FXUS63 KABR 270336
AFDABR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
936 PM CST THU NOV 26 2009

.UPDATE...
CURRENT FORECAST IS DOING VERY WELL. TEMPERATURES ARE RIGHT ON
TRACK AS WELL AS THE OTHER FORECAST ELEMENTS. NO UPDATES PLANNED
FOR TONIGHT.

&&
.PREV DISCUSSION...
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
THE MODELS AGREE WELL THROUGH THE SHORT TERM WITH A WARM FRONT
MOVING IN FROM THE WEST TONIGHT...AN UPPER RIDGE MOVING OVER THE
REGION FRIDAY INTO FRIDAY NIGHT...FOLLOWED BY A COLD FRONT FRIDAY
NIGHT AND SATURDAY. FINALLY FOR SATURDAY NIGHT...AN UPPER LEVEL
TROUGH IN THE NORTHERN STREAM WILL BRING INCREASING CLOUDS ALONG
WITH THE SLIGHT POSSIBILITY OF LIGHT SNOW SHOWERS/FLURRIES SATURDAY
NIGHT. FOR TONIGHT...THE WARM FRONT ACROSS WESTERN SOUTH DAKOTA
WILL MAKE ITS WAY EAST. WITH QUICK COOLING THIS EVENING AT THE
SURFACE ALONG WITH NOT MUCH FOR WIND...MOST OF THIS WARM AIR WILL
REMAIN ALOFT TONIGHT AS IT MOVES EAST. WITH A STRONG INVERSION
SETTING UP WITH LIGHT WINDS AT THE SURFACE...COULD GET SOME PATCHY
FOG AGAIN TONIGHT. ALTHOUGH...WITH HIGH LEVEL CLOUDS SPILLING OVER THE
RIDGE OUT WEST...THESE CLOUDS MAY KEEP FOG FROM FORMING TONIGHT. WILL
LEAVE THE FOG OUT FOR NOW. FOR FRIDAY...WITH A BROAD AREA OF
SURFACE LOW PRESSURE ACROSS THE REGION...THE WINDS WILL CONTINUE
ON THE LIGHT SIDE. THUS...DESPITE HAVING VERY WARM AIR OVER THE
REGION...IT WILL BE DIFFICULT TO BRING MUCH OF THIS WARM AIR DOWN
TO THE SURFACE WITH ONLY LATE NOVEMBER SUN TO WARM THE SURFACE AND
INCREASE THE DEPTH OF THE MIXING LAYER. DESPITE A SHALLOW MIXING
LAYER...TEMPERATURES WILL STILL WARM INTO THE 50S ACROSS THE CWA
WITH SUNNY SKIES UNDER THE UPPER RIDGE ON FRIDAY.

THE UPPER RIDGE MOVES EAST FRIDAY NIGHT AND SATURDAY AS CAA
BEGINS ON THE BACKSIDE OF THE SURFACE TROUGH. WITH THE CAA ALONG
WITH A TIGHTENING SURFACE PRESSURE GRADIENT AND PACIFIC HIGH
PRESSURE BUILDING IN FROM THE WEST...NORTHWEST WINDS SHOULD PICK
UP ON SATURDAY...ESPECIALLY DURING THE AFTERNOON AND COULD BECOME
BREEZY/WINDY. OTHERWISE...CLOUDS WILL BE INCREASING FROM THE
APPROACHING UPPER LEVEL TROUGH WITH HIGHS ABOUT 10 DEGREES COOLER
THAN FRIDAY. NOT MUCH MOISTURE AVAILABLE WITH THE TROUGH AFFECTING
THE REGION SATURDAY NIGHT WITH MAINLY MID LEVEL MOISTURE. MODELS
NOT TOO KEEN ON ANY QPF ON SATURDAY NIGHT. LEFT THE SLIGHT CHANCE
IN AT THIS TIME AND MAY HAVE TO TAKE IT OUT IN THE NEXT FORECAST.

.LONG TERM...SUNDAY THROUGH WEDNESDAY
AT THE START OF THE PERIOD MODELS SHOW A SHORTWAVE TROUGH PASSING
TO THE SOUTHEAST OF THE AREA AND DOES NOT LOOK TO BRING ANY
PRECIPITATION TO THE REGION. THIS WAVE DOES BRING DOWN RATHER
CHILLY AIR AS 850MB TEMPS DROP INTO THE SINGLE DIGITS BELOW ZERO.
THIS COLD AIR IS QUICKLY REPLACED BY WARMER AIR WITH AN
APPROACHING WEAK RIDGE AS 850MB TEMPS RISE BACK INTO THE SINGLE
DIGITS ABOVE ZERO. MAIN STORY IN THE LONG TERM IS THE TREND TO A
COLDER WEATHER PATTERN THAT MODELS ARE SHOWING TOWARDS THE MIDDLE
AND END OF NEXT WEEK. DIFFERENCES STILL NOTED IN THE MODELS AS TO
WHERE EXACTLY THE LARGE UPPER TROUGH ORIENTS ITSELF ACROSS THE
UPPER MIDWEST/GREAT LAKES REGION. WHERE EXACTLY THIS SETS UP WILL
DETERMINE JUST HOW COLD WE GET BUT ALL MODELS ARE SHOWING 850 MB
TEMPS DROPPING DOWN INTO THE TEENS BELOW ZERO. AIR THIS COLD
SUGGESTS HIGHS IN THE 20S WITH LOWS IN THE SINGLE DIGITS.
INHERITED HPC GRIDS HAVE BEGUN TRENDING TOWARDS THESE VALUES...AS
ARE THE NEWEST MEX GUIDANCE NUMBERS.

&&

.AVIATION...
VFR CONDITIONS WILL CONTINUE THROUGH TOMORROW WITH JUST A FEW HIGH
CLOUDS DRIFTING ACROSS THE UPPER LEVEL RIDGE. VISIBILITY WILL ALSO
BE UNRESTRICTED THROUGH TOMORROW.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&

$$
UPDATE...KEEFE
SHORT TERM...MOHR
LONG TERM...TMT
AVIATION...KEEFE

WEATHER.GOV/ABERDEEN