Small Craft Advisory 1032, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
300 PM AST FRI DEC 9 2005

.DISCUSSION...THE WEATHER FEATURE THAT HAS BROUGHT A LOT OF ACTION TO
THE STATE THE LAST FEW DAYS IS NOW A 975 MB LOW NEAR THE SEWARD
PENINSULA THAT CONTINUES TO MOVE NORTHWARD. COLD AIR WILL BEGIN TO
MOVE BACK INTO SOUTHWESTERN ALASKA TONIGHT AND SATURDAY AROUND THE
SOUTH SIDE OF THIS LOW. THE COLD AIR WILL THEN CROSS THE ALASKA RANGE
BY SATURDAY NIGHT.

THE BIG WEATHER FEATURE TODAY HAS TO DO WITH A 980 MB LOW IN THE
WESTERN GULF OF ALASKA THAT WILL MOVE INTO PRINCE WILLIAM SOUND
TONIGHT. THIS LOW WILL RAPIDLY WEAKEN TONIGHT AS THE SUPPORTING JET
STREAM STARTS WELL SOUTH OF THE AREA AND IS HEADING INTO THE ALASKA
PANHANDLE. THE MAJORITY OF THE WARM AIR AND ENERGY FROM THIS SYSTEM
WILL GO THERE...BUT THIS SYSTEM WILL STILL HAVE AN IMPACT ON SOUTH
CENTRAL ALASKA AS WELL.
THE LOW CENTER HAS ENTRAINED SOME WARM AIR INTO IT AND THE GENERAL
ENVIRONMENT OF SOUTHERN ALASKA IS WARM. AS A RESULT THE PRECIPITATION
AT THE BEGINNING OF THE SYSTEM WILL BE RAIN. TEMPERATURES THAT
REACHED INTO THE 40S...AND EVEN LOWER 50S...IN THE DOWNSLOPE CHINOOK
WINDS THROUGH THURSDAY THROUGH THIS MORNING HAVE DROPPED BACK INTO
THE 30S OVER MOST OF THE AREA. THOUGH 850 MB TEMPERATURES OVER SOUTH
CENTRAL THROUGH SATURDAY NIGHT ARE ONLY BETWEEN -2 AND -4 C...WHICH
NORMALLY INDICATE RAIN OR A RAIN SNOW MIX...THERE ARE INDICATIONS
THAT SNOWFALL MIGHT BECOME THE RULE OVERNIGHT TONIGHT. THOUGH THE
EARLY PRECIPITATION WILL BE RAIN...IT WILL BE SNOW WHEN IT INITIALLY
LEAVES THE CLOUD. THE EVAPORATIVE COOLING OF THIS CHANGE OF STATE AS
WELL AS THE ENTRAINMENT OF COLDER AIR ALOFT WILL HELP TO COOL THE AIR
COLUMN AND TURN PRECIPITATION TO SNOW OVERNIGHT. THIS IS LIKELY TO
HAPPEN IN ANY PRECIPITATION WEST OF THE ALASKA RANGE AND IN THE
SUSITNA VALLEY. THE FARTHER TO THE SOUTH AND EAST THE LONGER BEFORE
THE SWITCH OCCURS.
THE EXPECTED PRECIPITATION IS EXPECTED TO COME FROM THE SYSTEM
CURRENTLY IN THE GULF AND THEN FROM A NEW LOW THAT WILL DEVELOP NEAR
KODIAK SATURDAY AFTERNOON. THIS NEW LOW WILL BE RELATIVELY WEAK BUT
WILL MOVE UP COOK INLET SATURDAY NIGHT AND THEN DRIFT INTO PRINCE
WILLIAM SOUND SUNDAY. THOUGH THE ATMOSPHERE HAS TO COOL SUFFICIENTLY
AND HAVE HAVE LIFT...THIS WEEKEND COULD SEE SIGNIFICANT SNOWFALL IN
AREAS OF SOUTH CENTRAL ALASKA SHOULD ALL THIS OCCUR.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...SEE CURRENT FORECASTS.
FIRE WEATHER...NONE.

EZ DEC 05