Gale Warning 670, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM AKDT TUE SEP 29 2009

.MODEL DISCUSSION...IN THE SHORT TERM (THROUGH SATURDAY) THE MODELS
MATCH EACH OTHER FAIRLY WELL BOTH IN STRENGTH AND TIMING OF THE MAIN
FEATURES MOVING EASTWARD IN THE PROGRESSIVE FLOW ACROSS THE ALEUTIANS
AND SOUTHERN ALASKA.

SHORT TERM...WEAK LOW JUST OFF THE EAST COAST OF KODIAK ISLAND IS A
TRIPLE POINT THAT DEVELOPED ALONG THE WASHED OUT FRONT THAT IS COMING
ACROSS SOUTHCENTRAL TODAY. ANCHORAGE 12Z RAOB SHOWS THE FREEZING
LEVEL AT 168 FT. WARMING ASSOCIATED WITH THE FRONT NOT ALL THAT MUCH
BUT ENOUGH TO PUT THE SNOW LEVEL IN THE 800 TO 1200 FT RANGE LATE
THIS AFTERNOON..LOWERING SOME OVER NIGHT. SOUTHWEST WIND FLOW BEHIND
TODAYS FRONT WILL KEEP SKIES CLOUDY WITH OCCASIONAL SNOW..LIGHT
SNOW..ABOVE THE 500 OR 800 FT LEVEL THROUGH WEDNESDAY MORNING. WET
SNOW COULD REACH THE LOWEST ELEVATIONS OVERNIGHT BUT AGAIN IT WILL BE
LIGHT WITH VERY LITTLE IF ANY ACCUMULATION.

DEVELOPING FRONTAL WAVE SOUTH OF THE ALASKA PENINSULA TO SLOWLY
STRENGTHEN AND MOVE TO JUST EAST OF PADQ TONIGHT. THIS LOW WILL MOVE
TO 100 NM SOUTHWEST OF YAKUTAT LATE WED NIGHT. TO THE WEST OF THIS
SYSTEM THE PRESSURE  GRADIENT WILL BECOME SIGNIFICANT ENOUGH FOR A
WIDESPREAD NW WIND WITH GALES KODIAK ILSE AND THE WESTERN GULF.
COOLER DRIER AIR WILL RIDE IN ON THESE WINDS BEGINNING WEDNESDAY
AFTERNOON. AT THIS POINT THE VERY COLD TEMPERATURES NOW ACROSS
NORTHERN ALASKA WILL STAY UP THERE SINCE THE UPPER LEVEL HIGH STAYS
PRETTY FLAT.

ANOTHER TYPICAL FALL STORM WILL MOVE INTO THE WESTERN ALEUTIANS WED
NIGHT AND THURSDAY WITH A FULL GALE ALONG AND IN ADVANCE OF THE
FRONT. THAT FRONT IS EXPECTED TO REACH THE SOUTHWEST COAST FRIDAY
MORNING AND REMAIN STRONG ENOUGH FOR MINIMUM GALES.

.LONG TERM FORECAST...MODELS HAVE BEEN VERY CONSISTENT SINCE LAST
SATURDAY IN BUILDING STRONG UPPER HIGH PRESSURE IN THE NORTHEAST
PACIFIC WITH THE RIDGE AXIS ALONG 140W OR SO. THE FORECAST AREA EAST
OF 160W WILL FALL UNDER A STRONG SOUTHWEST FLOW WITH THE AREA FROM
KODIAK ISLAND WEST TO UNALASKA GETTING THE HEAVIEST RAIN AND
STRONGEST WINDS. HOW MUCH EFFECT THESE FRONTS WILL HAVE ON THE NORTH
GULF COAST AND ZONE 141 AS WELL AS SOUTHCENTRAL ALASKA DEPENDS ON THE
EXACT DAY TO DAY POSITION OF THE JET. THE LONG WAVE PATTERN LOOKS
GOOD THE NEXT 7 DAYS BUT AS ALWAYS TIMING AND TRACK OF THE INDIVIDUAL
STORMS IS ALWAYS IN DOUBT.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE AREAS 132..150..155..165..170..179.
FIRE WEATHER...NONE

DPERCY SEP 09