Gale Warning 230, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AKST WED MAR 4 2009

.MODEL DISCUSSION...

MODELS SEEM TO BE HAVING A GOOD HANDLE ON ALL FEATURES IN THE SHORT
TERM.  THE GFS WAS THE PREFERRED MODEL THIS EVENING...BUT THE 00Z
NAMS SOLUTION OF A SLIGHTLY STRONGER TROUGH IN THE GULF NEEDS TO BE
WATCHED FOR THE REASON OF POSSIBLY PREVENTING THE TRANSPORT OF WARMER
AIR INTO ANCHORAGE FROM TURNAGAIN ARM WEDNESDAY NIGHT INTO THURSDAY.
THE PREFERRED GFS HAS BEEN WEAKER WITH THIS TROUGH ...LIKELY MEANING
WARMER TEMPERATURES MAKING IT INTO THE ANCHORAGE BOWL FOR THE LATE
WEDNESDAY THROUGH THURSDAY PERIOD.

.ANALYSIS AND UPPER LEVELS...

SURFACE HIGH PRESSURE IS CURRENTLY LOCATED NEAR TOK THIS
MORNING...WITH THE UPPER RIDGE AXIS JUST WEST OF THE ALASKA RANGE.
THIS IS HELPING TO FUNNEL SLIGHTLY COOLER THAN EXPECTED AIR SOUTHWARD
INTO SOUTHCENTRAL ALASKA.  A STRONG WARM FRONT IS MOVING NORTHWARD
EXTENDING FROM THE CENTRAL BERING SEA THROUGH BRISTOL BAY TO JUST
SOUTH OF KODIAK ISLAND.  STRONG WARM ADVECTION IS PROVIDING STRONG
LIFT OVER THE BERING SEA AND SOUTHWEST ALASKA THIS MORNING ALONG AND
AHEAD OF THE WARM FRONT.  THIS FRONT EXTENDS ALL THE WAY BACK TO THE
SOUTH AND WEST TO A 976 MB LOW APPROACHING THE WESTERN ALEUTIANS FROM
THE SOUTH.  THIS LOW IS BRINGING STRONG WINDS TO STORM FORCE NEAR THE
TRACK OF THE LOW...WITH GALES OVER A GOOD PORTION OF THE BERING SEA
AND ALEUTIANS THIS MORNING.  ON THE BACKSIDE...BLIZZARD CONDITIONS
HAVE BEEN OCCURRING IN THE WESTERN ALEUTIANS.  A STRONG NEGATIVE TILT
UPPER TROUGH IS ASSOCIATED WITH THIS SURFACE LOW OVER THE WESTERN
ALEUTIANS CURRENTLY...WITH A STRONG SOUTHERLY JET SERVING AS A STRONG
CONVEYOR BELT OF WARM MOIST AIR INTO SOUTHWESTERN ALASKA BETWEEN THE
TROUGH AND UPPER RIDGE OVER SOUTHERN ALASKA.

.SHORT TERM FORECAST...

WEST OF THE ALASKA RANGE...THE STRONG WARM FRONT WILL CONTINUE TO
PUSH ACROSS THE MAINLAND OF SOUTHWEST ALASKA DURING THE DAY
TODAY...LIKELY BRINGING A MIXED BAG OF PRECIPITATION TO THE REGION.
WITH THE WARM AIR MOVING IN ALOFT OVER SUB-FREEZING TEMPERATURES AT
THE SURFACE...EXPECT TO SEE FREEZING RAIN DEVELOP FROM DILLINGHAM TO
KING SALMON...WITH A CHANGEOVER FROM SNOW TO FREEZING RAIN FARTHER
NORTH OVER THE KUSKOKWIM DELTA.  FARTHER INLAND INTO THE UPPER
KUSKOKWIM VALLEY EXPECT A LONGER PERIOD OF SNOW...BUT EVEN LOCATIONS
AS FAR NORTH AS MCGRATH WILL LIKELY SEE A PERIOD OF FREEZING RAIN AS
WELL.  HEAVIEST SNOW ACCUMULATIONS WILL BE SEEN THE FARTHER NORTH AND
EAST ONE GOES...SINCE THE CHANGEOVER WILL BE DELAYED A BIT LONGER IN
INLAND LOCATIONS. AS THE LOW LIFTS NORTH TOWARDS THE BERING STRAIT
TONIGHT THE NEXT BIG ISSUE WILL BE THE STRENGTH OF THE WINDS THROUGH
THE BERING SEA AND ALONG THE COASTLINE OF THE DELTA REGION WEDNESDAY
NIGHT AND EARLY THURSDAY.

AS THE CURRENT SYSTEM DEPARTS THURSDAY...HIGH PRESSURE BUILDS ACROSS
THE EASTERN ALEUTIANS INTO SOUTHWEST ALASKA THROUGH FRIDAY...BUT ONLY
TEMPORARILY AS THE NEXT BIG NORTH PACIFIC LOW MOVES NORTH INTO THE
ALEUTIANS BY FRIDAY NIGHT BRINGING WINDS TO GALE FORCE AND ANOTHER
ROUND OF PRECIPITATION TO CENTRAL AND WESTERN ALEUTIANS.

SOUTH AND EAST OF THE ALASKA RANGE...EXPECTING A SIGNIFICANT WINTER
WEATHER EVENT ESPECIALLY FOR INTERIOR SECTIONS OF SOUTHERN ALASKA. AS
THE WARM FRONT LIFTS NORTH THROUGH SOUTHCENTRAL TODAY EXPECT A ROUND
OF OVERRUNNING PRECIPITATION TO SWEEP NORTH AND EAST...BRINGING LIGHT
SNOW TO MOST LOCATIONS IN THE REGION.  FOR THE SUSITNA VALLEY...LIFT
LOOKS QUITE IMPRESSIVE FOR THIS EVENT...SO EXPECTING THE HIGHEST
PRECIPITATION AND SNOW AMOUNTS THERE...ESPECIALLY NORTH OF
TALKEETNA...WITH RAIN POSSIBLY MIXING IN FROM TALKEETNA SOUTH FOR AT
LEAST A PART OF THE EVENT ON THURSDAY.  FOR ANCHORAGE...THERE SHOULD
BE A GOOD ROUND OF OVERRUNNING PRECIPITATION THIS EVENING...FOLLOWED
BY AN INCREASE IN WINDS PROVIDING GOOD MIXING TO RAISE TEMPERATURES
INTO THE 30S THURSDAY WITH RAIN OR FREEZING RAIN POSSIBLY MIXED WITH
SNOW. AFTER THE FRONT PASSES THROUGH...COLD ADVECTION TAKES OVER
BEFORE THE UPPER TROUGH PASSES THROUGH...LIKELY ALLOWING FOR A BRIEF
CHANGEOVER BACK TO SNOW BEFORE PRECIPITATION ENDS EARLY FRIDAY.  SO
FAR...MODELS HAVE NOT DEVELOPED A NORTHERN GULF OR PRINCE WILLIAM
SOUND LOW AS THE BEST DYNAMICS AND BEST LIFT ARE FARTHER NORTH AND
INLAND.  BECAUSE OF THIS...THERE IS A CHANCE THAT THE COPPER RIVER
BASIN COULD EXPERIENCE ADVISORY LEVEL WINTER WEATHER CRITERIA
THURSDAY INTO LATE FRIDAY AS THE FRONT MOVES ACROSS THE AREA.

.LONG TERM FORECAST...

HIGH PRESSURE BUILDS ACROSS THE STATE FROM THE SOUTH AND WEST FOR THE
WEEKEND...WITH ANOTHER NORTH PACIFIC LOW MOVING INTO THE BERING SEA
DURING THE DAY ON SATURDAY.  THE PATTERN APPEARS TO BECOME HIGHLY
AMPLIFIED EARLY TO MID WEEK NEXT WEEK AS THE UPPER RIDGE POSSIBLY
BUILDS ALL THE WAY TO THE NORTH POLE...BLOCKING THE LOW PRESSURE
SYSTEM OVER THE ALEUTIANS AND CREATING STRONG SOUTHERLY FLOW INTO THE
SOUTHERN HALF OF THE STATE...ESPECIALLY WEST OF THE ALASKA RANGE.
THUS...EXPECT THE WARMEST TEMPERATURES OUT WEST WITH THE BEST
PRECIPITATION CHANCES...WITH COOLER TEMPERATURES AND DRIER WEATHER
TOWARDS THE ALCAN BORDER.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...WINTER STORM WATCH...145
         BLIZZARD WARNING...191
MARINE...GALE WARNING...160 165 170 171 179 180 185
         STORM WARNING...172 175 176
         HEAVY FREEZING SPRAY ADVISORY...185
FIRE WEATHER...NONE.

CC MAR 09