Small Craft Advisory 79, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AKST WED JAN 21 2009

.MODEL DISCUSSION...12Z EUROPEAN MODEL AND 00Z GFS ARE IN DECENT
AGREEMENT THROUGH 84 HOURS. THE 00Z EUROPEAN CAME IN WITH A
SIGNIFICANTLY DIFFERENT TRACK FOR THE LOW IN THE BERING SEA
FRIDAY...AND WAS NOT CONSIDERED IN THE MORNING FORECAST. THE GFS WAS
USED IN THE SHORT TERM...TRANSITIONING TO THE 12Z EMCWF FOR THE MID
AND LONG RANGE FORECASTS.

.ANALYSIS AND UPPER LEVELS...
A LOW IN THE CENTRAL BERING SEA IS WEAKENING AND DRIFTING NORTH. A
HIGHLY AMPLIFIED TRANSIENT RIDGE IS OVER WESTERN ALASKA AND MOVING
TOWARD THE EAST. A 120KT SOUTHERLY JET IS BRINGING MOIST FLOW INTO
THE THE EASTERN BERING SEA FROM AS FAR SOUTH AS 35N. A 1050 MB
SURFACE HIGH CENTERED NEAR BARROW IS KEEPING SKIES CLEAR OVER MUCH OF
MAINLAND ALASKA. AS THIS HIGH MOVES SOUTHEAST TOWARD CANADA IT IS
HELPING SQUEEZE THE PRESSURE GRADIENT OVER THE WESTERN HALF OF THE
STATE WITH THE HELP OF LOW PRESSURE IN THE BERING SEA. GAP WINDS IN
SOUTHCENTRAL HAVE ALSO ALREADY BEGUN TO PICK UP AS HIGH PRESSURE
SKIRTS THE AREA. VALDEZ AIRPORT HAS SEEN GUSTS ABOVE 40 MPH EARLY
THIS MORNING...WHILE PARTS OF WESTERN ALASKA HAVE ALSO BEEN GUSTING
INTO THE 30 TO 40 MPH RANGE.

.SHORT TERM FORECAST...
.SOUTHCENTRAL...MAIN CHALLENGE TODAY WILL BE FOG/STRATUS DISSIPATING
TIMES AND WIND SPEEDS THROUGH FAVORED AREAS SUCH AS THOMPSON
PASS/VALDEZ ARM AND THE COPPER RIVER DELTA. WINDS IN VALDEZ SHOULD
PEAK AROUND MIDDAY BEFORE LIMITED UPPER SUPPORT MOVES OFF TO THE
EAST...HOWEVER SURFACE GRADIENT WILL REMAIN TIGHT SO WINDS SHOULD
REMAIN GUSTY THROUGH LATE THIS EVENING AND INTO THE OVERNIGHT HOURS.
FOG AND STRATUS COVERAGE SHOULD CONTINUE ON A DOWNWARD TREND...AND
SHOULD BE LARGELY GONE BY MID MORNING AS LIGHT TO MODERATE WINDS PICK
UP ACROSS THE AREA AND HIGH PRESSURE MOVES TO THE EAST.

.WEST OF THE ALASKA RANGE...STRONG WINDS WILL CONTINUE TO SPREAD INTO
THE DELTA AND BRISTOL BAY ZONES TODAY ASSOCIATED WITH THE WEAKENING
FRONT MOVING ONSHORE. PRECIP DOES NOT LOOK OVERLY IMPRESSIVE ANYMORE
WITH THIS FRONT...DESPITE TROPICAL CONNECTIONS. MAIN BAND OF PRECIP
WILL BE MOVING THROUGH COLD BAY THIS MORNING HEADING NORTH AND EAST.
COLD NORTHERLY FLOW WILL CONTINUE IN THE WESTERN ALEUTIANS. IT IS
WORTH NOTHING THAT DEPENDING ON THE EXACT TRACK AND INTENSITY OF THE
LOW IN THE BERING ON FRIDAY BRISTOL BAY AND THE DELTA COULD BE IN FOR
A HIGH WIND EVENT...THOUGH MODEL UNCERTAINTY YIELDS LOW CONFIDENCE AT
THIS TIME.

.LONG TERM FORECAST...DESPITE THE DISAGREEMENT IN THE LONG RANGE
MODELS...THE GFS SEEMS TO BE TRENDING TOWARD THE ECMWF SOLUTION A
BIT. THE ECMWF HAS BEEN HINTING FOR SEVERAL RUNS NOW AT A RIDGE
BUILDING NEXT WEEK IN THE BERING SEA AND EXTENDING NORTHWEST BEYOND
SIBERIA. FOR THE TIME BEING...TEMPERATURES SHOULD RETURN TO NORMAL
LEVELS...WITH THE POSSIBILITY OF A MAJOR PATTERN SHIFT BEGINNING
EARLY NEXT WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE WARNING 130 138 140 150 155 160 180
         HEAVY FREEZING SPRAY WARNING 160
FIRE WEATHER...

AMD JAN 09