High Wind in Alaska, November 19, 2009

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM AKST WED NOV 18 2009

.MODEL DISCUSSION...ALL MAJOR MODELS ARE IN GOOD SYNOPTIC AGREEMENT
THIS MORNING THROUGH 84 HOURS...WITH THE LARGEST AND MOST PROMINENT
FEATURE BEING THE STRONG LOW ENTERING THE WESTERN BERING. MODEL
DISAGREEMENT THEN ARISES SURROUNDING THE FATE OF THE LARGE BERING LOW
AS IT ENTERS THE EASTERN BERING ON SATURDAY AFTERNOON AND BEGINS TO
BREAK APART. AT THIS TIME THE GFS IS PREFERRED...MOSTLY DUE TO BETTER
CONSISTENCY OVER THE LAST FEW RUNS VERSUS THE ECMWF. REGARDLESS...ALL
MODELS DO SLOWLY SLIDE THE ACTIVE WEATHER EAST INTO THE GULF FOR THE
START OF NEXT WEEK. FOR THE IMMEDIATE SHORT TERM FORECAST...THE ONLY
MODEL DISAGREEMENT FOCUSES ON THE GULF...WHERE THE SUPER RESOLUTION
OF THE NAM SEEMS TO BE BEST HANDLING THE SMALL CIRCULATIONS IN THE
GULF AT THIS TIME.

.ANALYSIS AND UPPER LEVELS...
A STRONG SHORTWAVE TROUGH IS APPROACHING THE WESTERN ALEUTIANS. THIS
IS AMPLIFYING A TRANSIENT RIDGE OVER THE CENTRAL BERING SEA...WHICH
IS PUSHING ON THE LONGWAVE TROUGH SITUATION OVER THE GULF OF ALASKA.
A 135 KT JET RIDING UP THE BERING RIDGE IS SUPPORTING STRONG SURFACE
CYCLOGENESIS WEST OF SHEMYA. MEANWHILE...A 175 KT JET COMING DOWN THE
FRONT OF THE BERING RIDGE IS ENHANCING STRONG NORTHWESTERLY WINDS
OVER THE EASTERN ALEUTIANS AND PARTS OF SOUTHWEST ALASKA. A SERIES OF
WEAK LOWS IN THE NORTHERN GULF ARE PRODUCING PERIODS OF TIGHTENED
PRESSURE GRADIENTS AT THE USUAL OUTFLOW AREAS....THOMPSON
PASS...BROAD PASS...COPPER RIVER DELTA...ALONG WITH NUMEROUS SNOW
SHOWERS FROM CORDOVA TO PRINCE WILLIAM SOUND AND THE EASTERN KENAI
PENINSULA.

.SHORT TERM FORECAST...
.EAST OF THE ALASKA RANGE...THE SURFACE LOW IN THE GULF IS A BIT
FURTHER NORTH THAN PREVIOUSLY FORECAST...WHICH IS BRINGING MORE
PRECIPITATION INTO THE AREA THAN EXPECTED. CANNOT RULE OUT A SHOWER
OR TWO MAKING IT OVER THE CHUGACH INTO THE ANCHORAGE AREA TONIGHT.
MAIN QUESTION WILL BE WHETHER OR NOT CLOUD COVER WILL KEEP THE FLOOR
FROM DROPPING OUT ON OVERNIGHT TEMPS. COLD NORTHERLY WINDS WILL
CONTINUE FOR ONE MORE NIGHT IN THE UPPER SUSITNA VALLEY AND THOMPSON
PASS...BEFORE BEGINNING TO DIMINISH BY MIDDAY THURSDAY. THUS WILL
CONTINUE WIND CHILL ADVISORIES FOR ONE MORE NIGHT.

.WEST OF THE ALASKA RANGE...STRONG NORTHWESTERLIES OVER THE MAINLAND
AND EASTERN ALEUTIANS SHOULD COME DOWN OVERNIGHT AS SURFACE HIGH
PRESSURE MOVES INTO THE AREA AND THE STRONGEST GRADIENT MOVES OFF TO
THE EAST. OTHERWISE...CLEAR SKIES AND ANOTHER COLD NIGHT ON TAP. OVER
THE WESTERN ALEUTIANS...GALE FORCE SOUTHEASTERLY WINDS WILL INCREASE
TO HURRICANE FORCE SOUTHWESTERLY WINDS BY MORNING AS RAPIDLY
INTENSIFYING LOW PASSES TO THE NORTH OF SHEMYA. EXPECT VERY WINDY
CONDITIONS TO PERSIST FOR NEXT FEW DAYS AS LOW MAKES ONLY SLOW
PROGRESS EASTWARD. STORM FORCE SOUTHEASTERLY WINDS WITH THE
ASSOCIATED WEATHER FRONT ARE EXPECTED TO MAKE IT AS FAR EAST AS THE
CENTRAL ALEUTIANS AND POSSIBLY PRIBILOFS BY THURSDAY AFTERNOON. AMPLE
WARM AIR WITH THIS SYSTEM WILL EASILY CONVERT ALL PRECIPITATION TO
RAIN AS IT PROGRESSES.

.LONG TERM FORECAST...NO CHANGE TO THE EXTENDED FORECAST AT THIS
TIME...STILL APPEARS THE COLD AND RELATIVELY DRY WEATHER OVER
SOUTHCENTRAL AND THE GULF WILL COME TO AN END AS ACTIVE WEATHER FROM
THE BERING SLIDES EASTWARD FOR THE START OF NEXT WEEK. THIS WILL ALSO
USHER IN A RETURN TO MUCH MORE SEASONAL TEMPERATURES.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WARNING 191
MARINE...HURRICANE FORCE WIND WARNING 176
         STORM 172 175 185
         GALE 130 132 150 155 160 165 170 179 180
         HEAVY FREEZING SPRAY 121 130 138 140 150 160 180
FIRE WEATHER...NONE.

AMD NOV 09