Small Craft Advisory 816, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM AKDT WED OCT 7 2009

.MODEL DISCUSSION...GFS/ECMWF/NAM MSLP AND MOISTURE INITIALIZATIONS
AND FORECAST TREND THROUGH FRI AFTERNOON ARE REASONABLE AND IN FAIR
AGREEMENT. THE GFS/ECMWF ARE NOW IN BETTER AGREEMENT THROUGH SAT
AFTERNOON AS THE GFS HAS SLOWED THE PROGRESSION OF DEVELOPING STORM
APPROACHING THE AK PEN FRI EVENING.

.UPPER LEVELS...
CURRENT SATELLITE IMAGERY SHOWS RIDGING OVER THE GULF OF ALASKA AND
THROUGH THE CENTRAL MAINLAND WITH A LONG WAVE TROUGH EXTENDING FROM
EASTERN RUSSIA TO OVER THE NE PACIFIC. TROUGH CONTAINS TWO MAIN
CENTERS...A WEAKENING ONE OVER THE BERING SEA AND A STRONGER CENTER
SOUTH OF THE CENTRAL ALEUTIANS. COLD ADVECTION IS EVIDENT SOUTH OF
THIS LOW WITH THE PRESENCE OF OPEN CELL CUMULUS. A STRONG WESTERLY
JET IS EVIDENT ACROSS THE NORTH PACIFIC WITH MOIST SOUTHERLY FLOW
BETWEEN 150-165W.

RIDGE OVER THE GULF AND MAINLAND SHIFTS TO BETWEEN 130-140W SAT. LOW
CENTER OVER THE BERING SEA WEAKENS AND MOVES SW AS LOW CENTER SOUTH
OF THE ALEUTIANS MOVES TO THE CENTRAL BERING SEA ON FRI AFTERNOON.
SECONDARY DEVELOPMENT OVER THE NORTH PACIFIC LIKELY AS COLD ADVECTION
DIGS OUT THE BASE. DEVELOPING CENTER MOVES JUST SOUTH OF THE AK PEN
ON FRI EVENING AND OVER WESTERN BRISTOL BAY EARLY SAT. EXPECT STRONG
SOUTHEASTERLY FLOW OVER THE GULF FRI NIGHT...SPREADING TO THE
MAINLAND SAT.

.SHORT TERM FORECAST...
.EAST...ONLY A FEW OVERALL ADJUSTMENTS WILL BE MADE TO THE SHORT TERM
FORECAST PACKAGE THIS AFTERNOON. WARM FRONTAL BOUNDARY MOVES NORTH
THRU TODAY AS SOUTHERLY FLOW INTENSIFIES IN THE MID LEVELS. OCCLUDED
FRONT APPROACHING THE AK PEN MOVES INLAND OVER WESTERN ALASKA TONIGHT
AS TRAILING COLD FRONT STALLS OVER THE WESTERN GULF TONIGHT THEN
WEAKENS AS IT TRACKS EAST THU NIGHT. FREEZING LEVELS WILL INCREASE
AND REMAIN RELATIVELY HIGH ACROSS THE GULF AND SOUTHCENTRAL OVER THE
NEXT COUPLE OF DAYS WITH GENERALLY WARM SOUTHERLY FLOW ALOFT. SO
PRECIPITATION WILL BE MAINLY RAIN...EXCEPT OCCASIONALLY MIXED AT
HIGHER ELEVATIONS. PRESSURE GRADIENTS ARE EXPECTED TO INCREASE ACROSS
SOUTHCENTRAL ALASKA THROUGH TONIGHT...SO WILL SEE INCREASING WINDS
OVER THE GULF AND STRONG GAP FLOWS ACROSS SOUTHCENTRAL. A DEVELOPING
LOW OVER THE NORTH PACIFIC MOVES TO NEAR CHIGNIK EARLY SAT AND WILL
BRING INCREASED RAINS AND WINDS ACROSS SOUTHCENTRAL AND STORMS ACROSS
THE GULF. MAY SEE WINDS APPROACHING WARNING LEVELS LATE FRI NIGHT AND
SAT IN ZONES 101/125.

.WEST...LOW OVER THE BERING SEA IS SLOWLY WEAKENING AND MOVING SW.
OCCLUDED FRONT MOVING INTO BRISTOL BAY THIS AFTERNOON IS SPREADING
RAIN AND GUSTY WINDS INTO SOUTHWEST ALASKA. OCCLUDED FRONT MOVES
THROUGH SW ALASKA TONIGHT. 970S LOW SOUTH OF THE ALEUTIANS THIS
AFTERNOON MOVES NORTH OF THE CENTRAL ALEUTIANS THU AND INTO THE
CENTRAL BERING SEA AND WEAKENS FRI EVENING. ASSOCIATED FRONT MOVES
INTO THE AK PEN AND SW ALASKA THU MORNING...THEN WEAKENS AND SHIFTS
EAST. DEVELOPING LOW OVER THE NORTH PACIFIC MOVES TO NEAR CHIGNIK
EARLY SAT AND WILL BRING INCREASED RAINS AND WINDS ACROSS SW ALASKA
LATE FRI NIGHT THROUGH SAT. MAY SEE WARNING LEVEL WIND GUSTS THROUGH
GAPS IN THE ALEUTIANS RANGE AND BRISTOL BAY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALES 130,132,150,155,165,170,171,176,179,AND 185.
FIRE WEATHER...NONE.

RMC OCT 09