Small Craft Advisory 117, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 AM AKST THU FEB 10 2011

.MODEL DISCUSSION...00Z MODELS IN REASONABLE ENOUGH AGREEMENT
ON KEY FEATURES TO ALLOW USE OF NAM FOR LOCAL EFFECTS...WITH
GFS FOR LARGER SCALE WINDS. ALL SHOW SIMILAR TIMING AND PRECIP.
PATTERN WITH OCCLUDED FRONTAL SYSTEM MOVING ONSHORE GULF COAST
FROM PRINCE WILLIAM SOUND EAST TONIGHT THROUGH FRIDAY MORNING.

.ANALYSIS AND UPPER LEVELS...PATTERN CHANGE UNDERWAY. FAST WRLY
JET OVER WRN AND CENTRAL N PACIFIC WILL BREAK DOWN UPPER RIDGE
OVER CENTRAL BERING LATE TONIGHT THROUGH FRI. THIS WILL PUSH AN
AMORPHOUS FRONTAL SYSTEM E ACROSS ALEUTIANS AND AK PEN. TONIGHT
THROUGH FRI NIGHT. UPPER LOW OVER N PACIFIC S OF PADQ CENTERED
AT 45-50N HAS OCCLUSION ARCING UP INTO GULF AK. SURFACE LOW AND
FRONT WILL WOBBLE N LATE TODAY AND FRI. STRONGEST PORTION OF
FRONT WITH HEAVIEST PRECIP. WILL MOVE ONSHORE CENTRAL AND ERN
GULF COAST TONIGHT THROUGH FRI MORNING. PADQ AND WRN HALF KENAI
WILL ONLY SEE GLANCING PRECIP. FROM THIS...THOUGH WINDS WILL
INCREASE TO GALE FORCE. MAJOR PATTERN CHANGE OCCURS FRI NIGHT
AND SAT WHEN FAST NWRLY JET BREAKS THROUGH INTO WRN GULF. THIS
CAUSES UPPER TROUGH OVER INTERIOR AK TO SAG S...DRAGGING COLD
AIR S ACROSS AK RANGE. COLD UPPER TROUGH WILL REMAIN CENTERED
OVER ERN MAINLAND AK AND YUKON AT LEAST THROUGH MON. STRONG NRLY
PRESSURE GRADIENTS WILL BRING GUSTY N-E OUTFLOW WINDS USUAL AREAS
THROUGH GAPS/PASSES SAT-MON. AREAS NOT WINDY WILL SEE MUCH COLDER
TEMPERATURES...WELL BELOW AVERAGE...THROUGH MONDAY.

.SHORT TERM FORECAST...
SW AK/ALEUTIANS: TEMPS. DROPPING GREATLY TONIGHT AND STAYING COLD
THROUGH MONDAY SW AK AS NRLY FLOW ON BACK SIDE OF UPPER TROUGH
OVER MAINLAND AK DRIVES ARCTIC AIR S. STRONG WINDS AK PEN. FOR
THIS REASON THROUGH TONIGHT. STRONG NWRLY FLOW/FRONT SMASHING
THROUGH ALEUTIANS LATE TODAY THROUGH FRI WILL ALSO BRING STRONG
WINDS AND MIXED PRECIP. OR SNOW ALL THROUGH FRI AND SAT.

S-CENTRAL/GULF COAST/COPPER R. BASIN: RAIN OR MIXED PRECIP.
DEVELOPING TODAY GULF COAST FROM ERN HALF KENAI ON EAST AS
FRONT IN GULF MOVES ASHORE SPLITS AND WEAKENS. PRECIP. CHANGING
TO SNOW GULF COAST FRI AS COLD AIR ON BACK SIDE OF SURFACE LOW
ARRIVES. GUSTY WINDS WITH BLOWING SNOW FOR THOMPSON PASS TONIGHT
AND FRI...BUT NOT EXPECTING BLIZZARD THERE. OVER-RUNNING SNOW LIKELY
COPPER RIVER BASIN TONIGHT THROUGH FRI NIGHT WILL BRING SEVERAL
INCHES THERE...BUT NOT ENOUGH FOR ADVISORY. GALE TO STORM FORCE
OUTFLOW WINDS DEVELOPING LATE TONIGHT THROUGH FRI USUAL GAPS AND
PASSES...CONTINUING THROUGH THE WEEKEND AS SURFACE LOW MOVES N INTO
NRN GULF...THEN REMAINS.

.LONG TERM FORECAST...LONG-WAVE UPPER TROUGH TO REMAIN CENTERED
OVER AK EXTENDING WELL S INTO PACIFIC THROUGH AT LEAST MON NIGHT.
CLEAR AND COLD FROM AK PEN. E WITH SURFACE HIGH PRESSURE OVER
MAINLAND CONTINUING TO DRIVE COLD AIR THROUGH GAPS/PASSES. LESS
WINDY AREAS WILL HAVE WELL-BELOW AVERAGE TEMPS. WEAKENING UPPER
TROUGH AND SURFACE FRONTAL SYSTEM WILL TRAVERSE ALEUATIANS AND AK
PEN SUN NIGHT THROUGH TUE...BRINGING RAIN/SNOW AND MORE STRONG WINDS.
THIS COULD BRING SNOW TO SW AK LATE NEXT TUE/TUE NIGHT AS WELL.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE: 120 121 127 132 138 351 352 411 412 413 155 160
               165 170 172 175 176 185
        STORM: 130 150
FIRE WEATHER...NONE

MAR FEB 11