FXUS63 KGID 282247
AFDGID
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
447 PM CST SAT NOV 28 2009
.AVIATION...00Z TAF. A COLD FRONT PASSED THROUGH KGRI EARLIER
TODAY WITH SURFACE PRESSURE RISES AND A TIGHT PRESSURE GRADIENT
FOLLOWING THE FRONT. NORTH WINDS GUSTING OVER 20KTS ARE COMMON
BEHIND THE FRONT...AND ALTHOUGH WE ARE HEADED TOWARD A LESS
FAVORABLE TIME FOR STRONGER WINDS...DO BELIEVE THE GRADIENT
AND MIXING THIS EVENING WILL BE ENOUGH FOR SUSTAINED WINDS
ABOVE 15KTS AND GUSTS OVER 20KTS AT TIMES. THE GUSTS SHOULD
TAPER OFF A BIT LATE IN THE EVENING. OTHERWISE...COPIOUS
AMOUNTS OF HIGH CIRRUS LEVEL CLOUDS WILL PERSIST THROUGH
MIDDAY SUNDAY. THERE MAY BE A BRIEF PERIOD OF LOW END VFR
CIGS NEAR 3K FOR A TIME OVERNIGHT...AND HAVE ADDED THAT
AS TEMPO PERIOD AFTER MIDNIGHT.
&&
.PREV DISCUSSION... /ISSUED 312 PM CST SAT NOV 28 2009/
SHORT TERM....TONIGHT THROUGH 12Z MONDAY...MAIN FORECAST CONCERNS
WILL BE CLOUD COVER AND TEMPERATURES.
THIN CIRRUS CONTINUES TO MOVE ACROSS THE FORECAST AREA THIS
AFTERNOON. SURFACE ANALYSIS INDICATES THAT THE WEAK COLD FRONT HAS
NEARLY MOVED OUT OF THE FORECAST AREA...WITH JUST THE FAR SOUTHEAST
HAVING LIGHT WINDS FROM THE SOUTH. MUCH OF THE FORECAST AREA HAS
NORTH TO NORTHEAST WINDS AROUND 10 MPH.
THE COLD FRONT WILL CONTINUE TO MOVE TO THE SOUTHEAST OUT OF THE
FORECAST AREA EARLY THIS EVENING. THE SURFACE GRADIENT TIGHTENS
TONIGHT AND WITH CAA ALOFT EXPECT THAT WINDS WILL STAY UP TONIGHT.
THERE IS ALSO SOME MOISTURE AND A WEAK UPPER TROUGH THAT WILL MOVE
THROUGH THE AREA TONIGHT. EXPECT THAT LATER TONIGHT THERE WILL BE
INCREASING CLOUDS AND WITH THE WINDS THERE WILL NOT BE AS MUCH
RADIATIONAL COOLING SO TEMPERATURES WILL BE A BIT WARMER TONIGHT
DESPITE THE COLD FRONT.
A WEAK SURFACE HIGH SPREADS INTO THE AREA SUNDAY WHICH SHOULD ALLOW
CLOUDS TO DECREASE AGAIN DURING THE DAY. THE CAA CONTINUES DURING
THE DAY AND 850MB TEMPERATURES REMAIN COOL DURING THE DAY. EXPECT
TEMPERATURES TO BE COOLER TOMORROW BUT WINDS SHOULD BE A LITTLE
LIGHTER. THE SURFACE HIGH SLIDES TO THE SOUTH SUNDAY NIGHT. WITH
LESS CLOUDS AND LIGHTER WINDS EXPECT THAT TEMPERATURES WILL BE
COOLER SUNDAY NIGHT THAN TONIGHT.
LONG TERM...12Z MONDAY THROUGH NEXT SATURDAY.
MONDAY INTO THE FIRST HALF OF TUESDAY CONTINUE TO LOOK MILD AND DRY
ACROSS THE REGION AS THE AREA IS STUCK IN A SPLIT FLOW PATTERN. THIS
REGIME WILL BE DOMINATED BY A CLOSED LOW SPINNING SLOWLY EAST FROM
THE DESERT SOUTHWEST INTO THE SOUTHERN PLAINS WHILE A PROGRESSIVE
NORTHERN STREAM IS SEEN RUNNING ALONG THE CANADIAN BORDER. THIS WILL
KEEP A FRAGMENTED SURFACE TROUGH STRUCTURE OVER THE CENTRAL PLAINS
MONDAY INTO EARLY TUESDAY WITH WEST TO SOUTHWEST WINDS PREVAILING
ACROSS THE REGION. UNDER THIS SETUP...MILD AND DRY CONDITIONS WILL
PREVAIL BOTH DAYS AS TEMPERATURES CLIMB INTO THE MID 50S TO MID
60S FOR HIGHS.
THE WEATHER PATTERN THEN TAKES A NOSE DIVE TUESDAY NIGHT AND LASTING
INTO THURSDAY AS THE MODELS ARE BEGINNING TO CENTER AROUND A LARGE
VORTEX FORMING WITHIN A TROUGH AXIS SOMEWHERE BETWEEN THE HUDSON BAY
TO GREAT LAKES REGION. THIS PHASED UPPER TROUGH WILL ALLOW MODIFIED
ARCTIC AIR TO SPILL SOUTHWARD OUT OF CANADA WITH A STRONG COLD FRONT
PROGGED TO BLOW THROUGH THE FORECAST AREA TUESDAY NIGHT. ALTHOUGH
STRONG CAA WILL EXIST BEHIND THE FRONT...MID TO UPPER FORCING ON THE
BACK SIDE OF THE UPPER TROUGH WILL BE MARGINAL AT BEST AND ALONG
WITH A FAIRLY DRY LOWER 10 KFT OF THE ATMOSPHERE...INDICATES
PRECIPITATION CHANCES WILL BE SLIM AT BEST. CAN/T COMPLETELY RULE
OUT A FEW SNOW FLURRIES BUT WILL OPT TO KEEP THE FORECAST DRY. THE
MAIN STORY FOR WEDNESDAY AND THURSDAY SHOULD BE THE DROP IN
TEMPERATURES BEHIND THE FRONT AS 850MB TEMPERATURES ARE PROGGED TO
DROP INTO A -5C TO -10C RANGE BY WEDNESDAY NIGHT INTO THURSDAY.
DESPITE THIS COLD AIR...CLOUD COVER IS SHOWN TO BE MINIMAL AND WITH THE
COLDEST AIR STAYING CLOSER TO THE GREAT LAKES...EXPECT DECENT MIXING
TO PROVIDE HIGHS IN THE 30S TO POSSIBLY NEAR 40 BOTH DAYS.
MANY QUESTIONS THEN EXIST FOR LATE FRIDAY INTO SATURDAY AS THE
MEDIUM RANGE MODELS ARE SHOWING A WIDE SPREAD IN POSSIBLE SOLUTIONS
WITH THE EVOLUTION OF THE UPPER PATTERN ACROSS THE WESTERN HALF OF
THE CONUS. THE 12Z GFS HAS POSITIVELY TITLED TROUGH SITTING FROM THE
NORTHERN PLAINS INTO THE INTERMOUNTAIN WEST...THE 06Z GFS HAS A
RIDGE OVER THE CENTRAL CONUS...THE 12Z ECMWF FROM TODAY HAS A RIDGE
OVER THE CENTRAL CONUS WHILE A STRONG WAVE IS SEEN DIGGING INTO THE
PACIFIC NORTHWEST...THE 00Z ECMWF HAS A COOL BUT PROGRESSIVE
NORTHWEST FLOW...THE 12Z ECMWF FROM YESTERDAY HAS A VERY COLD NORTH
TO NORTHWEST FLOW REGIME WITH THE UPPER RIDGE SITTING OFF THE WEST
COAST...PROGGED TO BE ROUGHLY 10 DEG LONGITUDE FURTHER WEST THAN THE
00Z ECMWF. THE GFS AND ECMWF ENSEMBLE DATA IS OF LITTLE HELP WITH
THIS TIME PERIOD AS ENSEMBLE MEMBERS ARE DISPLAYING A WIDE SPREAD IN
POSSIBLE SOLUTIONS. GIVEN ALL OF THIS INFORMATION...HAVE LITTLE
CONFIDENCE IN PICKING ANY OF THESE SOLUTIONS AND WILL OPT TO GO
CLOSER TO A PERSISTENCE/CLIMO FORECAST FOR FRIDAY AND SATURDAY WHICH
MATCHES THE HPC FORECAST FOR DRY CONDITIONS WITH HIGHS IN THE 30S.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
