Small Craft Advisory 384, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM ADT THU MAY 1 2008

.ANALYSIS AND UPPER LEVELS...
THE MAIN FEATURE TODAY IS THE LOW MOVING INTO THE GULF OF ALASKA AND
THE ASSOCIATED FRONT PUSHING TO THE NORTH GULF COAST SUPPORTED BY AN
UPPER LOW OVER THE GULF. ANOTHER UPPER LOW IS OVER THE KUSKOKWIM
DELTA WITH A WEAK SURFACE REFLECTION THAT IS PRODUCING LIGHT SNOW
OVER THE REGION. A BLOCKING RIDGE OF HIGH PRESSURE IS IN PLACE OVER
THE CENTRAL AND EASTERN BERING SEA. COLD NORTHERLY FLOW CONTINUES
ACROSS WESTERN ALASKA AND THE ALASKA PENINSULA. LITTLE CHANGE IS
EXPECTED IN THE OVERALL PATTERN IN THE SHORT TERM THROUGH SUNDAY.

.MODEL DISCUSSION...
IN THE SHORT TERM THE MODELS ARE IN FAIRLY GOOD AGREEMENT. THE FIRST
INDICATION OF DIVERGENCE IN MODEL SOLUTION IS SAT AFTERNOON WHEN THE
ECMWF HOLDS THE NEXT LOW FURTHER SOUTH AND WEST THAN THE UKMET GFS
AND NAM. THIS DIVERGENT SOLUTION PROPAGATES THROUGH SUN.

.SHORT TERM FORECAST...
SOUTHCENTRAL...
THE ANTICIPATED PRECIPITATION ACROSS THE SOUTH CENTRAL REGION HAS NOT
MATERIALIZED AS EXPECTED. AS THE GULF LOW DRIFTS NORTH AND WEST AND
SLOWLY WEAKENS TONIGHT WE EXPECT THE PRECIPITATION TO SPREAD INTO THE
SOUND AND SOUTHERN COOK INLET TONIGHT. THE FRONT WILL PUSH ACROSS THE
CHUGACH MOUNTAINS INTO THE EASTERN INTERIOR BY FRI AFTERNOON. A WEAK
LOW WILL FORM IN THE EASTERN COPPER RIVER BASIN TO EASTERN TANANA
VALLEY THAT IS EXPECTED TO INCREASE THE THREAT OF PRECIPITATION AVER
THE REGION. MOST OF THIS SHOULD BE IN THE TANANA VALLEY AND EASTERN
COPPER RIVER BASIN.

THE UPPER LOW DROPPING SOUTH FROM THE KUSKOKWIM DELTA WILL MERGE INTO
THE GULF LOW AND MOVE ACROSS KODIAK ISLAND FRI. THE BLOCKING RIDGE
WEAKENS AND DRIFTS WEST THROUGH SUN. THE WEAK LOW FORMING NEAR 40N
178W MOVES NORTHEAST INTO THE GULF LOW COMPLEX BY SAT EVENING. SINCE
THESE LOWS ARE REMAINING SOUTH OF THE MAINLAND THE COLDER AIR NOW
OVER THE WESTERN INTERIOR WILL PERSIST AND EVEN WRAP AROUND THE UPPER
LOW INTO THE SOUTH CENTRAL REGION THIS WEEKEND. THIS SECOND LOW MOVES
IN TO REPLACE THE CURRENT GULF LOW AND WILL KEEP THE COOL NORTHERLY
FLOW OVER THE MAINLAND TO THE EASTERN BERING SEA.

BERING SEA/ALEUTIANS...
THE RIDGE OF HIGH PRESSURE WILL FADE TO THE NORTH AND WEST THROUGH
THE WEEKEND. THE PERSISTING NORTHERLY FLOW WILL HOLD THE LOW CLOUDS
IN ALONG THE ALASKA PENINSULA. EXPECT THE GUSTY GAP WIND TO CONTINUE
ACROSS THE PENINSULA UNTIL FRI EVENING AT WHICH POINT THE CONTINUED
WEAKENING OF THE GOLF LOW AND THE INCOMING LOW FROM THE SOUTHWEST
WILL RELAX THE GRADIENT.

.LONG TERM FORECAST...
LOW PRESSURE WILL PERSIST OVER THE GULF AND THE INCOMING LOW FROM THE
SOUTHWEST WILL INTENSIFY IN THE GULF SAT NIGHT. AN INTENSIFYING LOW
IS EXPECTED TO TRACK FROM EAST TO WEST ALONG THE ALEUTIAN CHAIN
SUNDAY THROUGH WEDNESDAY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE WARNING ZONES 120 130 132 351 352.
FIRE WEATHER...NONE.

SAM MAY 08