Small Craft Advisory 449, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM ADT THU MAY 22 2008

.ANALYSIS AND UPPER LEVELS...
THE MAIN FEATURE REMAINS THE NORTH PACIFIC STORM SUPPORTED BY THE
DEEP STRONG UPPER LOW AND TROUGH FROM THE BERING SEA SOUTH INTO THE
NORTH PACIFIC. THE JET HAS DIMINISHED TO AROUND 150 KT FROM 200 KT
YESTERDAY. THE LATEST SATELLITE LOOP INDICATES THE INCOMING NORTH
PACIFIC STORM IS RAPIDLY INTENSIFYING. THE WEAK LOW THAT WAS OVER THE
EASTERN ALEUTIANS HAS DISSIPATED. HIGH PRESSURE REMAINS OVER THE GULF
OF ALASKA TO THE BRISTOL BAY AREA. THE THERMAL TROUGH HAS MOVED NORTH
AND EXTENDS ALONG THE YUKON RIVER VALLEY WHICH IS EXPECTED TO MOVE
THE FOCUS OF THUNDERSTORM ACTIVITY TO THE NORTHERN EDGE OF THE
ANCHORAGE AOR THIS EVENING.

.MODEL DISCUSSION...
RUN TO RUN CONSISTENCY HAS IMPROVED FR THE GFS AND THE MODELS ARE IN
VRY GOOD AGREEMENT THROUGH FRI AFTERNOON. THE GFS ECMWF AND UKMET
STAY IN CLOSE AGREEMENT AFTER FRI AFTERNOON AND THE NAM IS THE
OUTLIER HOLDING THE SURFACE LOW SOUTH OF THE OTHER SOLUTIONS.
THE GFS HAS BEEN TRENDING TO A SLOWER AND MORE WEST SOLUTION HOWEVER
THE LATEST NAM HAS BEEN SLOWER THAN PREVIOUS RUNS AND AT THIS POINT
WE ARE LEANING TOWARD THE CONSENSUS SOLUTION OF THE GFS UKMET AND
ECMWF. AFTER SATURDAY THE MODELS IN GOOD AGREEMENT WITH THE
ESTABLISHING OF A LARGE HIGH FROM THE NORTH PACIFIC INTO SOUTH
CENTRAL ALASKA THAT SHOULD HOLD OVER THE AREA WELL INTO THE MIDDLE OF
NEXT WEEK.

.SHORT TERM FORECAST...
EXPECT THE MOIST SOUTHEAST AND SOUTH FLOW TO MOVE OVER THE SOUTH
CENTRAL REGION BY FRI MORNING. COASTAL AREAS WILL SEE A GOOD SHOT OF
RAIN WITH THIS SYSTEM FRI FOLOWED BY PERSISTING SOUTHERLY UPPER LEVEL
FLOW THAT WILL KEEP THE THREAT OF RAIN OVER SOUTH CENTRAL ALASKA INTO
SAT. EXPECT EXTENSIVE MARINE STRATUS AND FOG OVER THE GULF TO PRINCE
WILLIAM SOUND BY SAT AS THE HIGH BUILDS IN BEHIND THE STORM.

A STRONG WEATHER FRONT ASSOCIATED WITH LOW PRESSURE AROUND THE
ALASKA PENINSULA MOVES INTO THE WESTERN GULF TONIGHT AND NORTHERN
GULF FRIDAY. THIS FRONT IS EXPECTED TO BRING MODERATE TO HEAVY RAIN
TO THE UPSLOPE AREAS OF PRINCE WILLIAM SOUND AND THE KENAI PENINSULA
SOUTHWEST TO KODIAK ISLAND AND THE EAST SIDE OF THE ALEUTIAN RANGE.
WE HAVE UPPED THE WIND FORECASTS TO STORM FORCE ALONG THE ALASKA
PENINSULA TONIGHT AS THE NORTH PACIFIC STORM APPROACHES. THE FRONT
WILL DISSIPATE AS IT MOVES INLAND LATE FRIDAY AND FRIDAY NIGHT WITH.

STRONG GAP WIND ACROSS THE KENAI PENINSULA WILL PRODUCE THE TYPICAL
ANCHORAGE HILLSIDE AND TURNAGAIN ARM WIND. AFTER THE FRONT MOVES
INLAND AND THE INTERIOR TROUGH SETS UP THE COMBINATION OF THE
INTERIOR TROUGH AND BUILDING HIGH IN THE GULF WILL PRODUCE THE GUSTY
SOUTH WIND ALONG THE COPPER RIVER LATE FRIDAY.

SOUTHWEST MAINLAND...
GUSTY EAST WIND WILL DEVELOP TONIGHT AS THE STRONG STORM MOVES INTO
THE ALASKA PENINSULA REGION. EXPECT THE PRECIPITATION TO START ALONG
THE ALASKA PENINSULA AND SPREAD NORTH AND EAST TO THE UP SLOPE
REGIONS OF THE BRISTOL BAY REGION. THE DOWNSLOPING ALONG THE LEE SIDE
OF THE ALEUTIAN MOUNTAINS WILL REDUCE THE AMOUNT OF PRECIPITATION
OVER SOUTHWEST ALASKA. THE PERSISTING SOUTHERLY FLOW ALOFT WILL HOLD
THE COOL MOIST CLOUDY CONDITIONS OVER THE BERING SEA COASTAL AREAS
THROUGH THE WEEKEND.

BERING SEA/ALEUTIANS...
THE RAPIDLY INTENSIFYING LOW MOVING TO THE ALASKA PENINSULA IS
EXPECTED TO MOVE THROUGH THE FALSE PASS AREA FRI MORNING THEN WEAKEN
AS IT SLOWS DOWN MOVING NORTH INTO THE BERING SEA. THIS STORM IS
PUSHING COOL LOW LEVEL AIR ACROSS SOUTHWEST ALASKA AND PRECIPITATION
ACROSS MUCH OF THE REGION WILL BE MIXED WITH SNOW AT TIMES ESPECIALLY
IN THE PRIBILOFS.

.LONG TERM FORECAST...
MODELS ARE IN PRETTY GOOD AGREEMENT FOR NEXT WEEK WITH THE LARGE
PACIFIC HIGH IN THE GULF TO SOUTH CENTRAL ALASKA THAT IS EXPECTED TO
PERSIST INTO THE MIDDLE OF NEXT WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...STORM 155 150. GALE 130 132 138 160 165 170 180 351 352
         414.
FIRE WEATHER...NONE.

SAM MAY 08