Heavy Freezing Spray Warning 155, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
400 PM AKDT WED APR 11 2012

.ANALYSIS AND UPPER LEVELS...AN UPPER LEVEL HIGH OVER THE INTERIOR OF
THE STATE WILL WEAKEN A LITTLE AND MOVE INTO THE ARCTIC OCEAN LATER
IN THE WEEK. THE JET STREAM IS RUNNING WELL SOUTH OF THE FORECAST
AREA AND IS STRENGTHENING A SURFACE LOW SOUTH OF ATTU. THIS LOW WILL
MOVE EASTWARD THROUGH THE REST OF THE WEEK AND MOVE INTO THE
SOUTHWEST GULF THIS WEEKEND. A SHARP UPPER LEVEL TROUGH OVER THE
BERING SEA WILL DIG SOUTHWARD AND MERGE WITH THE LOW THURSDAY NIGHT.
AT THE SURFACE A STRONG HIGH IS OVER THE WESTERN BERING SEA THAT WILL
PERSIST INTO THE WEEKEND.
THE LOW THAT HAS BROUGHT WEATHER TO THE ALEUTIANS AND ALASKA
PENINSULA IS CONTINUING TO WEAKEN WELL SOUTH OF THE AREA...THOUGH IT
IS STILL CLOSE ENOUGH TO BRING EASTERLY FLOW OVER THE GULF AND SOUTH
CENTRAL ALASKA.
A SERIES OF SHORT WAVES OVER SOUTHEAST ALASKA WILL MOVE NORTHWESTWARD
THROUGH THE REMAINDER OF THE WEEK.

.MODEL DISCUSSION...MODELS ARE DOING VERY WELL. USING THE NAM FOR
DETAIL IN THE EAST. A NAM/GFS BLEND WAS USED FOR THE WESTERN AREAS.
TOWARD THE WEEKEND THE LOW APPROACHING THE SOUTHWEST GULF WILL
ELONGATE AND DEVELOP A SECOND CENTER. THE ECMWF AND NAM BOTH SHOW
THIS FEATURE BUT THE GFS IS CONSOLIDATING THE ENERGY INTO A SINGLE
CENTER WHICH IT OFTEN DOES AND THIS IS NOT LIKELY. THEREFORE THE
ECMWF IS PREFERRED IN THE LONGER TERM.

.SHORT TERM FORECAST...THE FIRST SHORT WAVE HAS BROUGHT SOME MID TO
HIGH LEVEL CLOUDS TO THE NORTH GULF COAST AND SOUTH CENTRAL ALASKA
TODAY. THESE CLOUDS WILL CONTINUE DISSIPATE AS THEY MOVE WESTWARD
INTO THE RIDGE. THE NEXT WAVE ALSO APPEARS TO BE JUST SOME MID LEVEL
CLOUDS AND THE BIGGEST THREAT OF PRECIPITATION WILL BE A FEW SHOWERS
ALONG THE THE NORTH GULF COAST FRIDAY.
A DEFORMATION ZONE EXTENDS FROM JUST EAST OF THE PRIBILOFS THROUGH
THE UNIMAK PASS AREA. THIS IS CONTINUING TO BRING SOME LIGHT SNOW
FROM DUTCH HARBOR THROUGH COLD BAY. TEMPERATURES ARE JUST ABOVE
FREEZING BOTH PLACES SO THE SNOW IS NOT EXPECTED TO ACCUMULATE.

.LONG TERM FORECAST...THE MAIN WEATHER FEATURE AS WE ENTER THE
WEEKEND WILL BE THE LARGE LOW APPROACHING THE SOUTHWEST GULF OF
ALASKA. THE PRECIPITATION WILL BE MOSTLY ALONG THE COAST AND IN THE
FORM OF RAIN. JUST A FEW SHOWERS ARE EXPECTED TO MAKE IT INTO SOUTH
CENTRAL ALASKA AND THE INTERIOR AREAS OF SOUTHWEST ALASKA...THOUGH
THERE MAY BE SOME MIXING WITH SNOW IN AREAS WEST OF THE ALASKA RANGE.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...HEAVY SPRAY 179
FIRE WEATHER...NONE.

APR 12