Small Craft Advisory 288, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT SUN MAR 31 2013

.MODEL DISCUSSION...
THE NUMERICAL MODELS ARE IN FAIRLY GOOD AGREEMENT THROUGH 84 HOURS.
THIS IS PARTLY DUE TO THE HIGH AMPLITUDE UPPER LEVEL PATTERN...WHICH
IS A FAIRLY PREDICTABLE REGIME. THEREFORE THE FORECAST CONFIDENCE
IS HIGHER THAN NORMAL. SOME MINOR DIFFERENCES BEGIN TO ARISE WITH
THE LOCATION OF A LOW SOUTH OF THE ALEUTIANS AFTER ABOUT 60 HOURS
AND THE FORECAST AT THIS POINT LEANS TOWARD THE GFS AND ECMWF AND
AWAY FROM THE NAM.

.ANALYSIS AND UPPER LEVELS...
THERE IS A WEAK UPPER LEVEL LOW OVER THE NORTHWESTERN GULF OF ALASKA
WITH A WEAK TROUGH STRETCHING NORTH OVER CENTRAL AND EASTERN ALASKA.
THERE IS A RIDGE ALONG THE WEST COAST OF ALASKA THAT EXTENDS
NORTHWARD WELL INTO THE ARCTIC OCEAN. AN UPPER LEVEL TROUGH OVER THE
CENTRAL BERING SEA IS MOVING TO THE NORTH AND THIS IS ASSOCIATED
WITH A LARGE STEERING LOW OVER EASTERN SIBERIA.

.SHORT TERM FORECAST...
THE GENERAL STORY OVER THE NEXT FEW DAYS CONCERNS THE STUBBORN WEST
COAST RIDGE...WHICH IS VERY RELUCTANT TO MOVE. THEREFORE SYSTEMS
MOVING IN FROM FURTHER WEST ARE NOT ALLOWED TO REACH MAINLAND ALASKA
THROUGH THE MIDDLE OF THE WEEK. THE GULF LOW WILL MOVE TO THE EAST
OVER THE NEXT DAY AND MOVE INLAND OVER THE PANHANDLE MONDAY NIGHT.
UPPER LEVEL CYCLONIC FLOW WILL REMAIN OVER CENTRAL AND EASTERN
ALASKA.

FOR SOUTH CENTRAL ALASKA...PRECIPITATION CHANCES WILL GRADUALLY DROP
OFF THROUGH MONDAY AS THE GULF LOW MOVES OUT OF THE AREA. EVEN
THOUGH CYCLONIC FLOW REMAINS OVER THE AREA...PRECIPITATION CHANCES
WILL REMAIN VERY LOW AS THE SOURCE AIR IS DRY.

FOR SOUTHWEST ALASKA...THE UPPER LEVEL RIDGE WILL REMAIN OVER THE
AREA THROUGH WEDNESDAY. CONSIDERABLE CLOUDINESS OVER THE AREA WILL
SLOWLY DISSIPATE AS THE RIDGE AND ASSOCIATED INVERSION WEAKENS.

FOR THE BERING SEA AND ALEUTIANS...THE LOW OVER THE CENTRAL BERING
SEA WILL MOVE NORTH THROUGH MONDAY AFTERNOON AND THEN MOVE INLAND
OVER EXTREME EASTERN RUSSIA DURING THE EVENING. THE ASSOCIATED FRONT
WILL WORK EASTWARD NEARLY TO THE ALASKAN WEST COAST MONDAY AND THEN
DISSIPATE EARLY TUESDAY AS THE SUPPORTING LOW MOVES AWAY AND THE
WEST COAST RIDGE ASSERTS ITS DOMINANCE. A STRONG LOW WILL DEVELOP
SOUTHWEST OF THE WESTERN ALEUTIANS TONIGHT AND THEN MOVE EAST JUST
SOUTH OF THE ALEUTIAN ISLANDS UNTIL IT IS SITUATED SOUTH OF THE
CENTRAL ALEUTIANS ON WEDNESDAY. THE WEATHER FROM THIS LOW WILL MOVE
NORTH PAST THE PRIBILOFS AND EAST TO THE ALASKA PENINSULA BY
WEDNESDAY...BUT AGAIN STALL JUST WEST OF MAINLAND ALASKA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...STORM WARNING 175.
         GALE WARNING 172 176 179 185.
FIRE WEATHER...NONE.

LUDWIG MAR 13