Small Craft Advisory 857, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM ADT MON OCT 24 2005

.DISCUSSION...

UPPER LEVELS...LARGE CLOSED LOW OVER THE GULF OF ALASKA WITH A RIDGE
OVER THE WESTERN U.S. AND THE BERING SEA TODAY. SHORT WAVE TROUGH
MOVING INTO THE WESTERN ALEUTIAN WITH SOME JET SUPPORT ON THE
SOUTHERN EDGE OVER THE ALEUTIAN CHAIN. THIS WILL SHOOT THROUGH THE
RIDGE AND TEMPORARILY FLATTEN IT TONIGHT. HOWEVER...RIDGE TO BOUNCE
BACK TOMORROW AS A LONGER WAVE TROUGH MOVES NEAR THE KAMCHATKA
PENINSULA. LOW TO REMAIN OVER THE GULF AS THE RIDGE GETS SQUEEZED BY
PROGRESSIVE LONG WAVE TROUGH. HIGH CENTER PUSHED TO CHUKOTSK
PENINSULA THURSDAY AS LOW CUTS UNDERNEATH. BY THIS TIME...PIECE OF
GULF LOW DEVELOPS INTO STRONG LOW OVER THE YUKON AND HAS HELPED PUSH
WESTERN U.S. RIDGE A BIT FARTHER EAST. THE BERING LOW FEEDS INTO GULF
LOW AND RIDGE MOVES OVER THE WESTERN BERING THIS WEEKEND.

SURFACE...LOW NORTHWEST OF SHEMYA WITH A FRONT EXTENDING INTO THE
CENTRAL ALEUTIAN CHAIN. JET ALIGNED ALONG THE SOUTHERN EDGE OF THE
FRONT. APPARENT IN THE IR IMAGERY THAT FRONT IS SPLITTING AS ALL THE
ENERGY WITH THE SOUTHERN FLANK. THE LOW TO WEAKEN AS A RESULT WITH
THE FRONT CONTINUING IN THE BASE OF THE GULF LOW BY TOMORROW. THE
GULF LOW IS A LARGE COMPLEX WITH A STRONG JET RUNNING UP THE
PANHANDLE. THIS IS FEEDING A SECONDARY LOW WHICH WILL BECOME THE
DOMINANT LOW UNDERNEATH THE UPPER LEVEL GULF LOW. THIS LOW ALONG THE
PANHANDLE TO DRIVE NORTH AND WEST TONIGHT AND WEAKEN AS IT FADES AWAY
TO THE WEST SOUTH OF THE PRINCE WILLIAM SOUND. A WAVE ALONG THE JET
FARTHER SOUTH TO WORK INTO THE PANHANDLE TOMORROW. THIS IS WHERE THE
MODELS START TO DIFFER ON THE SURFACE. WILL HAVE TO LEAN TOWARD THE
ETA IN THE SHORT TERM THAN RUN WITH THE GFS AFTER 48 HOURS. THE GFS
WANTS TO BRING ANOTHER LOW NORTH AND WEST WHILE THE NAM AND UKMET
PUSH IT INLAND WEDNESDAY NIGHT. IN THE MEANTIME...A LOW MOVES TO THE
KAMCHATKA PENINSULA WITH STRONG JET SUPPORT. THIS LOW TO HOLD
TOGETHER AND SQUEEZE THE RIDGE OVER THE ALEUTIAN CHAIN WEDNESDAY AND
THURSDAY. A STRONG PRECEDING FRONT TO WORK ACROSS THE ALEUTIANS WITH
THE JET. THIS FRONTAL AND JET FEATURE TO EVENTUALLY FEED INTO THE
GULF LOW BY FRIDAY. THE UPPER LEVEL LOW WITH ITS SURFACE COUNTERPART
OVER THE BERING SEA TO WORK INTO THE GULF AS WELL THROUGH THE
WEEKEND. THIS WILL ALLOW A RIDGE TO DEVELOP OVER THE BERING SEA WITH
ANOTHER LOW TO PUSH INTO THE WESTERN ALEUTIANS LATE SUNDAY.

DETAILS...FRONT MOVING THROUGH THE BERING SEA PRODUCING GALE FORCE
WINDS AND PLENTY OF RAINFALL. OVER THE EASTERN ALEUTIANS AND
SOUTHWEST ALASKA...THERE IS A GOOD GRADIENT FROM THE HIGH OVER THE
CENTRAL ALEUTIANS AND LOW OVER THE GULF. THIS IS MAKING FOR STRONG
NORTH WINDS OVER THESE AREAS. THIS GRADIENT TO RELAX LATE THIS
AFTERNOON AND TONIGHT AS THE HIGH MOVES OVER THE AREA. THE GALE FORCE
WINDS WITH THE FRONT WILL ALSO WEAKEN AS THE FRONT SPLITS AND HEADS
SOUTH OF THE CHAIN. THE LOW OVER THE GULF HAS MANY CIRCULATIONS
ASSOCIATED WITH IT. SMALL CRAFT ADVISORIES DUE TO WAVES MOSTLY
TODAY...BUT WINDS WILL PICK UP FROM THE WEST AS THE GRADIENT OVER
BRISTOL BAY MOVES OVER THE WESTERN GULF TONIGHT. WINDS WILL RELAX
TOMORROW AS THE GRADIENT LOOSENS. LOW WORKING UP THE PANHANDLE TO
WEAKEN AS IT MOVES AWAY FROM ITS JET SUPPORT TO NEAR PRINCE WILLIAM
SOUND TONIGHT. HOWEVER...MOISTURE TO ACCOMPANY THIS LOW WITH SNOW
SHOWERS EXTENDING ALONG THE COAST AND EASTERN PORTIONS OF THE COPPER
RIVER BASIN. DO NOT EXPECT ANY SHOWERS TO PUSH INTO THE ANCHORAGE
AREA THOUGH. THE LOW WEAKENS UNDER THE UPPER LEVEL LOW WITH LITTLE
JET SUPPORT. THIS IS LIMITED TO THE EDGES OF THE LOW TO THE SOUTH AND
ALONG THE PANHANDLE. DUE TO THE INSTABILITY OF THE AIR MASS OVER THE
GULF...ISOLATED THUNDERSTORMS WILL BE POSSIBLE THROUGH THE NEXT
COUPLE DAYS. IN ADDITION...WITH THE FLOW MORE NORTHEASTERLY OVER THE
LAND...NORTH-SOUTH ORIENTED GAPS WILL EXPERIENCE ENHANCED FLOW
THROUGH TONIGHT.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...STORM 176
         GALE 155 160 165 170 172 175 180
FIRE WEATHER...NONE

JN OCT 05