Small Craft Advisory 551, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 PM AKDT TUE SEP 6 2011

.ANALYSIS AND UPPER LEVELS...
THE MAIN UPPER LOW NEAR KODIAK ISLAND HAS WEAKENED SINCE MONDAY AND
CONTINUES TO DRIFT WEST TOWARD BRISTOL BAY. THE UPPER RIDGE REMAINS
OVER THE NORTHWEST PACIFIC AND KAMCHATKA PENINSULA AND A SECOND RIDGE
OVER WESTERN CANADA SLOWLY MOVING EAST. THE SURFACE LOW REMAIN
VERTICALLY STACK BENEATH THE MAIN UPPER CENTER AND CONTINUES TO
WEAKEN SLOWLY. A SURFACE RIDGE IS BUILDING OVER SOUTHEAST ALASKA AND
ALONG THE CENTRAL GULF COAST.

.MODEL DISCUSSION...
MODELS ARE IN GOOD AGREEMENT THROUGH THURSDAY AFTERNOON BUT THE
SOLUTIONS BEGIN TO DIVERGE OVER THE GULF OF ALASKA FRIDAY AFTERNOON.
NAM BRINGS A CLOSED LOW INTO GULF WHILE THE GFS KEEPS IT AN OPEN
WAVE. AT THIS TIME...WE ARE CONVINCED THE GFS HAS THE BETTER
SOLUTION.

.SHORT TERM FORECAST...
THE SURFACE LOW NEAR KODIAK ISLAND WILL MOVE WEST INTO EASTERN
BRISTOL BAY TONIGHT THEN TURN SOUTH TO NEAR CHIGNIK WEDNESDAY NIGHT
AND INTO THE CENTRAL NORTH PACIFIC THURSDAY. A SURFACE TROUGH WILL
REMAIN OVER THE CENTRAL INTERIOR AND SOUTHWEST ALASKA THROUGH
THURSDAY. THE RIDGE ALONG THE CENTRAL GULF COAST WILL CONTINUE TO
BUILD THROUGH THURSDAY. THE RIDGE WEST OF THE BERING SEA WILL MOVE
INTO THE CENTRAL BERING THURSDAY AFTERNOON.

.SOUTHCENTRAL ALASKA AND THE GULF...SOUTH TO SOUTHEAST WIND OVER THE
GULF WILL SLOWLY DIMINISH THROUGH THURSDAY. RAIN OVER PRINCE WILLIAM
SOUND, EASTERN KENAI PENINSULA AND WESTERN SUSITNA VALLEY WILL
CONTINUE THROUGH WEDNESDAY NIGHT THEN DIMINISH TO SHOWERS THURSDAY.
STRONG WINDS ALONG THE COAST WILL CONTINUE TO WEAK THROUGH WEDNESDAY
NIGHT.

.SOUTHWEST ALASKA...CLOUDS WILL BE INCREASING THROUGHOUT THE AREA
WITH SCATTERED SHOWERS DEVELOPING OVER BRISTOL BAY AND THE KUSKOKWIM
VALLEY TONIGHT AND SPREAD INTO THE KUSKOKWIM DELTA WEDNESDAY MORNING.
THE SHOWERS WILL BECOME MORE FREQUENT WEDNESDAY AFTERNOON THROUGH
THURSDAY. STRONG WINDS ALONG THE COAST WILL PERSIST THROUGH WEDNESDAY
NIGHT THEN BEGIN TO DIMINISH THURSDAY.

.BERING SEA AND ALEUTIANS...NORTH WINDS WILL DIMINISH FROM THE WEST
THROUGH THURSDAY AS THE RIDGE MOVES INTO THE CENTRAL BERING.

.LONG TERM FORECAST...
THE TROUGH OVER WESTERN ALASKA WILL WEAKEN AS THE RIDGE OVER THE
BERING MOVES INTO SOUTHWEST ALASKA FRIDAY. A WEATHER FRONT NEAR THE
KAMCHATKA PENINSULA THURSDAY NIGHT WILL MOVE INTO THE CENTRAL BERING
FRIDAY AND EASTERN BERING SATURDAY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 120 155 160 165 170 179 180 185
FIRE WEATHER...NONE.

NM SEP 11