FXAK68 PAFC 080021 CCA
AFDAFC

AREA FORECAST DISCUSSION 
SOUTHCENTRAL AND SOUTHWEST ALASKA
1255 PM AKST MON DEC 7 2009

CORRECTION TO WARNING AND MARINE TABLE

.ANALYSIS AND UPPER LEVELS...
THE OVERALL PATTERN REMAINS UNCHANGED FROM THE PREVIOUS SEVERAL
DAYS...A HIGH AMPLITUDE RIDGE IS IN PLACE OVER THE GULF AND MAINLAND
ALASKA WHILE A DEEP TROUGH PERSISTS OVER THE BERING SEA AND NORTH
PACIFIC. THE JET STREAM IS FLOWING NORTH-NORTHWEST BETWEEN THE TWO
FEATURES WITH A POTENT SHORTWAVE EMBEDDED WITHIN THE FLOW...CURRENTLY
CROSSING THE ALASKA PENINSULA. A 150 KT JET CORE IS ASSOCIATED WITH
THIS IMPULSE. 

AT THE SURFACE...HIGH PRESSURE IS BUILDING OVER THE GULF AND
SOUTHCENTRAL ALASKA. THE MID AND UPPER LEVEL CLOUDS HAVE SLOWLY
ERODED RESULTING IN MOSTLY SUNNY SKIES OVER MOST OF SOUTHCENTRAL AND
THE SOUTHWEST MAINLAND. THE LARGE QUASI-BAROTROPIC LOW CONTINUES TO
WEAKEN AS IT DRIFTS NORTHWEST ACROSS THE CENTRAL ALEUTIANS INTO THE
SOUTHERN BERING SEA...AND EVENTUALLY INTO EASTERN SIBERIA BY
WEDNESDAY.

.MODEL DISCUSSION...FORECAST CONFIDENCE REMAINS HIGH AS THE MAJOR
MODELS EXCLUDING THE NAM ARE IN EXCELLENT AGREEMENT THROUGH MID WEEK.
SOME SYNOPTIC DIFFERENCES IN THE BERING SEA ARISE ON WEDNESDAY
ALTHOUGH IT HAS LITTLE IMPACT ON THE FORECAST. ONLY MINOR ADJUSTMENTS
WERE MADE...MAINLY A GENTLE NUDGE TOWARD THE LATEST GFS IN THE MEDIUM
RANGE.

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...
AS PREVIOUSLY MENTIONED THE MID AND UPPER LEVEL CLOUDS HAVE DECREASED
ACROSS THE REGION WHICH HELPED LEAD TO SOME FOG FORMING OVER THE
INLET OVERNIGHT AND THIS MORNING. THE CURRENT THINKING IS THAT THE
FOG WILL DEVELOP AGAIN OVERNIGHT...BUT THIS TIME MAY BE A BIT EARLIER
AND MAY IMPACT A LARGER AREA. THIS IS ALL A RESULT OF THE HIGH
PRESSURE SETTLING OVER SOUTHCENTRAL ALASKA AND THE IMPRESSIVE LOW
LEVEL INVERSION. TEMPERATURES IN THE ANCHORAGE BOWL CURRENTLY RANGE
FROM 8 DEGREES AT THE CAMPBELL CREEK SCIENCE CENTER TO NEAR 40
DEGREES AT THE UPPER HILLSIDE. THIS PATTERN WILL PERSIST THROUGH THE
WEEK WITH FOG AND LOW CLOUDS EXPECTED OVERNIGHT AND DURING THE EARLY
MORNING HOURS BUT OTHERWISE MOSTLY CLEAR SKIES PREVAILING.
TEMPERATURES WILL VARY WILDLY DEPENDING ON THE ELEVATION.

MODELS HAVE BACKED OFF SIGNIFICANTLY FROM THE COLD AIR INTRUSION THAT
WAS BEING ADVERTISED FOR THE WEEKEND. A COLD ARCTIC AIRMASS WILL
BUILD OVER THE YUKON TERRITORY BUT IS NOT EXPECTED TO SPILL INTO
SOUTHCENTRAL UNTIL EARLY NEXT WEEK AT THE EARLIEST.

SOUTHWEST INTERIOR...SOUTHEAST FLOW ACROSS THE REGION IS DIMINISHING.
THE STRONGEST WINDS ARE NOW LIMITED TO THE ALASKA PENINSULA AND THE
WESTERN CAPES ASSOCIATED WITH THE AFOREMENTIONED UPPER LEVEL IMPULSE.
BREEZY CONDITIONS WILL PERSIST THROUGH MID WEEK IN THESE
AREAS...ALTHOUGH NO WHERE NEAR AS STRONG AS THE WINDS HAVE BEEN THIS
PAST WEEKEND. MOSTLY CLEAR SKIES WILL PREVAIL AS THE UPPER LEVEL
RIDGE BUILDS OVER THE REGION THROUGH THE REMAINDER OF THE WEEK.  

BERING SEA/ALEUTIANS...THE ACTIVE WEATHER AND MOST OF OUR FOCUS
REMAINS OUT WEST WHERE HIGH WIND WARNINGS HAVE BEEN POSTED FOR THE
EASTERN ALEUTIANS AND PRIBILOF ISLANDS. THIS LAST PUSH OF STORM FORCE
WINDS AND HURRICANE FORCE GUSTS ASSOCIATED WITH THE UPPER LEVEL WAVE
WILL SPREAD ACROSS THE NORTHERN BERING SEA OVER NIGHT AND DIMINISH
TUESDAY. MUCH MORE TRANQUIL WEATHER WILL PERSIST THROUGH MIDWEEK WHEN
A FRONTAL BOUNDARY SETS UP ACROSS THE EASTERN ALEUTIANS...BRINGING A
RETURN OF GALE FORCE WINDS TO THE REGION. WHILE THE LONGWAVE PATTERN
IS EXPECTED TO REMAIN UNCHANGED...BROAD SOUTHEASTERLY WINDS WILL
PERSIST THROUGH THE REMAINDER OF THE WEEK ACROSS THE BERING SEA WITH
ABOVE AVERAGE TEMPERATURES.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WARNING 185 AND 195. 
MARINE...STORM WARNING...170 171 179 185 
         GALE WARNING...155 160 165 176 180.
FIRE WEATHER...NONE.

AB DEC 09