FXUS63 KABR 010255
AFDABR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
855 PM CST MON NOV 30 2009

.UPDATE...
ONCE AGAIN TEMPERATURES DROPPED OFF A BIT FASTER THAN ORIGINALLY
ANTICIPATED. ADJUSTED TEMPERATURE TREND AS NECESSARY. HOWEVER...WITH
DEWPOINTS RELATIVELY UNCHANGED AND SOME SKY COVER
APPROACHING...LEFT OVERNIGHT LOWS ALONE. THIS WAS THE ONLY MAJOR
CHANGE NECESSARY.

&&
.PREV DISCUSSION...
.SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT
MILD PACIFIC AIR ALOFT IN THE ATMOSPHERE IS MIXING DOWN TO THE SFC
WITH WESTERLY WINDS. TEMPERATURES ARE WELL ABOVE NORMAL THIS
AFTERNOON WITH READINGS IN THE UPPER 40S TO NEAR 60 DEGREES. A
CHANGE IN THE WEATHER PATTERN WILL OCCUR OVER THE NEXT COUPLE DAYS
AS MUCH COLDER AIR MAKES ITS WAY INTO THE REGION. SIGNS OF THIS
ARE SHOWING UP ACROSS CANADA AS UPPER TROUGH IS GAINING STRENGTH
AND COLD AIR IS BUILDING. THIS AIR MASS WILL BE SLIDING SOUTHEAST
INTO THE NORTHERN PLAINS OVER THE NEXT COUPLE DAYS. A COLD FRONT
WILL MOVE ACROSS THE REGION ON TUESDAY...SIGNALING THE CHANGE TO
COLDER WEATHER. BEHIND THIS FRONT NORTHWEST WINDS WILL INCREASE
AND BECOME BREEZY/WINDY. MAY BE FLIRTING WITH WIND ADVISORY
CRITERIA...APPEARS LIKE A MARGINAL EVENT AT THIS POINT SO WILL NOT
ISSUE ANY HEADLINES AT THIS TIME. MID SHIFT WILL NEED TO TAKE A
CLOSER LOOK THOUGH. GUIDANCE NUMBERS ARE JUST BELOW CRITERIA.
SOUNDINGS MIX UP TO 800MB...WHERE ABOUT 40 KNOTS OF WIND EXIST SO
GUSTS COULD BE NEAR 45 MPH. THE COLD AIR WILL CONTINUE TO OOZE
INTO THE REGION THROUGH THE END OF THE SHORT TERM PERIOD. HIGHS ON
WEDNESDAY ARE ONLY EXPECTED TO BE IN THE 20S TO NEAR 30 DEGREES.
SCT FLURRIES OR VERY LIGHT SNOW SHOWERS ARE POSSIBLE WEDNESDAY
AFTERNOON THROUGH THURSDAY AS STEEP LOW LEVEL LAPSE RATES COMBINE
WITH ADEQUATE MOISTURE ALOFT AND WEAK LIFT ASSOCIATED WITH
CYCLONIC FLOW.

.LONG TERM...12Z THURSDAY THROUGH SUNDAY
THE BIGGEST FORECAST CHALLENGE FACING THE LONG TERM STILL REVOLVES
AROUND THE MODELS BEING UNABLE TO CONVERGE TOWARD A COMMON
SOLUTION. 

BEGINNING AT 12Z THURSDAY THE MODELS ARE ACTUALLY FAIRLY CLOSE IN
THE BROAD DETAILS. LONGWAVE 500 HPA TROF IS DROPPING THROUGH THE
CWA..WITH THE GFS SHOWING A CLOSED LOW OVER KABR AND THE EC A
POSITIVELY TILTED TROF. 850HPA TEMPS ARE FAIRLY CLOSE AS
WELL...WITH STRONG CAA BEING ADVERTISED THROUGH THE DAY THURSDAY.
LOOKING AT THE COND PRESSURE DEFICITS FROM 925HPA THROUGH 500HPA
ON THE NAM/GFS/EC...ABUNDANT LOW/MID LEVEL CLOUDS SHOULD BE
PRESENT IN STRONG CYCLONIC FLOW AROUND DEPARTING SFC LOW. LAPSE
RATES AREN'T TOO TERRIBLY IMPRESSIVE...BUT MODELS DO HINT AT MINOR
AMOUNTS OF 700HPA OMEGA LINGERING IN CYCLONIC FLOW. WENT WITH
SCATTERED FLURRIES FOR THURSDAY...BUT THINK THAT EVEN THAT MIGHT
BE A BIT BOLD IN THE PRECIPITATION DEPARTMENT. 

AFTER THAT THE MODELS CONT TO DIVERGE FROM A COMMON SOLUTION. THE
GFS BRINGS ANOTHER STRONG 500HPA WAVE INTO THE NORTHERN PLAINS FOR
THE FIRST PART OF THE WEEKEND...WHILE THE EC SHOWS THIS FEATURE
MUCH FARTHER TO THE WEST AND CLOSED OFF IN APPEARANCE. THE
CANADIAN/CANADIAN ENSEMBLES LEAN TOWARD THE CLOSED OFF SOLUTION OF
THE EC...BUT PLACE THIS FEATURE MORE INTO THE ROCKIES THAN THE
WESTERN CONUS COAST...WHILE THE NAEFS IS LEAST PROGRESSIVE OF THE
LONG TERM MODELS. THE GFS HINTS AT THE POSSIBILITY OF MORE
POTENTIAL FOR PCPN...WHILE THE EC AND OTHERS ARE LESS IMPRESSED.
DUE TO THE LACK OF COMMONALITY BETWEEN THE MODELS...AND VERY LOW
CONFIDENCE IN THE PCPN ASPECT...HAVE CONTINUED THE DRY FORECAST
THROUGH THE EXTENDED UNTIL THINGS GET TO BE A BIT CLEARER. 

TEMP WISE...WITH SUB -10C AIR COMING IN FOR THE WEEKEND ON BOTH
MODELS...HAVE CONTINUED TREND OF LOWERING TEMPS FOR FRIDAY AND
SATURDAY. THANKFULLY GROUND IS BARE. IF SNOW WERE PRESENT WE WOULD
BE LOOKING AT SUB-ZERO TEMPS BY THE WEEKEND FOR OVERNIGHT LOWS. 

&&

.AVIATION...
AREAS OF HIGH CLOUDS AOA 20000 FEET ARE MOVING IN...BUT VFR
CONDITIONS ARE EXPECTED TO PERSIST THROUGH TONIGHT AND ON INTO
TUESDAY. WINDS LOOK TO BE RATHER STRONG AND PERHAPS GUSTY
TUESDAY...BECOMING NORTHWESTERLY AS A COLD FRONT PUSHES THROUGH.

&&

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

$$
UPDATE...GIONTA
SHORT TERM...TMT
LONG TERM...HINTZ
AVIATION...GIONTA

WEATHER.GOV/ABERDEEN