Small Craft Advisory 342, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT THU APR 18 2013

.MODEL DISCUSSION...
NUMERICAL GUIDANCE IN FAIRLY GOOD AGREEMENT THROUGH 60 HOURS THEN
DIVERGE A BIT ON LOCATION/TIMING OF A LOW MOVING IN THE GULF. THE
ECMWF AND GEM GLOBAL BRING THE LOW IN FASTER AND HAVE IT MOVING
OVER KODIAK ISLAND ON SUNDAY...WHILE THE GFS AND UKMET ARE SLOWER
AND FURTHER EAST...WITH THE UKMET THE SLOWEST. THE AFTERNOON
FORECAST IS A BIT OF A COMPROMISE...BUT IS CLOSER TO THE ECMWF/GEM
SOLUTION.

.ANALYSIS AND UPPER LEVELS...
THERE IS AN UPPER LEVEL LOW CENTERED OVER THE SOUTHWEST YUKON
TERRITORY WITH CYCLONIC FLOW OVER MOST OF ALASKA...THE EXCEPTION
BEING A RIDGE ALONG THE WEST COAST OF ALASKA THAT EXTENDS INTO THE
NORTHERN BERING SEA. THERE IS A LARGE COMPLEX UPPER LOW CENTERED
SOUTH OF THE ALEUTIANS WITH A FRONT EXTENDING INTO THE SOUTHERN
BERING SEA UP TO ABOUT THE PRIBILOFS. A SHORT-WAVE TROUGH ASSOCIATED
WITH THE YUKON LOW IS OVER CENTRAL ALASKA AND MOVING SOUTH.

.SHORT TERM FORECAST...
FOR SOUTH CENTRAL AND SOUTHWEST ALASKA...THE SHORT-WAVE TROUGH OVER
CENTRAL ALASKA WILL MOVE SOUTH THROUGH FRIDAY AND THEN CLOSE OFF
OVER KODIAK ISLAND FRIDAY NIGHT. THE WEST COAST/BERING HIGH WILL
PUSH INLAND BEHIND THIS TROUGH AND EXPAND EASTWARD THROUGH SATURDAY.
THE LOW NEAR KODIAK ISLAND FRIDAY NIGHT WILL THEN CUT OFF COMPLETELY
FROM THE FLOW JUST SOUTHWEST OF KODIAK ISLAND AND THEN MOVE
NORTHEAST SATURDAY NIGHT AND SUNDAY. THE RIDGE WILL CONTINUE TO MOVE
EAST...CENTERED OVER SOUTH CENTRAL ALASKA ON SATURDAY AND INTO THE
PANHANDLE ON SUNDAY. CONDITIONS WILL REMAIN DRY OVER SOUTHERN ALASKA
THROUGH SATURDAY AND THEN CHANCES OF PRECIPITATION WILL INCREASE
SATURDAY NIGHT AND SUNDAY AS THE LOW MOVES NORTHEAST.

FOR THE ALEUTIANS AND BERING SEA...THE ALEUTIAN LOW COMPLEX WILL
SLOWLY DRIFT SOUTHEAST THROUGH FRIDAY AND NO LONGER BE A WEATHER
FACTOR IN THE AREA ON SATURDAY. AS THAT LOW EXITS AND THE WEST
COAST/BERING HIGH MOVES EAST...THIS WILL ALLOW NORTHERLY FLOW TO
DEVELOP OVER THE CENTRAL BERING SEA AND ALEUTIANS...AND BRING A FAST
MOVING LOW THROUGH THAT AREA SATURDAY INTO SUNDAY. OVER THE WESTERN
BERING SEA A RIDGE WILL BUILD FRIDAY NIGHT AND SATURDAY...AND MOVE
EAST INTO THE CENTRAL BERING ON SUNDAY AHEAD OF A DEEP LOW MOVING IN
FROM KAMCHATKA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.

LUDWIG APR 13