FXUS63 KABR 280930
AFDABR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
330 AM CST SAT NOV 28 2009

.SHORT TERM...THROUGH MONDAY

COOLER AIRMASS HAS BEGUN TO LEAK OUT OF CANADA THIS
MORNING...HOWEVER OVERNIGHT TEMPERATURES HAVE BEEN INFLUENCED MORE
BY MIXING/CLOUD COVER. SHORTWAVE THAT FLOWS OVERHEAD LATER TODAY
CONTINUES TO LOOK UNIMPRESSIVE. WITH ONLY BRIEF
UPGLIDE...WEAK/DISORGANIZED FORCING ELSEWHERE...AND AN ELIVATED
DENDRITIC GROWTH ZONE DISLOCATED FROM THE ABOVE INGREEDIENTS...AM
UNSUPPRISED THAT ONLY 4 ENSEMBLE MEMBERS SUGGEST MEASURABLE QPF.
WILL LEAVE ISOLD WORDING FOR ANY POPS...AND SUSPECT SYSTEM WILL BE
MAINLY A CLOUD PRODUCER. ANOTHER MODIFIIED PACIFIC AIRMASS SLIDES
OVERHEAD...WITH H85 TEMPERATURES RECOVERING BACK INTO THE
MID/UPPER SINGLE DIGITS C FOR MONDAY...ALONG WITH A WESTERLY WIND
COMPONENT ASSOCIATED WITH A WEAK SURFACE TROUGH.

.LONG TERM...MONDAY NIGHT THROUGH FRIDAY
STILL SOME UNCERTAINTY WITH THE LONG TERM FORECAST DUE TO MODEL
DISCREPANCIES...ESPECIALLY LATER IN THE PERIOD. AN UPPER LEVEL
TROUGH WILL BE OVER THE EASTERN UNITED STATES MONDAY NIGHT...WITH
A CUT OFF LOW OVER NORTHERN MEXICO. THE NORTHERN PLAINS WILL BE
UNDER NORTHWEST FLOW AHEAD OF AN APPROACHING SHORTWAVE TROUGH. THE
TROUGH DROPS OVER THE NORTHERN PLAINS TUESDAY...SLIGHTLY FASTER ON
THE GFS THAN THE ECMWF. SOME PVA LOOKS TO LINGER OVER THE REGION
THROUGH THE DAY WEDNESDAY. MODEL DIFFERENCES THEN BECOME
SIGNIFICANT...WITH THE GFS CONTINUING TO BE THE MOST AGGRESSIVE
PUSHING THE TROUGH EAST OF THE REGION AND BRINGING THE WESTERN
RIDGE OVER THE PLAINS BEFORE BRINGING ANOTHER STRONG SHORTWAVE
OVER THE DAKOTAS. THE ECMWF NEVER DOES BRING THE RIDGE NEAR THE
AREA DURING THE PERIOD...BUT KEEP BROAD TROUGHINESS FROM EASTERN
CANADA TO THE SOUTHERN PLAINS.

AT THE SURFACE...LOW PRESSURE WILL TRACK FROM SOUTHERN SASK TO
SOUTHERN MANITOBA MONDAY NIGHT...DRAGGING A COLD FRONT THROUGH
ABOUT THE WESTERN HALF OF THE CWA. THE LOW TRACKS TO THE WESTERN
GREAT LAKES TUESDAY...WITH THE FRONT EXITING THE CWA DURING THE
AFTERNOON. HIGH PRESSURE BROADENS FROM THE WESTERN UNITED STATES
TO THE PLAINS TUESDAY NIGHT. HIGH PRESSURE REMAINS OVER THE PLAINS
ON WEDNESDAY...THEN THE MODEL DIFFERENCES IN THE SURFACE PATTERN
BEGIN TO SHOW UP. THE ECMWF KEEPS THE HIGH OVER THE PLAINS THROUGH
THE DAY FRIDAY...THEN PUSHES IT EAST WITH A WEAK COLD FRONT
SLIDING ACROSS THE WESTERN DAKOTAS FRIDAY NIGHT. THE GFS SHOWS THE
HIGH GETTING PUSHED EAST ON THURSDAY AS A TROUGH ASSOCIATED WITH
LOW PRESSURE OVER SW SASK DIGS DOWN THE LEE OF THE ROCKIES. IT
THEN SHOWS THE LOW ELONGATING OVER THE PLAINS AND MOVING VERY
LITTLE ON FRIDAY. GENERALLY WENT WITH SOMEWHAT OF A BLEND OF THE
TWO MODELS FOR MONDAY NIGHT THROUGH WEDNESDAY NIGHT...THEN STUCK
WITH HPC FOR THURSDAY AND FRIDAY. LITTLE IN THE WAY OF MOISTURE
OR STRONG LIFT WITH EITHER OF THE FRONTS MOVING THROUGH...SO WILL
KEEP THE ENTIRE LONG TERM PERIOD DRY.

TUESDAY WILL BE THE WARMEST DAY OF THE PERIOD WITH WEAK WAA AHEAD
OF THE FIRST FRONTAL BOUNDARY. H85 TEMPS FALL WELL INTO THE TEENS
BELOW ZERO FOR THE REST OF THE PERIOD...SO WENT BELOW GUIDANCE FOR
TEMPERATURES...ESPECIALLY DAYTIME HIGHS...WITH MOST AREAS LIKELY
ONLY SEEING HIGHS IN THE 20S THURSDAY AND FRIDAY.

&&

.AVIATION...
VFR CONDITIONS WILL PREVAIL TODAY WITH BKN-OVC CIGS AOA 15K FEET. 
MID LEVEL CIGS AROUND 5K FEET WILL SET UP OVER THE REGION THIS
EVENING AND REMAIN OVERNIGHT. VSBYS WILL BE UNRESTRICTED.

&&

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

$$
SHORT TERM...CONNELLY
LONG TERM...PARKIN
AVIATION...PARKIN

WEATHER.GOV/ABERDEEN