Small Craft Advisory 819, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM AKDT THU OCT 23 2008

.MODEL DISCUSSION...
MODELS ARE IN GOOD AGREEMENT THROUGH SATURDAY NIGHT THOUGH THERE IS
SOME DISAGREEMENT ON THE POSITION OF THE NEXT LOW MOVING TOWARD THE
GULF SATURDAY NIGHT. GFS IS THE PREFERRED MODEL THROUGH FRIDAY NIGHT
AND THE ECMWF HAS A BETTER SOLUTION FROM SATURDAY ONWARD.

.ANALYSIS AND UPPER LEVELS...
A UPPER TROUGH OVER THE LOWER YUKON VALLEY AND THE YUKON DELTA
CONTINUES TO MOVE SOUTHEAST. THE ATMOSPHERE OVER SOUTHWEST ALASKA
APPEARS TO BE FAIRLY DRY, SO THE UPPER DISTURBANCE IS ONLY PRODUCING
ISOLATED SHOWERS.

AT THE SURFACE...A STRONG TRIPLE POINT LOW DEVELOPED OVER THE WESTERN
GULF OF ALASKA OVERNIGHT AND IS CURRENTLY MOVING NORTHEAST. THE
ASSOCIATED WEATHER FRONT HAS MOVED ONSHORE ALONG THE CENTRAL GULF
COAST AND IS PUSHING INLAND. THE BULK OF THE SNOW HAS FALLEN OVER
PRINCE WILLIAM SOUND AND THE COPPER RIVER BASIN WITH SMALLER AMOUNTS
OVER ANCHORAGE, MATANUSKA VALLEY AND THE KENAI PENINSULA.

COLD ADVECTION ON THE BACKSIDE OF THE LOW HAS CREATED STRONG WINDS
ACROSS KODIAK ISLAND, KENAI PENINSULA AND THE LOWER COOK INLET.

A SURFACE LOW NEAR SHEMYA HAD PRODUCED BANDS OF SNOW SHOWERS OVER THE
WESTERN BERING.

.SHORT TERM FORECAST...
THE MAIN UPPER LOW WILL REMAIN OVER THE CENTRAL INTERIOR AND SLOWLY
DISSIPATE INTO A TROUGH BY FRIDAY NIGHT. THE UPPER TROUGH OVER
SOUTHWEST ALASKA WILL MOVE THROUGH SOUTHCENTRAL ALASKA LATE TONIGHT
AND FRIDAY.

SOUTHCENTRAL ALASKA AND THE GULF...THE SURFACE LOW OVER THE NORTHERN
GULF WILL MOVE ONSHORE NEAR CAPE YAKATAGA THIS EVENING AND INTO THE
YUKON TERRITORY FRIDAY AND CONTINUE TO MOVE EAST ACROSS NORTHERN
CANADA SATURDAY. AREA OF GUSTY NORTH TO NORTHWEST WINDS ALONG THE
BACKSIDE OF THE LOW WILL MOVE THROUGH SOUTHCENTRAL ALASKA AND THE
GULF TONIGHT AND SATURDAY. SNOW OVER THE COPPER RIVER BASIN WILL
CHANGE TO SNOW SHOWERS TONIGHT. ELSEWHERE ACROSS SOUTHCENTRAL ALASKA,
WIDELY SCATTERED SNOW SHOWERS ASSOCIATED WITH THE UPPER TROUGH WILL
PERSIST THROUGH FRIDAY.

A RIDGE OF HIGH PRESSURE WILL DEVELOP OVER SOUTHWEST ALASKA FRIDAY
MOVE THROUGH SOUTHCENTRAL ALASKA FRIDAY NIGHT AND SATURDAY.

A WARM FRONT WILL MOVE INTO THE WESTERN GULF FRIDAY NIGHT AND WILL
BRING SOME LIGHT SNOW INTO KODIAK ISLAND,THE SOUTHERN KENAI PENINSULA
AND PRINCE WILLIAM SOUND FRIDAY NIGHT AND SATURDAY.

SOUTHWEST MAINLAND...WIDELY SCATTERED SNOW SHOWERS ASSOCIATED WITH
THE UPPER TROUGH WILL MOVE THROUGH THE AREA TONIGHT. A WEAK SURFACE
LOW WILL OVER THE BERING SEA WILL MOVE INTO BRISTOL BAY FRIDAY NIGHT
THEN DISSIPATE NEAR KING SALMON SATURDAY. AREAS OF SNOW WILL MOVE
INTO THE IMMEDIATE BRISTOL BAY COAST AND THE ALASKA PENINSULA FRIDAY
NIGHT AND SATURDAY.

BERING SEA...A WEAK LOW JUST NORTH OF THE WESTERN ALEUTIANS WILL MOVE
EAST INTO BRISTOL BAY FRIDAY NIGHT. A COLD FRONT EXTENDING SOUTHWEST
OF THE LOW WILL MOVE THROUGH THE ALEUTIANS THROUGH FRIDAY NIGHT
DISSIPATE OVER THE ALASKA PENINSULA SATURDAY. AN AREA OF SNOW
ASSOCIATED WITH THE LOW AND THE FRONT WILL MOVE ACROSS THE SOUTHERN
BERING SEA AND ALEUTIANS THROUGH FRIDAY NIGHT.

.LONG TERM FORECAST...
ANOTHER LOW WILL MOVE INTO THE GULF SUNDAY AND DISSIPATED NEAR PRINCE
WILLIAM SOUND MONDAY AND MONDAY NIGHT. THE ASSOCIATED WEATHER FRONT
WILL MOVE ONSHORE ALONG THE CENTRAL GULF COAST SUNDAY. ANOTHER LOW IS
EXPECTED TO MOVE INTO THE BERING SEA MONDAY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...STORM...120, 130, 132.
         GALE...121, 125, 129, 138, 140, 150, 155, 160, 165, 170.
FIRE WEATHER...NONE.

NM OCT 08