Gale Warning 763, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM AKDT MON OCT 26 2009

.MODEL DISCUSSION...
THE MODELS APPEAR TO BE IN FAIR AGREEMENT OVER THE GULF AND
SOUTHCENTRAL ALASKA AND MUCH BETTER AGREEMENT OVER THE BERING SEA
THROUGH WEDNESDAY NIGHT. THE GFS MODEL IS MOVING NEXT LOW INTO THE
GULF A LITTLE FASTER THAN THE EUROPEAN OR NAM MODELS. ALL THE MODELS
ARE HANDLING THE NEXT LARGE STORM MOVING TOWARD THE WESTERN ALEUTIANS
ABOUT THE SAME. THE NAM MODEL IS THE MODEL OF CHOICE THROUGH TUESDAY
AFTERNOON BEFORE SWITCHING TO THE EUROPEAN MODEL THROUGH WEDNESDAY
NIGHT.

.ANALYSIS AND UPPER LEVELS...
UPPER LEVELS...AN UPPER LOW NEAR THE PRIBILOFS EXTENDS A TROUGH INTO
SOUTHWEST ALASKA AND THE KENAI PENINSULA AND IS PRODUCING SCATTERED
RAIN AND SNOW SHOWERS OVER THE SOUTHWEST INTERIOR, KENAI PENINSULA
AND PRINCE WILLIAM SOUND. A SHORT WAVE TROUGH OVER THE COPPER RIVER
BASIN HAD PRODUCED AREAS OF LIGHT SNOW TO THE REGION. AN UPPER RIDGE
IS BEGINNING TO BUILD OVER THE WESTERN BERING SEA.
AT THE SURFACE...A WEAKENING LOW NEAR THE SOUTHERN ALCAN BORDER
CONTINUES TO MOVE EAST INTO THE YUKON TERRITORY. A SECONDARY LOW HAS
FORMED OVER PRINCE WILLIAM SOUND UNDER THE UPPER TROUGH. A WEAK LOW
OVER THE EASTERN BERING SEA WILL DISSIPATE INTO A TROUGH TONIGHT.

.SHORT TERM FORECAST...
UPPER LEVELS...THE UPPER LOW NEAR THE PRIBILOFS WILL WEAKEN AS IT
MOVES INTO SOUTHWEST ALASKA TUESDAY NIGHT THEN WILL DISSIPATE OVER
THE COOK INLET WEDNESDAY AS A STRONGER LOW MOVES INTO THE GULF. THE
UPPER RIDGE BUILDING OVER THE WESTERN BERING WILL MOVE INTO THE
EASTERN BERING WEDNESDAY.

SOUTHCENTRAL ALASKA AND THE GULF...
THE WEAK LOW WILL REMAIN OVER PRINCE WILLIAM SOUND BEFORE DISSIPATING
TUESDAY EVENING. SCATTERED RAIN SHOWERS OVER THE ANCHORAGE BOWL,
MATANUSKA AND SUSITNA VALLEYS WILL BECOME SNOW SHOWERS LATE THIS
EVENING AND WILL PERSIST THROUGH WEDNESDAY. AREAS OF SNOW OVER THE
COPPER RIVER BASIN WILL BECOME SCATTERED SNOW SHOWERS AS THE UPPER
SHORT WAVE TROUGH MOVES NORTH OF THE ALASKA RANGE TONIGHT. SCATTERED
RAIN SHOWERS WILL REMAIN OVER PRINCE WILLIAM SOUND THROUGH WEDNESDAY.
RAIN AND GALE FORCE WINDS WILL MOVE INTO THE GULF TUESDAY NIGHT AND
WEDNESDAY AHEAD OF A NEW STORM SYSTEM APPROACHING FROM THE SOUTH.

SOUTHWEST ALASKA...
A WEAK RIDGE OF HIGH PRESSURE OVER THE KUSKOKWIM DELTA AND WESTERN
BRISTOL BAY WILL MOVE INTO THE INTERIOR SECTION TUESDAY BEFORE
DISSIPATING TUESDAY NIGHT. A RIDGE OVER THE WESTERN BERING SEA WILL
MOVE INTO THE EASTERN BERING AND THE WEST COAST OF ALASKA WEDNESDAY.
SCATTERED SNOW SHOWERS OVER THE KUSKOKWIM VALLEY AND BRISTOL BAY WILL
DIMINISH FROM THE WEST AS THE RIDGE MOVES INTO THE AREA. ISOLATED
SNOW SHOWERS WILL REMAIN MOSTLY ALONG THE ALEUTIAN RANGE THROUGH
WEDNESDAY. SKIES WILL BEGIN TO CLEAR ALONG THE COAST WEDNESDAY.

BERING SEA AND THE ALEUTIANS...ISOLATED SHOWERS WILL DIMINISH FROM
THE WEST AS RIDGE MOVES FROM THE WESTERN BERING INTO THE EASTERN
BERING WEDNESDAY. A NEW STORM SYSTEM NEAR JAPAN WILL MOVE TO ABOUT
100 MILES SOUTHWEST OF ATTU WEDNESDAY AFTERNOON. RAIN WITH GALE TO
STORM FORCE WINDS WILL MOVE INTO THE WESTERN ALEUTIANS TUESDAY NIGHT
AND INTO THE CENTRAL ALEUTIANS WEDNESDAY.

.LONG TERM FORECAST...
THE STORM OVER THE SOUTHERN GULF WEDNESDAY EVENING WILL MOVE
NORTHEAST AND WEAKEN OVER SOUTHEAST ALASKA THURSDAY. THE RAIN AND
WIND OFF THIS STORM WILL REMAIN MOSTLY OVER THE GULF. THE THE RIDGE
ALONG THE WEST COAST OF ALASKA WILL MOVE NORTHEAST AND FORM A HIGH
OVER NORTHERN ALASKA THURSDAY AND FRIDAY. THE CLEARING OVER WESTERN
ALASKA WILL ACROSS THE SOUTHERN MAINLAND BY THURSDAY. GUSTY NORTH
WINDS WILL DEVELOP THROUGH CHANNELED TERRAIN ALONG THE ALASKA RANGE
AND CHUGACH MOUNTAINS THURSDAY AND FRIDAY. THE STORM NEAR THE WESTERN
ALEUTIANS WILL TURN NORTH AND MOVE INTO THE NORTHWEST BERING BY
FRIDAY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...STORM 176
         GALE 175
FIRE WEATHER...NONE.

NM OCT 09