED AT DVL.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
TG/GROCHOCINSKI
