Small Craft Advisory 298, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM ADT WED APR 2 2008

.MODEL DISCUSSION...MODEL INITIALIZATIONS REASONABLE. FORECAST TREND
OVER THE BERING SEA SEEMS TO BE HANDLED BEST BY THE GFS MODEL. THE
POSITIONING OF PRESSURE CENTERS OVER THE NORTHERN GULF OF ALASKA
DIFFERS CONSIDERABLY ON THIS MODEL RUN. THE MAIN CHANGE HAS BEEN TO
DEVELOP THE LOW PRESSURE CENTER OVER THE SOUTHERN GULF OF ALASKA AND
WEAKEN THE CENTER NEAR KODIAK FRI AFTERNOON AND SAT. THE GFS ENSEMBLE
TENDS TO SHOW THE OPPOSITE WITH A LOW CLUSTER NEAR KODIAK WITH OPEN
TROUGH TO SE. SO IN GENERAL WILL BLEND TOWARD THE 12Z GFS MODEL WITH
CAUTION ON THIS FORECAST PACKAGE.

.UPPER LEVELS...
SHORT WAVE OVER THE BERING SEA WEAKENS AS IT MOVES OVER THE EASTERN
MAINLAND/GULF OF ALASKA THU. LONG WAVE DIGS OVER THE EASTERN BERING
SEA/CENTRAL ALEUTIANS THU AFTERNOON WITH A FAIRLY WELL DEVELOPED
CENTER OVER THE GULF OF ANADYR. THIS CENTER INTENSIFIES AS IT MOVES
TO OVER THE BERING STRAIT FRI NIGHT THEN BECOMES NEARLY STATIONARY
AND WEAKENS THROUGH SUN. ASSOCIATED TROUGH MOVES DIGS SE TO THE GULF
OF ALASKA FRI AND SAT. A SECONDARY CENTER FORMS NEAR KODIAK ISLAND
SAT EVENING THEN MOVES TO THE SE GULF AND WEAKENS SUN. W TO NW JET
SETS UP OVER THE BERING SEA ON THE BACKSIDE OF TROUGH THU NIGHT. THE
JET SHIFTS TO THE EASTERN BERING SEA/AK PEN FRI NIGHT/SAT AS A RIDGE
BUILDS OVER THE WESTERN BERING SEAS AND ALEUTIANS.

.SHORT TERM FORECAST...
.EAST...WEAK TROUGH MOVES THROUGH THE EASTERN MAINLAND TONIGHT.
FRONTAL TROUGH OVER THE BERING SEA BRINGS ANOTHER ROUND OF MOISTURE
TO SOUTHCENTRAL THU. SHOULD SEE MEASURABLE SNOW AMOUNTS OVER THE
SUSITNA VALLEY (MAINLAND NORTH/HIGHER ELEVATIONS) WITH SW FLOW IN THE
LOW TO MID LEVELS. TEMPS AT LOWER ELEVATIONS LIKELY TO BE WARM ENOUGH
FOR MIXED PRECIPITATION...SO NOT LOOKING FOR MUCH ACCUMULATION. UPPER
TROUGH DIGGING TO WEST WOULD KEEP THE THREAT OF PRECIPITATION IN MOST
ZONES. TEMPS ALOFT COOL OVER THE WEEKEND AS THE UPPER TROUGH PUSHES
EAST. THIS LIKELY WILL TRANSLATE INTO COOLER SURFACE TEMPS AND SNOW
AS THE PRIMARY PRECIPITATION TYPE.

.WEST...LOWER 980S SURFACE LOW OVER THE WESTERN GULF MOVES TO NEAR
SAINT LAWRENCE THU THEN WEAKENS AS IT MOVES TO THE WESTERN ARCTIC
COAST FRI NIGHT. ASSOCIATED WARM OCCLUSION RAPIDLY APPROACHING SAINT
PAUL ISLAND THIS AFTERNOON MOVES TO THE EASTERN BERING SEA THIS
EVENING AND INLAND OVER NIGHT. OBSERVATIONS SHOW FAIRLY WARM AIR ON
THE BACKSIDE OF THIS SYSTEM...SO SNOW SHOULD CHANGE TO RAIN OR MIXED
OVER THE PRIBILOFS LATER THIS AFTERNOON. SNOW AND BLOWING SNOW IN
ADVANCE OF THIS CENTER LIKELY TO BRING BLIZZARD CONDITIONS TO ZONES
155 COAST AND CAPES 161 TONIGHT. TEMPS SHOULD WARM ENOUGH THU...SO
PRECIPITATION SHOULD BECOME MIXED. A COLD FRONT WITH A SECONDARY LOW
FORMS OVER THE BERING SEA WITH COLD ADVECTION AND MOVES TO THE JUST
EAST PRIBILOFS AND EASTERN ALEUTIANS THU NIGHT NIGHT. THE LOW CENTER
DROPS TO NEAR KODIAK/EASTERN BRISTOL BAY FRI AND COLD FRONT STALLS
OVER SW ALASKA. COLDER AIR EVENTUALLY CREEPS FURTHER EAST OVER THE
WEEKEND.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNINGS UPCOMING ZONES 155 AND 161.
MARINE...GALES 179 AND 180.
FIRE WEATHER...NONE.

RMC APR 08