Small Craft Advisory 120, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 AM AKST FRI FEB 11 2011

.MODEL DISCUSSION...MODELS IN GOOD AGREEMENT THROUGH SHORT
TERM WITH DETAILS OF SURFACE LOW IN NRN GULF AK AND OCCLUDED
FRONTAL SYSTEM MOVING INLAND FROM GULF COAST THIS MORNING
THROUGH TODAY/TONIGHT. AND ALSO WITH FAST-MOVING SHORT-WAVE
AND FRONTAL SYSTEM MOVING ACROSS ERN ALEUTIANS AND AK PEN.
LATE TODAY THROUGH EARLY SAT. SO USED NAM MAINLY TO MAKE
ADJUSTMENTS TO CURRENT FORECASTS.

.ANALYSIS AND UPPER LEVELS...WEAKENING UPPER/SURFACE LOW
OVER KAMCHATKA HAS OCCLUDED FRONTAL SYSTEM ARCING OUT OVER
NRN/CENTRAL BERING. THIS SYSTEM WILL SLIDE E ACROSS ALEUTIANS
AND AK PEN TODAY/TONIGHT...WEAKENING FURTHER AS IT MOVES
THROUGH AND BREAKS DOWN UPPER RIDGE. VERTICALLY STACKED LOW
IN THE NRN GULF AK WILL WEAKEN TODAY/TONIGHT BUT RESIDUAL
SURFACE LOW WILL REMAIN IN PLACE THROUGH SUN. OCCLUDED FRONT
WITH THIS CURRENTLY MOVING INLAND OVER GULF COAST AND COPPER
R. BASIN WILL CONTINUE MIXED PRECIP. ALONG THE COAST AND SNOW
INLAND INTO TONIGHT. BERING SHORT-WAVE DIVING INTO BASE OF
UPPER TROUGH THAT CURRENTLY COVERS ALL MAINLAND AK WILL DEEPEN
IT FURTHER SAT...HELPING MORE COLD AIR DIVE S FROM INTERIOR OVER
AK PEN. E ALL THROUGH SW AND S-CENTRAL AK THROUGH SUN NIGHT.
GUSTY NRLY OUTFLOW GAP WINDS DEVELOPING TODAY AND CONTINUING
THROUGH SUN USUAL AREAS.

.SHORT TERM FORECAST...

SW AK/ALEUTIANS: GALE FORCE WINDS TODAY/TONIGHT ALEUTIANS WITH
AND BEHIND FRONT FROM KAMCHATKA LOW. STRONG WIND CRITERIA WILL
BE MET MOST ZONES TODAY/TONIGHT. MIXED PRECIP. WILL CHANGE TO
SNOW SHOWERS BEHIND FRONT. STRONG NWRLY FLOW BEHIND FRONT WILL
CONTINUE SNOW SHOWERS ERN ALEUTIANS AND AK PEN. SAT. RIDGING
WILL BUILD OVER WRN ALEUTIANS SAT/SUN AHEAD OF NEXT LOW. THIS
WILL BRING MORE GALE FORCE WINDS AND RAIN TO WRN ALEUTIANS MON.
ONLY ISOLATED -SHSN TODAY OUTER BERING SEA COAST FROM WEAKENING
FRONT. OTHERWISE COLD AND BREEZY FOR SW AK TODAY THROUGH SUN
UNDER BRISK N TO NW LOW TO MID LEVEL FLOW.

S-CENTRAL/GULF COAST/COPPER R. BASIN: OVER-RUNNING SNOW FROM
REMAINS OF OCCLUSION AROUND NRN GULF LOW WILL CONTINUE TODAY
FROM PANC N TO PAAQ...E OVER COPPER R. BASIN. UP TO 2 INCHES
TODAY PANC BOWL...WITH 4 TO 8 COPPER BASIN. 2 TO 3 INCHES BY
TONIGHT PAVD AND PAWR. GUSTY W WINDS WITH COLD ADVECTION AND
SNOW WHITTIER NECESSITATES BLIZZARD WARNING THERE TODAY. SNOW
DIMINISHING FROM W TONIGHT...ENDING COPPER BASIN BY LATE MORNING
TOMORROW. GUSTY NRLY WINDS WITH COLD ADVECTION NEAR AK RANGE
THROUGH SUN SO HAVE WIND CHILL ADVISORY FOR 145 UNTIL NOON SUN.
NOT EXPECTING HIGH WIND CRITERIA FOR OUTFLOW WINDS USUAL GAPS
BUT STRONG WIND HEADLINES FOR ALL THOSE TODAY THROUGH SAT AND
SUN.

.LONG TERM FORECAST...UPPER RIDGING FROM WRN ALEUTIANS WILL MOVE
E OVER REST OF CHAIN AND AK PEN. SUN AND MON BRINGING WARMING.
ECMWF AND GFS AGREE ON PROGRESSIVE PATTERN SO SHORT-WAVE FROM WRN
ALEUTIANS WILL SLIDE E ACROSS AK PEN. AND SW AK TUE NIGHT. SNOW
WILL MAKE IT AT LEAST AS FAR E AS PADQ BY THEN. 00Z RUNS OF EC AND
GFS WERE AT ODDS AT DAY 6...EC SHOWING SIGNIFICANT SURFACE LOW
MOVING INTO GULF AK WITH UPPER SHORT-WAVE...WHICH WOULD BRING SNOW
EVENT TO S-CENTRAL AND GULF COAST. WHILE GFS HAD MUCH WEAKER SYSTEM
WITH NO SIGNIFICANT PRECIP. MAINTAINED CONTINUITY FOR NOW IN EXTENDED
USING GFS. COLD BELOW AVERAGE TEMPS. WILL CONTINUE S-CENTRAL...GULF
COAST AND COPPER R. BASIN THROUGH MON/TUE WITH LITTLE MODERATION
UNTIL AT LEAST WED. GUSTY OUTFLOW WINDS WILL BEGIN TO DIMINISH TUE
AS SURFACE HIGH OVER INTERIOR SHIFTS E AHEAD OF PROGRESSIVE UPPER
RIDGE.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 125 WHITTIER
         WINTER CHILL ADVISORY 145
         WINTER WEATHER ADVISORY 141

MARINE...GALE: 121 127 129 132 138 155 165 170 171 172 175 176
               185 351 352 411 413 414
        STORM: 130 150
HEAVY FREEZING SPRAY: 185 165 160 150 141 140 138 130 129 128
                      127 126 121 414
FIRE WEATHER...NONE

MAR FEB 11