FXUS63 KABR 261808 AAA
AFDABR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
1208 PM CST SAT DEC 26 2009
.UPDATE...REST OF TODAY
BLIZZARD WARNING WAS SET TO EXPIRE AT 18Z. AFTER COLLAB WITH OTHER
OFFICES AND EXAMINATION OF OBS/WEB CAMS/PUBLIC REPORTS/RADARS HAVE
DECIDED TO EXTEND BLIZZARD WARNING UNTIL 00Z WEST OF THE MISSOURI
RIVER AND REPLACE IT WITH A WINTER WX ADVISORY EAST OF THE RIVER.
STILL EXPERIENCING PERIODIC REDUCTIONS IN VSBYS ACROSS EASTERN SD
AS NORTHWEST WINDS FROM 20 TO 35 MPH REMAIN IN PLACE. CONDITIONS
ARE A BIT WORSE ACROSS WESTERN SD WHERE A MORE STEADY SNOWFALL AND
STRONGER WINDS FROM 25 TO 45 MPH ARE IN PLACE. REPORTS ACROSS
STANLEY AND CORSON COUNTIES...AS WELL AS WEB CAMS JUST TO THE WEST
OF THE CWA VERIFY CONTINUED BLIZZARD CONDITIONS AT TIMES. WILL
THEREFORE EXTEND THE BLIZZARD WARNING ACROSS THE FAR WESTERN CWA
UNTIL 00Z. THE REST OF THE FORECAST IS IN FINE SHAPE AND ONLY
MINOR CHANGES WERE MADE.
&&
.PREV DISCUSSION...
.SHORT TERM...THROUGH MONDAY
LOW PRESSURE CONTINUES TO SHIFT EAST...WITH VORT LOBES
PINWHEELING BACK INTO THE CWA. ONE SUCH FEATURE IS MOVING ACROSS
THE KMBG AREA...WHILE A SECOND IS MOVING OUT OF MN. THIS WILL MARK
THE END TO THE BRIEF BENIGN CONDITIONS THAT HAVE EXISTED THROUGH
THE MORNING UNDER A DRY SLOT. WITH A WEAKENING...NEARLY BAROTROPIC
SYSTEM...RELAXING PRESSURE GRADIENT AND LESS INTENSE SNOWFALL
MEANS THAT MUCH OF THE CWA IS TRANSITIONING OUT OF WARNING
CRITERIA. GIVEN WARNING ONLY GOES THROUGH THE LATE MORNING AND
REDUCED VISIBILITY PLUS BLOWING AND DRIFTING STILL ONGOING...WILL
LEAVE FOR DAYSHIFT TO DOWNGRADE OR CANCEL. AS FOR SUGGESTIONS OF A
FOLLOWON ADVISORY...SNOW SHOWERS WILL CONTINUE THROUGHOUT THE
DAY...HOWEVER UPSTREAM OBS ARE NOT INDICATING ANYTHING
PARTICULARLY INTENSE SO ADDITIONAL ACCUMULATIONS WILL BE ON THE
RELATIVELY LIGHT SIDE. WINDS WILL ALSO CONTINUE TO DROP OFF AS
SYSTEM SLOWLY MOVES AWAY AND WEAKENS.
LITTLE THERMAL ADVECTION EXPECTED BETWEEN NOW THROUGH THE END OF
THE PERIOD...THUS TEMPERATURES TODAY EXPECTED TO MOVE
LITTLE...FOLLOWED BY A SLOW COOLING TREND AS MORE FAVORABLE
RADIATIONAL CONDITIONS TAKE OVER. WINDS WILL STAY UP ENOUGH FOR
MIXING TONIGHT...BUT BY MONDAY...REGION WILL EXPERIENCE IDEAL
RADIATIONAL CONDITIONS WITH SURFACE HIGH NEARLY OVERHEAD AND NEARLY
A FOOT OF SNOW NOW INSULATING THE GROUND.
.LONG TERM...MONDAY NIGHT THROUGH FRIDAY
THE OVERALL PATTERN PREDICTED BY THE 00Z DETERMINISTIC AND
ENSEMBLE MODELS SUGGESTS A POSITIVE PNA PATTERN OVER THE
CONUS...WITH A WEST COAST RIDGE...AND CENTRAL/EAST CONUS TROF.
THIS PATTERN IS NOT TYPICALLY A WET PATTERN FOR THE REGION.
ALTHOUGH THAT SAID A COUPLE OF CLIPPER-LIKE SYSTEMS ARE EXPECTED TO
PASS THROUGH THE NORTHERN PLAINS DURING THE LONG TERM. GFS BUFR
SOUNDINGS INDICATE THAT CHANCES FOR MEASURABLE PCPN ARE NOT
PARTICULARLY HIGH WITH THESE SYSTEMS...SO WILL KEEP DRY FORECAST
IN PLACE. MEANWHILE TEMPERATURES THROUGH THE FORECAST PERIOD
SHOULD FAVOR BELOW NORMAL READINGS. VAST/DEEP SNOW FIELD...AND
UPPER LEVEL TROFFING SHOULD ENHANCE THE CHANCES FOR BELOW NORMAL
TEMPERATURES.
&&
.AVIATION...
EXPECT A CONTINUATION OF PRIMARILY IFR VSBYS AT ALL TERMINALS TODAY
DUE TO A COMBINATION OF FALLING/BLOWING SNOW. N/NWLY WINDS OF 15
TO 30 KTS WILL PERSIST THROUGH AT LEAST 00Z SUN...THEN SLOWLY
SUBSIDE OVERNIGHT. CIGS EXPECTED TO BE QUITE VARIABLE...RANGING
FROM VFR TO IFR...DEPENDING ON PERIODS OF LIGHT SNOW. CONDITIONS
WILL CONTINUE TO IMPROVE OVERNIGHT...WITH ANY LIGHT SNOW TAPERING
TO FLURRIES BY SUNDAY MORNING.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR BROWN-
BUFFALO-CAMPBELL-CLARK-CODINGTON-DAY-DEUEL-EDMUNDS-FAULK-
GRANT-HAMLIN-HAND-HUGHES-HYDE-MARSHALL-MCPHERSON-POTTER-
ROBERTS-SPINK-SULLY-WALWORTH.
BLIZZARD WARNING UNTIL 6 PM CST /5 PM MST/ THIS EVENING FOR
CORSON-DEWEY-JONES-LYMAN-STANLEY.
MN...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR BIG
STONE-TRAVERSE.
&&
$$
UPDATE...TMT
SHORT TERM...CONNELLY
LONG TERM...TDK
AVIATION...FOWLE
WEATHER.GOV/ABERDEEN
