Gale Warning 256, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
1210 PM AKST SUN MAR 3 2013

.ANALYSIS AND UPPER LEVELS...
THE WEATHER PATTERN IS TRANSITIONING FROM PROGRESSIVE FLOW WITH A
FAIRLY HIGH ZONAL INDEX TO A LONGWAVE TROUGH OVER THE BERING SEA WITH
RIDGING OVER THE EASTERN GULF OF ALASKA. THERE IS CURRENTLY A
WEAKENING VERTICALLY STACKED LOW SOUTH OF THE ALASKA PENINSULA WITH
AN ASSOCIATED FRONT PRIMARILY AFFECTING KODIAK ISLAND WITH WIND AND A
RAIN/SNOW MIX. THE MAIN CIRCULATION OF THIS LOW IS MOVING TO THE
SOUTHEAST AND OUT INTO THE PACIFIC AS A NEGATIVELY TILTED RIDGE
BUILDS NORTHWARD ALONG THE COAST OF BRITISH COLUMBIA AND INTO THE
GULF OF ALASKA. WIDESPREAD MODERATE EASTERLY FLOW ACROSS MOST OF THE
GULF REGION IS FOCUSING PRECIPITATION ALONG THE COASTLINES WITH THE
DOWN-SLOPE EFFECT IN FULL FORCE INLAND. OUT WEST...ANOTHER LARGE AND
STRONG STORM IS LOCATED WEST OF ALEUTIAN ISLANDS...WITH AN ASSOCIATED
FRONT AHEAD OF THE STORM THAT IS MOVING INTO THE CENTRAL ALEUTIANS
WITH GALE FORCE WINDS.

.MODEL DISCUSSION...
THE MODELS ARE IN EXCELLENT SYNOPTIC AGREEMENT...WHICH IS NOT UNUSUAL
FOR HIGHLY AMPLIFIED WEATHER PATTERNS WHERE THE MAJOR FEATURES TEND
TO EVOLVE SLOWER THAN FAST ZONAL FLOW. THE FRONT AFFECTING KODIAK
ISLAND WILL MAKE MINIMAL NORTHWARD PROGRESS THROUGH THIS EVENING
BEFORE BEGINNING A RETREAT SOUTHWARD AND EVENTUALLY OUT INTO THE
PACIFIC. MOST OF THE MODELS ARE SUGGESTING A WEAK PIECE OF THE
CIRCULATION WILL BREAK OFF AND MOVE WESTWARD THROUGH BRISTOL
BAY...LIKELY KEEPING CLOUDS AND GUSTY WINDS IN THAT AREA THROUGH
TONIGHT...EVEN AS THE MAIN LOW MOVES WELL SOUTHWARD. OUT WEST...THE
LARGE LOW WEST OF SHEMYA HAS BEGUN TO FILL AND WILL SLIDE NORTHWARD
OVER THE NEXT 48 HOURS. THE ASSOCIATED FRONT OVER THE CENTRAL
ALEUTIANS WILL SLOWLY PROGRESS EASTWARD AND REACH THE COAST OF THE
SOUTHWEST MAINLAND IN VERY WEAKENED FORM BY TUESDAY MORNING. THE NAM
WAS THE MODEL OF CHOICE OF THE EASTERN DOMAIN FOR ITS ABILITY TO
CAPTURE LOCAL CHANNELING OF THE WINDS. OUT WEST...THE NAM WAS A
SLIGHT OUTLIER BEING TOO SLOW TO ADVANCE THE BERING SEA FRONT. AS A
RESULT...THE FASTER GFS/EC POSITION WAS PREFERRED WEST OF THE ALASKA
RANGE.

.SHORT TERM FORECAST...
THE ALASKA AREA WILL BE IMPACTED BY ONE PRIMARY SYSTEM OVER THE NEXT
SEVERAL DAYS. WITH THE FRONT IN THE GULF MOVING AWAY TO THE
SOUTHEAST...GRADUALLY INCREASING AMOUNTS OF SUNSHINE ARE LIKELY
ACROSS MUCH OF THE SOUTHERN MAINLAND THROUGH TUESDAY WITH ABOVE
AVERAGE TEMPERATURES. MEANWHILE...THE WEAKENING FRONT IN THE BERING
SEA WILL BRING A BRIEF PERIOD OF RAIN AND SNOW TO THE MAINLAND COAST
BY TUESDAY...MOVING INTO SOUTHCENTRAL ON WEDNESDAY. THE FRONT WILL BE
ACCOMPANIED BY GUSTY WINDS BUT NO BLOWING SNOW ISSUES ARE EXPECTED
WITH TEMPERATURES RISING TO NEAR FREEZING IN MOST AREAS.

.LONG TERM FORECAST...
TEMPERATURES REMAIN MILD WITH RELATIVELY BENIGN CONDITIONS (BY ALASKA
STANDARDS) THROUGH MIDWEEK. CONFIDENCE IS INCREASING THAT BY THURSDAY
A MUCH MORE SIGNIFICANT LOW WILL MOVE UP FROM THE PACIFIC TOWARD
KODIAK ISLAND AND SOUTHWEST ALASKA. THIS STORM BEARS MUCH WATCHING AS
IT LOOKS LIKE IT HAS THE POTENTIAL TO DEVELOP WARNING LEVEL WINDS IN
SOME FAVORED AREAS. STAY TUNED TO THE LATEST FORECAST FOR UPDATES IN
THE COMING DAYS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 130 155 170 172 175 176 185
FIRE WEATHER...NONE

AMD MAR 13