Small Craft Advisory 54, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM AST SAT JAN 13 2007

.DISCUSSION...
MODELS HAVE INITIALIZED LOW SOUTH OF THE CENTRAL ALEUTIAN CHAIN WELL
THIS MORNING...ESPECIALLY THE GFS AND UKMET. IN CONTRAST...THE
EASTERN PORTION OF THE LOW WHICH HAS DEVELOPED A TRIPLE POINT LOW HAS
NOT BEEN HANDLED ALL THAT WELL. THE ACTUAL LOW IS A BIT FARTHER EAST
AND FASTER THAN THE MODELS HAVE PREDICTED. THE OVERALL PREDICTION OF
WHERE THE LOW WILL END UP IS BELIEVED TO BETTER HANDLED BY THE GFS
AND UKMET AT THIS TIME. AN EMERGING LOW OUT OF THE NORTHWEST PACIFIC
IS BELIEVED IT WILL FOLLOW A TRACK SIMILAR TO WHAT THE ECMWF AND GFS
HAVE FORECASTED FOR EARLY THIS WEEK THROUGH MID WEEK. THE UNCERTAINTY
WITH THIS LOW IS SLIGHT...BUT THE GFS ENSEMBLES HINT THAT THE LOW MAY
BE FARTHER WEST THAN THE OPERATIONAL RUN WANTS TO TREND THE LOW
WEDNESDAY AND THURSDAY.

UPPER LEVELS...A BROAD TROUGH OVER THE WESTERN BERING SEA WITH A
CLOSED LOW SOUTH OF THE CENTRAL ALEUTIAN CHAIN. A RIDGE OF HIGH
PRESSURE IS OVER THE NORTHERN GULF BACK TO SOUTHWEST ALASKA. A QUICK
MOVING SHORT WAVE MOVED THROUGH SOUTH CENTRAL THIS MORNING AND IS
EXITING QUICKLY THIS AFTERNOON. THIS WAS ASSOCIATED WITH THE CLOSED
LOW OVER WESTERN ALASKA NEAR THE YUKON DELTA. A SHORT WAVE MOVING OUT
OF THE LOW IN THE CENTRAL ALEUTIANS TO ROTATE UP TO THE NORTHERN GULF
COAST TONIGHT WITH A SURFACE REFLECTION. THE MAIN CLOSED LOW IN THE
CENTRAL ALEUTIANS TO MOVE INTO THE GULF SUNDAY AFTERNOON/EVENING. A
PIECE OF THE LOW IN WESTERN ALASKA DROPS INTO SOUTH CENTRAL ALASKA
MONDAY AS A RIDGE BUILDS OVER THE EASTERN BERING AND SOUTHWEST
ALASKA. THIS IS IN RESPONSE TO A LARGE LOW MOVING INTO THE WESTERN
ALEUTIAN CHAIN. THIS SYSTEM PUSHES A RATHER STRONG SHORT WAVE ACROSS
THE EASTERN ALEUTIANS TUESDAY AND TO THE MAINLAND TUESDAY NIGHT. THIS
WAVE WILL ACT TO PUSH THE RIDGE OVER THE EASTERN BERING OVER THE GULF
AND SOUTH CENTRAL TUESDAY AND SUBSEQUENTLY RIDE THE TROUGH OVER THE
GULF TO THE PANHANDLE. AFTER THE WAVE MOVES THROUGH THE MAINLAND
TUESDAY...A STRONG RIDGE BUILDS OVER THE EASTERN GULF AND PANHANDLE
WEDNESDAY.  OVERALL THE PATTERN STAYS WITH A MEAN TROUGH OVER THE
WESTERN AND CENTRAL BERING AND A MEAN RIDGE OVER THE GULF THROUGH THE
END OF THE WEEK. HOWEVER...WE WILL SEE SYSTEM MOVE AROUND THE TROUGH
AND INTO THE MAINLAND AGAIN FRIDAY.

SURFACE EAST OF THE ALASKA RANGE...PRECIPITATION FROM THE QUICK LOW
MOVING THROUGH THE AREA THIS MORNING AND EARLY AFTERNOON SOON TO EXIT
THE AREA. NEXT BIG SYSTEM IS A TRIPLE POINT LOW THAT WILL DRIVE TO
THE NORTHERN GULF TONIGHT. THE BULK OF THE PRECIPITATION TONIGHT AND
TOMORROW WILL BE FROM PRINCE WILLIAM SOUND EAST. GOOD JET SUPPORT
WITH THE LOW INITIALLY AS WELL MAKING FOR SOME STRONG WINDS AND
MODERATE PRECIPITATION TO REACH THE COAST AND AROUND THE SOUND. AS
THE LOW SETTLES INTO THE NORTHERN GULF AND THE FLOW BECOMES MORE
EASTERLY OVER THE MAINLAND SUNDAY...PRECIPITATION WILL SPREAD TO THE
WEST SUNDAY NIGHT AND MONDAY. SOME MODERATE AMOUNTS OF SNOW MAY BE
EXPERIENCED OVER THE AREAS WEST OF THE SOUND. IN ADDITION...SOME COLD
AIR ADVECTION FROM THE WEST WILL PROVIDE A GOOD BOUNDARY FOR SNOWFALL
AND ALSO ENHANCE SOME WINDS THROUGH THE BARREN ISLANDS AND TURNAGAIN
ARM. THE LOW WILL BE PUSHED EAST OF THE AREA MONDAY NIGHT. THE WINDS
WILL CONTINUE INTO TUESDAY MORNING AS THE LOW MOVES OUT. A STRONG
FRONT WITH VERY GOOD JET SUPPORT TO MOVE TO KODIAK TUESDAY AND SOUTH
CENTRAL TUESDAY NIGHT. STRONG SURFACE WINDS AND GOOD AMOUNTS OF
PRECIPITATION WILL ACCOMPANY THIS FRONT. ANOTHER SOMEWHAT WEAKER
FRONT WILL FOLLOW WEDNESDAY AND WEDNESDAY NIGHT.

SURFACE WEST OF THE ALASKA RANGE...LOW CURRENTLY SOUTH OF THE CENTRAL
ALEUTIANS BRINGING MODERATE TO STRONG EASTERLY WINDS TO THE CENTRAL
AND EASTERN ALEUTIAN CHAIN. NOT MUCH PRECIPITATION WITH THIS SYSTEM.
UPPER LEVEL LOW MOVING THROUGH WESTERN ALASKA BRINGING SOME LIGHT
AMOUNTS OF PRECIPITATION TO THAT AREA. THIS LOW WILL EXIT THE REGION
TONIGHT. THE LOW OVER THE CENTRAL ALEUTIANS MOVES SOUTH OF THE GULF
SUNDAY. IN THE MEANTIME...A LARGE LOW PRESSURE SYSTEM WORKS TO THE
WESTERN ALEUTIAN CHAIN WITH GREAT UPPER LEVEL SUPPORT. STRONG JET
PUSHING THE FRONT ASSOCIATED WITH THIS LOW TO THE CENTRAL AND EASTERN
ALEUTIAN CHAIN MONDAY. THE LOW ITSELF CROSSES THE CHAIN NEAR ADAK
MONDAY NIGHT AND REMAINS JUST NORTH OF ADAK INTO WEDNESDAY. VERY
STRONG SURFACE WINDS WILL ACCOMPANY THE FRONT MONDAY NIGHT AS IT
MOVES THROUGH THE EASTERN ALEUTIANS AND TOWARD THE SOUTHWEST COAST.
THE FRONT PUSHES INLAND TUESDAY WITH GOOD AMOUNTS OF PRECIPITATION
THROUGH SOUTHWEST ALASKA AND AROUND THE LARGE LOW. ANOTHER FRONT TO
QUICKLY FOLLOW TUESDAY NIGHT INTO WEDNESDAY ALONG THE SAME PATH. THE
WINDS AND PRECIPITATION WILL BE OF A LESSER EXTENT.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 120 130 132 150 155 172 175 176
FIRE WEATHER...NONE

JN JAN 07