Gale Warning 768, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 AM AKDT THU OCT 27 2011

.MODEL DISCUSSION...
MODELS IN REASONABLY GOOD AGREEMENT. 00Z GFS HAS COME IN LINE WITH
YESTERDAYS 12Z ECMWF. GFS WAS PREFERRED THROUGH 84 HOURS AND A GFS
HPC BLEND BEYOND. NAM HAS GOOD HANDLE ON GAP WINDS IN THE FIRST 48
HOURS.

.ANALYSIS...
SURFACE PATTERN IS HIGHLY PROGRESSIVE AS IS TYPICAL OF THIS TYPE OF
YEAR. 991 MB LOW NEAR THE SOUTHERN TIP OF KODIAK WILL DRIFT SLOWLY
EASTWARD TODAY AND MERGE WITH A LARGE 968 MB LOW IN THE SOUTHEASTERN
GULF OF ALASKA LATE TONIGHT. THE COMBINED LOW THEN MOVES NORTH AND
DISSIPATES OVER THE NORTHERN PANHANDLE LATE FRIDAY NIGHT.
A 977 MB LOW IN THE FAR WESTERN BERING SEA WILL PRESS EASTWARD
ACROSS THE SOUTHERN BERING SEA TODAY...PASS JUST NORTH OF THE
EASTERN ALEUTIANS TONIGHT...CROSS OVER THE ALASKA PENINSULA ON
FRIDAY...AND MOVE INTO THE WESTERN GULF OF ALASKA FRIDAY NIGHT.

.SHORT TERM FORECAST...
MOST OF SOUTHCENTRAL ALASKA WILL REMAIN UNDER A LEAST MILD WARM
ADVECTION THROUGH 60 HOURS. SO WHILE AREAS SOUTH AND EAST OF
ANCHORAGE WILL LIKELY EXPERIENCE AN EXTENDED PERIOD OF
PRECIPITATION...MOST OF THAT PRECIP WILL BE FALLING AS RAIN. ONLY
THE COPPER RIVER BASIN AND HIGHER ELEVATIONS OF THE KENAI AND
CHUGACH MOUNTAINS ARE LIKELY TO EXPERIENCE ANY MEASURABLE SNOWFALL.
A WEAK DISTURBANCE ALOFT WILL TRIGGER LIGHT SNOW OVER SOUTHWEST
ALASKA TODAY...BUT FEATURE IS MUCH WEAKER THAN ORIGINALLY EXPECTED.
CANCELED SNOW ADVISORY FOR BRISTOL BAY AND LOWER KUSKOKWIM VALLEY.
SNOW WILL BE LIMITED TO INLAND AREAS...AND NO MORE THAN 3 INCHES
ACCUMULATION IS BEING FORECAST...WITH THE HIGHEST AMOUNTS ALONG THE
ALASKA RANGE.
SYSTEM OUT WEST IS ALREADY SPREADING SOUTH TO SOUTHWESTERLY GALES...
AS WELL AS RAIN AND RAIN SHOWERS AS FAR EAST AS SEGUAM ISLAND. RAIN
WILL SPREAD INTO THE PRIBILOFS AND EASTERN ALEUTIANS TODAY AND
ACROSS THE ALASKA PENINSULA TONIGHT. WINDS SHIFT TO THE NORTHWEST
ACROSS THE CENTRAL AND WESTERN ALEUTIANS TONIGHT. GUSTY NORTHWEST
WINDS MAY EXCEED 75 MPH TONIGHT WITH AID FROM THE JET ALOFT. WATCH
ISSUED FOR CENTRAL ALEUTIANS.

.UPPER LEVELS AND LONG TERM FORECAST...
UPPER LEVEL PATTER WILL REMAIN HIGHLY PROGRESSIVE AS IS TYPICAL OF
THIS TYPE OF YEAR. UPPER LEVEL WAVES MOVING OUT OF EASTERN RUSSIA
INTO THE BERING SEA WILL CONTINUE TO USHER LOW PRESSURE SYSTEMS INTO
THE BERING...ACROSS THE ALASKA PENINSULA...AND INTO THE WESTERN GULF
OF ALASKA. BOTH THE MAINLAND AND THE ISLANDS WILL CONTINUE TO
EXPERIENCE PERIODS OF UNSETTLED WEATHER BUFFERED BY BRIEF PERIODS OF
QUIET BETWEEN SYSTEMS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HWW ZONE 187 FOR TONIGHT.
MARINE...GALE  130 179 185 412
         STORM 172 175 176 411 413
FIRE WEATHER...NONE.

ASB OCT 11