Small Craft Advisory 957, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM AKST TUE DEC 2 2008

.MODEL DISCUSSION...ECMWF/UKMET INITIALIZED BEST WITH LOW COMPLEX
OVER THE NORTH PACIFIC. THE MAIN 950S CENTER SOUTH OF THE ALEUTIANS
IS HANDLED RELATIVELY WELL BY ALL MODELS. THE DIFFERENCES IN
SOLUTIONS OCCUR WITH THE TIMING OF THE NEXT WAVE MOVING OUT OF THE
NORTH PACIFIC COMPLEX. THE ECMWF/UKMET SHOWS A FASTER TRACK AND
PLACES A 970S CENTER JUST NORTH OF THE AK PEN WED AFTERNOON. THE GFS
AT THAT TIME HAS THE LOW SOUTH OF THE AK PEN A SOMEWHAT FURTHER EAST.
STRONG NORTH PACIFIC JET WOULD FAVOR THE FASTER ECMWF MOVEMENT. SINCE
THERE IS NO PERFECT SOLUTION...WILL BLEND THE SHORT TERM GRIDS WITH
THE 12Z ECMWF AND WILL TRANSITION BLEND TOWARD THE GFS AFTER THU
EVENING. REGARDLESS WHAT SOLUTION VERIFIES...WARMER AND WETTER
WEATHER IS IN STORE FOR THE MAINLAND OVER THE NEXT COUPLE OF DAYS.

.UPPER LEVELS...THE RIDGE EXTENDING FROM THE NE PACIFIC TO OVER THE
SW MAINLAND SHIFTS EAST AS THE TROUGH ALONG 170W SLOWLY TRANSLATES
EAST. AS THE RIDGE RETREATS AND THE TROUGH MOVES EAST...EXPECT MUCH
OF THE GULF AND SOUTH MAINLAND TO COME UNDER SOUTHERLY FLOW. THIS
WILL TRANSLATE INTO WETTER AND WARMER WEATHER. BY WED...A HIGH
AMPLITUDE RIDGE IS EVIDENT OVER THE WESTERN BERING SEA AND CONTINUES
THROUGH THE LATTER PART OF THIS WEEK.

.SHORT TERM FORECAST...
.EAST...A WEATHER FRONT OVER KODIAK ISLAND THIS AFTERNOON CONTINUES
TO THE NORTHERN AND EASTERN GULF TONIGHT. EXPECT SNOW WITH THIS
SYSTEM ALONG THE NORTH GULF COAST AND SE EXPOSURES OF SOUTH CENTRAL
ALASKA. THE NEXT FRONT MOVES NORTH AND SPREADS ADDITIONAL MOISTURE TO
SOUTHCENTRAL AND NORTHERN GULF WED/THU AS WAVE HEADS INTO THE EASTERN
BERING SEA. SHOULD SEE SIGNIFICANT WARMING WITH THIS FRONT WITH A
TRANSITION FROM SNOW A MIX INLAND AND A MIX TO RAIN ALONG THE COASTS
THU. ALSO EXPECT FAIRLY STRONG SE WINDS IN ADVANCE OF FRONT WITH
STRONG GAP WINDS OVER SOUTHCENTRAL WED. WINDS WILL WEAKEN OVER THE
GULF THU...BUT GAP WINDS LIKELY TO HOLD OVER SOUTHCENTRAL WITH A
SURFACE LOW HOLDING IN THE EASTERN BERING SEA.

.WEST...
.SW MAINLAND...A WEAK FRONTAL WAVE OVER THE CENTRAL ALEUTIANS
CONTINUES NORTH AND WEST AND WEAKENS TONIGHT AS THE FRONT MOVES INTO
THE SW INTERIOR. WARMER AIR BEHIND THIS SYSTEM WILL SET THE STAGE FOR
A TRANSITION FROM SNOW TO MIXED PRECIPITATION AS THE NEXT WEATHER
FRONT MOVES NORTH OF THE AK PEN/EAST ALEUTIANS EARLY WED. AS STATED
EARLIER...THE MODELS SHOW A SIGNIFICANT DIFFERENCE IN THE TIMING OF
THE WAVE MOVING NORTH OF THE AK PEN. THIS DIFFERENCE AND SUBSEQUENT
SOLUTIONS WILL HAVE A MAJOR IMPACT ON SENSIBLE WEATHER FORECAST. THE
ECMWF WOULD SUGGEST WARMING OVER MUCH OF SW AK WITH THE TROUGH AXIS
WEST OF THE MAINLAND. WHILE THE GFS HOLDS THE TROUGH AXIS OVER THE
MAINLAND...KEEPING THE DELTA IN THE COLDER AIR AND BRISTOL BAY IN THE
WARM AIR THROUGH THU NIGHT. FOR NOW WILL GO WITH A BLEND OF THE 12Z
ECMWF AND EXISTING GRIDS THROUGH THU EVENING AND THEN TRANSITION TO
THE GFS AFTERWARD.

.ALEUTIANS/AK PEN..EASTERN BERING SEA...

WINDY CONDITIONS WILL HOLD FOR THE NEXT COUPLE OF DAYS. WAVE
APPROACHING THE AK PEN TONIGHT WILL BRING ANOTHER ROUND OF SOUTHERLY
GALES/STORMS EAST OF 170W TONIGHT. WINDS SHOULD DIMINISH AND BECOME
GENERALLY SOUTHERLY AFTER WAVE PASSAGE WED OVER THE AK PEN. THESE
CONDITIONS WILL LIKELY HOLD THROUGH THU NIGHT. STRONG NORTH TO NE
WINDS WEST OF 170W WILL CONTINUE THROUGH THU NIGHT AS LOW COMPLEX
SOUTH OF THE EASTERN ALEUTIANS DRIFTS EAST.

.LONG TERM FORECAST...

THE MODEL ARE IN GENERAL AGREEMENT IN TO NEXT WEEK. HIGH PRESSURE
CONTINUES BUILDING OVER THE CENTRAL BERING SEA. WHILE A DEVELOPING
NORTH PACIFIC LOW DEEPENS AND MOVE INTO THE THE SOUTHERN GULF OF
ALASKA BY MONDAY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...STORMS 155 185
GALES 120 125 130 132 138 140 150 160 165 170 171 172 175 176 180.

RMC DEC 08