Small Craft Advisory 1002, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AKST TUE DEC 16 2008

.MODEL DISCUSSION...
MODELS ARE IN VERY GOOD AGREEMENT THIS MORNING OUT THROUGH 60 HOURS.
THE GFS AND THE ECMWF BEGIN TO DIFFER SOMEWHAT AFTER THAT WITH THE
MOVEMENT OF THE NEXT LOW MOVING ALONG THE EASTERN ALEUTIANS AND NEAR
KODIAK FRIDAY BUT SOLUTIONS ARE SIMILAR. THE BIGGEST PROBLEM AFTER
THAT IS THE MOVEMENT OF THE LOW AND FRONT INTO SOUTHEAST.  THE ECMWR
HAS SHOWN GOOD MODEL TO MODEL CONSISTENCY THE PAST DAY OR SO AND ALSO
FOLLOWS HPC GUIDANCE. SO IN THE SHORT TERM THE NAM/GFS WAS USED OUT
TO 60 HOURS FOLLOWED BY THE ECMWF THURSDAY AND BEYOND.

.ANALYSIS AND UPPER LEVELS...
THE LONG WAVE PATTERN CONSISTS OF RIDGE OF HIGH PRESSURE CENTERED
OVER THE STATE WHICH WILL PERSIST THROUGH THE WEEK AND START TO DRIFT
OFF TO THE EAST BY THE WEEKEND. A LONG WAVE TROUGH IS LOCATED OVER
THE KAMCHATKA PENINSULA EXTENDING DOWN THROUGH THE WESTERN BERING
SEA. THIS TROUGH WILL ROTATE EAST AND BE CENTERED OVER THE EASTERN
ALEUTIANS BY THURSDAY FORMING A CLOSED UPPER LOW. THE UPPER JET IS
SPLIT ONE RIDING OVER THE RIDGE WHILE THE SECOND BRANCH RIDES UNDER
THE TROUGH AND INTO THE NORTH PACIFIC AT ABOUT 45N AND THEN UP OVER
RIDGE BY WEDNESDAY NIGHT RESULTING IN THE SPIN UP OF A SURFACE LOW
OVER THE CENTRAL ALEUTIANS MID WEEK. THE SURFACE LOW IS EXPECTED TO
MOVE NEAR KODIAK BY FRIDAY.

.SHORT TERM FORECAST...
SOUTH CENTRAL ALASKA...
AREAS OF FOG WILL CONTINUE TO PERSIST THIS MORNING FROM THE ANCHORAGE
BOWL AND DOWN ALONG COOK INLET EXPECT SOME BREAK FROM THE FOG TODAY
BUT IT WILL RETURN AGAIN TONIGHT. ELSEWHERE CLEAR SKIES WILL
CONTINUE.  AS THE HIGH SHIFTS TO THE EAST AND THE UPPER FLOW BECOMES
SOUTHWESTERLY...CLOUDS WILL INCREASE OVER SOUTHCENTRAL AND WE COULD
SEE A CHANCE OF SOME PRECIPITATION BY WEDNESDAY OTHERWISE EXPECT
MOSTLY DRY CONDITIONS AND TEMPERATURES WARMING SOME.

SOUTHWEST...
A PUSH OF WARM AIR AND MOISTURE MOVE UP ALONG THE WEST COAST AND
BRISTOL BAY TODAY. EXPECT INCREASING CLOUDS TODAY. PRECIPITATION
SHOULD BEGIN ALONG THE COAST LATE THIS AFTERNOON OR EVENING WITH A
RAIN AND SNOW MIX MAINLY ALONG THE COASTAL AREAS AND ALL SNOW INLAND.
AREAS OF MORNING FOG AND MOSTLY CLEAR SKIS OVER THE KUSKOKWIM VALLEY
TODAY WITH INCREASING CLOUDS THIS EVENING AND A CHANCE OF SNOW
TONIGHT WITH LIKELY AREAS OF SNOW ON WEDNESDAY.

ALEUTIANS/ALASKA PENINSULA/BERING SEA...
A LOW WILL PASS OVER THE EASTERN ALEUTIANS TODAY BRINGING ALONG A
LOT OF WARM AIR WITH IT TODAY...EXPECT RAIN TO CONTINUE FALLING OVER
THE ALASKA PENINSULA AND DUTCH HARBOR AREA AND ALSO PUSHING UP OVER
THE PRIBILOFS. OUT WEST THE OLD FRONT ALONG THE WESTERN ALEUTIANS HAS
STALLED AND WINDS AHEAD OF IT HAVE DIMINISHED TO GALES. A LOW WILL
DEVELOP ALONG THE OLD FRONTAL ZONE IN THE NORTH PACIFIC AND CROSS THE
EASTERN ALEUTIANS TUESDAY AFTERNOON BRING MORE RAIN TO THE ALASKA
PENINSULA AND DUTCH HARBOR THROUGH MID WEEK. SNOW SHOWERS WILL
PERSIST OVER THE WESTERN ALEUTIANS WITH THE COLD AIR DROPPING DOWN ON
THE BACKSIDE OF THESE LOWS.

.LONG TERM FORECAST...
LOW PRESSURE MOVING ALONG THE EASTERN ALEUTIANS/ALASKA PENINSULA ON
THURSDAY WILL MOVE NEAR KODIAK BY FRIDAY NIGHT AND SLOWLY DISSIPATES
WHILE A DEVELOPING NORTH PACIFIC LOW ALONG THE ASSOCIATED FRONT WILL
MOVE INTO THE SOUTHEAST GULF OF ALASKA BY SATURDAY. HIGH PRESSURE
WILL BUILD BACK INTO THE GULF ON SUNDAY. AN INTENSE FRONT WILL MOVE
INTO THE WESTERN BERING SEA FRIDAY. A DEVELOPING LOW ALONG THE FRONT
WILL MOVE INTO THE CENTRAL BERING SEA FORMING A BROAD AREA OF LOW
PRESSURE OVER THE BERING BY SUNDAY WHICH WILL CONTINUE TO DRIFT NORTH
AND OUT OF THE AREA BY TUESDAY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALES 160 172 175 176 179 180.
FIRE WEATHER...NONE.

DEC 08