Small Craft Advisory 658, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
300 PM ADT TUE AUG 14 2007

.MODEL DISCUSSION...MODELS IN FAIR AGREEMENT FROM THE 12Z
RUN...HOWEVER THE 18Z NAM HAS SOME INTERESTING CHANGES IN IT. MOSTLY
IT IS DEEPENING THE LOW THAT IS MOVING INTO THE SOUTHWESTERN BERING
SEA LATE TONIGHT AND KEEPS IT A LITTLE STRONGER THAN THE GFS UNTIL
THURSDAY. DATA IS SPARSE IN THE AREA BUT IT LOOKS LIKE THE NAM IS A
LITTLE TOO DEEP AND THE 12Z GFS VALUES ARE MOVE IN LINE WITH THE SHIP
REPORTS IN THAT AREA. THIS WILL CAUSE US TO CONTINUE TO USE THE GFS
SOLUTION OUT WEST AS OPPOSED TO THE NAM.

.ANALYSIS AND UPPER LEVELS...THE MAIN WEATHER FEATURE IS A LOW MOVING
INTO BRISTOL BAY FROM THE NORTHWEST. THIS LOW WILL MOVE OVER THE
NORTHERN KODIAK ISLAND AREA TONIGHT AND THEN INTO THE SOUTHERN GULF
OF ALASKA AFTER THAT. THUNDERSTORMS DEVELOPED EARLY THIS MORNING IN
THE SUSITNA VALLEY AS A FRONT FROM THE BRISTOL BAY LOW MOVED INTO
THIS AREA. THE UPPER LEVEL DIVERGENCE OVER THE SUSITNA VALLEY THAT
HAS PERSISTED TODAY HAS ENHANCED THE LIFTING THERE AND CAUSED THE
THUNDERSTORMS TO PERSIST THROUGH THIS AFTERNOON. THESE STORMS WILL
END LATER IN THE EVENING AS THE UPPER LEVEL DYNAMICS DIMINISH THE
LIFTING WITH THE LOW MOVING TO THE SOUTH OF THE AREA.

.SHORT TERM FORECAST...THUNDERSTORMS IN THE SUSITNA VALLEY WILL
SLOWLY MOVE EASTWARD INTO THE COPPER RIVER BASIN THIS EVENING AND
THEN DIMINISH AS THE LOW MOVES SOUTHEAST AND THE AREA OF ENHANCED
LIFTING DECREASES. RAIN LIKELY FOR MOST OF SOUTH CENTRAL ALASKA
TONIGHT. IN SOUTHWEST ALASKA EXPECT GUSTY WESTERLY WINDS AS THIS LOW
PASSES THROUGH THE AREA.

.LONG TERM FORECAST...AFTER THIS SYSTEM MOVES THROUGH TONIGHT AND
WEDNESDAY THE UPPER LEVEL RIDGE BUILDING IN FROM THE INTERIOR WILL
BRING SOME CLEARING TO SOUTH CENTRAL ALASKA AND PARTS OF SOUTHWESTERN
ALASKA LATER IN THE WEEK. THE SERIES OF LOWS PARADING THROUGH THE
CENTRAL AND WESTERN BERING SEA WILL KEEP RAIN IN THAT AREA. THE
WEATHER FRONTS ASSOCIATED WITH THESE LOWS WILL BRING A CHANCE OF
PRECIPITATION TO THE SOUTHWEST ALASKA COAST LATER THIS WEEK.

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

AUG 07