Small Craft Advisory 239, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM ADT MON MAR 17 2008

.ANALYSIS AND UPPER LEVELS...
A BROAD AREA OF LOW PRESSURE IS CENTERED IN THE NORTHERN GULF OF
ALASKA. WITH THE JET STREAM NOW WELL TO THE SOUTH OF THE FORECAST
AREA...THE LOW HAS LOST MUCH OF ITS UPPER SUPPORT AND WILL REMAIN
NEARLY STATIONARY THROUGH WEDNESDAY. A POTENT SHORTWAVE IS DROPPING
SOUTHWARD ON THE BACKSIDE OF THIS LOW. THE SHORTWAVE HAS ENHANCED
SNOW SHOWER ACTIVITY IN THE EASTERN BERING SEA AND BROUGHT BLIZZARD
CONDITIONS TO THE PRIBILOF ISLANDS SUNDAY EVENING AND THE ALASKA
PENINSULA MONDAY MORNING. THIS SHORTWAVE WILL CROSS OVER THE ALASKA
PENINSULA MONDAY NIGHT AND MERGE WITH THE DOMINANT GULF UPPER LOW.
FURTHER WEST...A SERIES OF LOW PRESSURE SYSTEMS WILL RACE ALONG THE
ALEUTIAN CHAIN AND INTO THE GULF BY WEDNESDAY.

.MODEL DISCUSSION...
GFS CONTINUES TO SHOW REMARKABLE CONSISTENCY THROUGH WEDNESDAY NIGHT.
AS SUCH...THE FORECAST PACKAGE LEANS HEAVILY ON THE 00Z GFS RUN. THE
NUMERICAL MODELS CONTINUE TO STRUGGLE WITH THE HANDLING OF A SERIES
OF LOWS TRAVERSING ALONG THE ALEUTIAN CHAIN AND INTO THE GULF OF
ALASKA. THE LAST FEW RUNS OF THE GFS HAVE BEEN TRENDING TOWARDS A
DEEP COMPLEX LOW PRESSURE SYSTEM IN THE CENTRAL GULF...FAR ENOUGH
AWAY FROM THE MAINLAND TO MINIMIZE PRECIPITATION EFFECTS. GFS
ENSEMBLES ARE STILL SHOWING A WIDE SPREAD...SO THERES STILL A FAIR
AMOUNT OF UNCERTAINTY TOWARDS THE WEEKEND.

.SHORT TERM FORECAST...
SOUTH AND EAST OF ALASKA RANGE...
REMNANTS OF NORTHERN GULF OF ALASKA LOW PRESSURE WILL BE PROVIDE
HIT-OR-MISS SNOW SHOWERS THROUGH WEDNESDAY. TODAY...THE FLOW REMAINS
PRIMARILY OFFSHORE SO EXPECTING CONDITIONS TO REMAIN PRIMARILY DRY.
BEST CHANCE FOR SNOW IN ANCHORAGE IS LOOKING TO BE TUESDAY NIGHT INTO
WEDNESDAY AS AN UPPER SHORTWAVE SWINGS AROUND...THOUGH THE FORECAST
WILL NOT REFLECT MORE THAN A CHANCE AT THIS POINT. WEATHER OTHERWISE
LOOKS RELATIVELY STAGNANT THE NEXT FEW DAYS WITH PARTLY TO MOSTLY
CLOUDY SKY CONDITIONS.

SOUTHWEST MAINLAND...
NORTH-SOUTH ORIENTED SHORTWAVE IS CAUSING AN ABUNDANCE OF WEATHER FOR
A NUMBER OF LOCALITIES THIS MORNING. GUSTY NORTH WINDS CAN BE
EXPECTED TO CONTINUE ALONG THE KUSKOKWIM COAST AND THE ALASKA
PENINSULA UNTIL THE SHORTWAVE PASSES THROUGH TONIGHT. SNOW AND
BLOWING SNOW WILL BE A PROBLEM WITH THIS FEATURE IN THE SHORT
TERM...BUT NOT EXPECTING BLIZZARD CONDITIONS OUTSIDE OF THE AKPEN.
AFTER THIS SHORTWAVE PASSES BY...PROTOTYPICAL COLD ADVECTION SNOW
SHOWERS CAN BE EXPECTED TO CONTINUE ALONG THE AKPEN AND COASTAL AREAS
FOR THE FORESEEABLE FUTURE.

ALEUTIANS AND BERING SEA...
HIGH PRESSURE STEMMING OFF OF THE COLD SIBERIAN LANDMASS WILL REMAIN
FIRM OVER THE WESTERN BERING SEA THE NEXT SEVERAL DAYS. THIS WILL
KEEP COLD NORTHERLY FLOW AND ITS ASSOCIATED SNOW SHOWERS AND BLOWING
SNOW OVER THE CENTRAL AND EASTERN BERING. TWO QUICK MOVING LOW
PRESSURE SYSTEMS WILL MOVE ALONG THE ALEUTIAN CHAIN THIS WEEK...EACH
BRINGING A QUICK CHANCE OF RAIN AND SNOW.

.LONG TERM FORECAST...
LONG TERM MODELS ARE STILL FORECASTING A MEAN LONGWAVE TROUGH IN THE
CENTRAL GULF OF ALASKA AND RIDGE OVER THE WESTERN BERING SEA NEXT
WEEKEND. THIS SCENARIO WOULD LEAD TO A GENERALLY COLD AND DRY SETUP
FOR THE ALASKA MAINLAND.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 181.
MARINE...GALE 130 150 155 165
         HEAVY FREEZING SPRAY 179 185 412 414
FIRE WEATHER...NONE.

*** MAR 08