Gale Warning 1009, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
1215 PM AKST MON DEC 28 2009

.ANALYSIS AND UPPER LEVELS...UPPER RIDGE IS BUILDING NORTHWESTWARD
ACROSS ALASKA AS SHORT-WAVE TROUGH EXTENDING FROM A VERTICALLY
STACKED LOW SOUTH OF THE EASTERN ALEUTIANS DIGS EASTWARD TOWARD
THE NORTHWEST U.S. THIS WILL EVENTUALLY LEAD TO A CUT-OFF HIGH
OVER ALASKA. AN OCCLUDED FRONT EXTENDS ACROSS THE EASTERN BERING
SOUTHEASTWARD ACROSS THE ALASKA PENINSULA TO KODIAK ISLAND. A
STRONG LOW LEVEL SOUTHEASTERLY JET CONTINUES TO PUMP WARM AIR
ACROSS THIS REGION...RESULTING IN AREAS OF RAIN...EXCEPT FOR
FREEZING RAIN NORTH AND WEST OF BETHEL WHERE A SHALLOW NEAR
SURFACE LAYER REMAINS BELOW FREEZING. THE POPULATION CENTERS
OF BRISTOL BAY AND THE KUSKOKWIM DELTA ARE EXPERIENCING STRONG
DOWNSLOPE DRYING...SO CEILINGS ARE HIGH...ALTHOUGH THERE IS QUITE
A BIT IF LOW LEVEL WIND SHEAR. THE SOUTHEASTERLY JET AND RIDING
TO THE NORTH ARE STEERING THE STORM AND ASSOCIATED PRECIP
NORTHWESTWARD ACROSS THE EASTERN ALEUTIANS AND CENTRAL BERING.

.MODEL DISCUSSION...MODELS INITIALIZED WELL AND ARE IN FAIR
AGREEMENT THROUGH TUESDAY NIGHT...BU THEN DIVERGE IN TRACK OF
DISSIPATING LOW NORTHWESTWARD ACROSS THE BERING AS WELL AS NEXT
SYSTEM APPROACHING THE WESTERN ALEUTIANS TUESDAY NIGHT INTO
WEDNESDAY. GFS SHOWS GOOD RUN-TO-RUN CONSISTENCY WITH THESE
SYSTEMS AND 12Z EC SHOWS A SIMILAR SOLUTION...SO WILL STICK
WITH THE GFS.

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...THE NEARLY STATIONARY FRONT SOUTH OF KODIAK
ISLAND WILL MAINTAIN RAIN AND WIND IN KODIAK THROUGH WEDNESDAY
WITH IMPROVING CONDITIONS AFTER THAT AS THE FRONT FALLS APART.
ELSEWHERE ACROSS SOUTHCENTRAL HIGH PRESSURE WILL PROVIDE DRY
CONDITIONS. THERE IS GOOD POTENTIAL FOR AREAS OF FOG FOR THE
NEXT FEW DAYS WITH LIGHT WINDS AND FAIRLY STEEP SURFACE-BASED
INVERSIONS IN PLACE. CIRRUS CLOUDS ASSOCIATED WITH THE SYSTEM
TO THE SOUTHWEST ARE QUITE EXTENSIVE ACROSS SOUTHCENTRAL AND WILL
LIMIT FOG FORMATION INITIALLY...BUT THEY WILL DIMINISH WITH TIME
AS THE RIDGE BECOMES MORE DOMINANT.

SOUTHWEST ALASKA...WITH THE OCCLUDED FRONT REMAINING NEARLY
STATIONARY JUST OFFSHORE OF THE SOUTHWEST COASTLINE EXPECT
PERSISTENT CONDITIONS THROUGH TUESDAY...WITH WARM
TEMPERATURES...GUSTY WINDS...AND AREAS OF RAIN. TEMPERATURES HAVE
BEEN SLOWLY WARMING TO FREEZING OR ABOVE ACROSS THE KUSKOKWIM DELTA
COAST WHERE PRECIP IS FALLING...ALTHOUGH THE REGION NORTH OF TOKSOOK
BAY UP TO HOOPER BAY REMAIN BELOW FREEZING. EXPECT TEMPERATURES TO
HOVER AROUND THIS MARK THROUGH TUESDAY...SO THE THREAT FOR FREEZING
RAIN WILL PERSIST AND WILL NEED TO CONSIDER EXTENDING THE FREEZING
RAIN ADVISORY WHICH IS CURRENTLY IN EFFECT FOR THIS REGION. THE
FRONT WILL FINALLY DISSIPATE TUESDAY NIGHT AND WEDNESDAY AND HIGH
PRESSURE WILL BUILD IN...BRINGING COOLER TEMPERATURES AND LIGHTER
WINDS.

BERING SEA/ALEUTIANS...THE STORM SOUTH OF THE EASTERN ALEUTIANS
WILL SLOWLY WEAKEN AS IT TRACKS NORTWESTWARD ACROSS THE BERING
TUESDAY AND WEDNESDAY...WITH COOLER AND CALMER CONDITIONS IN ITS
WAKE. MEANWHILE...A STORM OVER THE FAR NORTHWEST PACIFIC WILL
TRACK DUE EASTWARD TO SOUTH OF THE WESTERN ALEUTIANS BY WEDNESDAY.
RIDGING OUT AHEAD OF IT LOOKS LIKE IT WILL PREVENT THIS SYSTEM
FROM MAKING MUCH EASTWARD PROGRESSION BEYOND THAT POINT.

.LONG TERM FORECAST...ALTHOUGH THE GFS AND ECMWF MEDIUM RANGE
SOLUTIONS DONT LINE UP PERFECTLY...THEY NOW BOTH DEPICT THE SAME
GENERAL LONG-WAVE EVOLUTION...WITH THE UPPER RIDGE RETROGRADING
WESTWARD TOWARD THE CHUKCHI SEA WEDNESDAY AND THURSDAY AND SETTING
UP SHOP OVER THE BERING AFTER THAT. THIS WILL ALLOW A SHORT-WAVE
TO DROP SOUTHWARD ACROSS MAINLAND LATE IN THE WEEK AND USHER ARCTIC
AIR SOUTHWARD. BASED ON THE LATEST MODEL RUNS IT DOES LOOK LIKE
THE COLDEST AIR WILL MOVE INTO CANADA...BUT EVEN WITH THIS THE
AIRMASS FORECAST TO MOVE OVER MAINLAND ALASKA LOOKS COLD ENOUGH
TO PRODUCE BELOW NORMAL TEMPERATURES ACROSS THE EASTERN HALF OF
THE STATE BY NEXT WEEKEND. ALONG WITH THIS COMES THE LIKELIHOOD
OF A NORTHERLY WIND EVENT AS THE AIR SINKS OFF THE COASTAL RANGE
INTO THE GULF OF ALASKA. SO...IN SUMMARY...THERE IS ABOVE AVERAGE
CONFIDENCE IN COLDER AND DRIER AIR MOVING IN LATE THIS WEEK WITH
STRONG NORTHERLIES DEVELOPING IN THE USUAL LOCATIONS.

OUT WEST...THE RIDGE WILL CONFINE MOST OF THE UNSETTLED WEATHER
TO THE CENTRAL TO WESTERN ALEUTIANS AND WESTERN BERING AS STORMS
CONTINUE TO TRACK OUT OF ASIA AND ACROSS THE NORTH PACIFIC.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE WARNING 130 132 138 150 160 180.
FIRE WEATHER...NONE.

SEB DEC 09