Gale Warning 651, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM AKDT TUE SEP 22 2009

.MODEL DISCUSSION...
MODELS ARE ALL IN GOOD AGREEMENT THROUGH FRIDAY. BY FRIDAY AFTERNOON
SOLUTIONS FROM THE NAM..GFS..AND ECMWF ARE WITHIN 100 MILES OF EACH
OTHER WITH THE BIG LOW MOVING INTO PRINCE WILLIAM SOUND.  SOLUTIONS
ARE EQUALLY CLOSE FOR OTHER FEATURES SUCH AS THE RIDGE EAST OF THE
LOW AND A SECONDARY LOW IN THE COLD AIR MOVING ACROSS THE BERING SEA.
THE BIG DIFFERENCE IS THE GFS IS MORE AGGRESSIVE IN MOVING THE
SECONDARY LOW AND DOWN STREAM RIDGE ACROSS THE SOUTHERN  BERING.  THE
DIFFERENCE IS MOST APPARENT IN THE GFE RELAXING THE NORTHWEST
GRADIENT OVER THE ALASKA PENINSULA AND SOUTHWEST GULF OF ALASKA
FRIDAY.  OTHERWISE THE MODEL SOLUTIONS FOR TRACK..TIMING AND
INTENSITY ARE VERY CLOSE THROUGH THURSDAY.  TIMING WISE THE GFS
CONTINUES TO BE SLIGHTLY FASTER BUT DIFFERENCES ARE NEGLIGIBLE WITH
THE EXCEPTION OF THE SECONDARY LOW ON FRIDAY MENTIONED ABOVE.

.ANALYSIS AND UPPER LEVELS...
THE MAJOR FEATURE OF INTEREST IS A DEEP LOW SOUTH OF THE WESTERN
ALEUTIANS (REMNANTS OF TYPHOON CHOI-WAN) THAT IS TRACKING EAST ALONG
THE SUBTROPICAL JET. THIS STORM IS FORECAST TO TRACK SOUTH OF THE
ALEUTIANS AS IS MOVES TO JUST EAST OF KODIAK ISLAND BY LATE THURSDAY
AND TO NEAR CORDOVA BY LATE FRIDAY. EXPECT GALE TO STORM FORCE WINDS
AND MODERATE PRECIPITATION TO ACCOMPANY THIS STORM.  A STATIONARY
UPPER LOW JUST INLAND FROM NORTON SOUND WILL SLOWLY WEAKEN AND
DISSIPATE THURSDAY AS THE ALEUTIAN STORM MOVES INTO THE GULF OF
ALASKA.  A LOW IN THE COLD AIR IN THE EXTREME WESTERN BERING IS
FORECAST TO BEGIN TO MOVE SOUTH AND EAST THURSDAY TO SOUTH OF THE
PRIBILOFS BY FRIDAY AFTERNOON.  A WEAKENING LOW OVER THE COPPER RIVER
BASIN WILL MOVE TO THE YUKON TERRITORY WEDNESDAY.

.SHORT TERM FORECAST...
OUT EAST...COOLER AIR HAS MOVED IN FROM THE WEST.  SCATTERED SHOWERS
SHOULD DIMINISH THIS EVENING AND THEN BE CONFINED TO NEAR HIGHER
TERRAIN WEDNESDAY AS THE AIR MASS CONTINUES TO DRY OUT.  GUSTY SOUTH
WINDS THROUGHOUT COOK INLET AND SOUTH CENTRAL WILL DIMINISH THIS
EVENING AS THE SURFACE LOW OVER THE COPPER RIVER BASIN CONTINUES TO
WEAKEN AND MOVE TO THE YUKON. THE NEXT BIG STORM WILL BRING WIND AND
RAIN TO KODIAK ISLAND WEDNESDAY NIGHT AND THEN TO THE NORTH GULF
COAST THURSDAY.  EXPECT INCREASING CLOUDS OVER SOUTH CENTRAL THURSDAY
AND RAIN THURSDAY NIGHT AND FRIDAY.  THIS IS A WARM FORMER TROPICAL
SYSTEM SO SNOW LEVELS WILL BE HIGH..ABOVE 4000 FEET AND PRECIPITATION
MAY BE MODERATE TO HEAVY OVER SOUTHEAST UP SLOPE AREAS.

OUT WEST...A STRONG LOW WILL CONTINUE TO TRACK EAST SOUTH OF THE
ALEUTIAN ISLANDS. GALE FORCE TO STORM FORCE WINDS WILL ACCOMPANY THIS
LOW. AS THIS LOW MOVES SOUTH OF THE ALASKA PENINSULA THURSDAY A
SHORTWAVE WILL BEGIN TO MOVE SOUTH AND EAST FROM THE WESTERN BERING.
UPSLOPE SNOW SHOWERS IN WESTERLY FLOW ALONG THE ALASKA RANGE AND
INTERIOR SOUTHWEST ALASKA WILL TAPER OFF TONIGHT AS THE UPPER LOW
WEAKENS.

.LONG TERM FORECAST...
ASSUMING THE ALEUTIAN LOW TRACKS INTO THE COPPER RIVER BASIN BY
SATURDAY SOUTH CENTRAL SHOULD HAVE A BREAK IN PRECIPITATION SATURDAY.
THE TRACK OF THE NEXT LOW ON SUNDAY IS STILL A QUESTION.  IF IT
REMAINS OVER THE GULF IT WILL HAVE MINIMAL IMPACT ON SOUTH CENTRAL.
FOR NOW IT LOOKS LIKE CLOUDY WITH A CHANCE OF RAIN OR SHOWERS SUNDAY
WITH AN IMPROVING TREND EARLY NEXT WEEK FOR SOUTH CENTRAL.  OUT WEST
EXPECT A RIDGE OF HIGH PRESSURE TO MOVE ACROSS THE BERING AND
ALEUTIANS OVER THE WEEKEND WITH ANOTHER STORM MOVING TO THE WESTERN
ALEUTIANS BY LATE SATURDAY AND TO THE ALASKA PENINSULA ON MONDAY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 170 172 175 155 150 132
FIRE WEATHER...NONE

RHH SEP 09