Gale Warning 150, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM AKST TUE FEB 16 2010

.MODEL DISCUSSION...SYNOPTIC SCALE INITIALIZATIONS REASONABLE. MODEL
MSLP FORECAST SOLUTIONS ARE IN SOMEWHAT AGREEMENT THROUGH ABOUT 36-48
HRS. SOLUTIONS TEND TO DIVERGE BEYOND THAT...ESPECIALLY OVER THE
BERING SEA AND ALEUTIANS. ALTHOUGH MODELS DISAGREE ON POSITIONING OF
LOW CENTERS SOUTH OF THE AK PEN AND NE PACIFIC...ALL ARE IN GENERAL
AGREEMENT ON THE DEEP SOUTHERLY FLOW SETTING UP OVER THE GULF LATE
WED THROUGH THU. DUE TO MODEL UNCERTAINTY...AFTERNOON PACKAGES WILL
BE A BLEND OF THE NAM AND OFFICIAL GRIDS THROUGH ABOUT 60 HRS WITH
LITTLE CHANGE BEYOND.

.ANALYSIS AND UPPER LEVELS...
.500MB...SHORT WAVE OVER THE NORTH GULF MOVES INTO THE INTERIOR
TONIGHT. THE WEST COAST/SOUTHEAST ALASKA RIDGE THEN BUILDS NORTH
THROUGH THU. THIS COMBINED WITH BROAD TROUGH WEST OF 145W OVER THE NE
PACIFIC SETS UP DEEP SOUTHERLY FLOW OVER THE GULF AND SOUTHCENTRAL
ALASKA WED. THE SOUTHERLY FLOW OVER THE GULF IS PERTURBED SOME THU AS
A SHORT WAVE PUSHES NORTH WEST OF 145W.

STRONG LOW WEST OF THE ALEUTIANS INTENSIFIES AS IT MOVES TO THE
WESTERN ALEUTIANS WED MORNING. THE CENTER THEN WEAKENS AS IT MOVES
JUST EAST OF SHEMYA THU AFTERNOON. THE TROUGH ASSOCIATED WITH THE LOW
ELONGATES EAST WITH POSSIBLE SECONDARY DEVELOPMENT NEAR THE EASTERN
ALEUTIANS THU AFTERNOON.

...SURFACE...
.SOUTHCENTRAL/GULF OF ALASKA...
WEAKENING LOW OVER THE GULF OF ALASKA MOVES TO NEAR KODIAK TONIGHT
AND THEN INTO EASTERN BRISTOL BAY EARLY WED AND SHOULD DISSIPATE.
GALES ALONG THE NORTHERN GULF WILL DIMINISH TONIGHT BUT SHOULD
INCREASE AGAIN WED AS NEXT OCCLUDED FRONT MOVES NORTH. GAP WINDS
ACROSS THE ANCHORAGE BOWL (TURNAGAIN ARM) AND WINDS HIGHER
ELEVATIONS) SHOULD INCREASE THIS EVENING WITH A REVERSAL OF THE
PRESSURE GRADIENTS. PRECIPITATION WILL ALSO INCREASE ALONG THE GULF
AS THE MID LEVEL FLOW SHIFTS TO THE SOUTHEAST.

A LONG SOUTHERLY FETCH OF MOISTURE EXTENDING FROM THE NORTHEAST
PACIFIC TO OVER THE NORTH GULF COAST INCLUDING PRINCE WILLIAM SOUND
AND THE EASTERN KENAI PENINSULA DEVELOPS LATE IN THE DAY WEDNESDAY.
SOUTHERLY FLOW WILL BRING WARMER AIR AND LOCALLY HEAVY RAINS TO LOWER
ELEVATIONS ESPECIALLY NEAR CORDOVA AND THE EASTERN KENAI PENINSULA.
THESE CONDITIONS MAY CAUSE SOME MINOR FLOODING OF SMALL STREAMS AND
PONDING DUE TO DRAINAGE ISSUES IN URBAN AREAS BEGINNING LATE
WEDNESDAY NIGHT AND CONTINUING INTO EARLY FRIDAY.
ADDITIONALLY...RISING FREEZING LEVELS COMBINED WITH LOCALLY HEAVY
SNOWS AT HIGHER ELEVATIONS COULD INCREASE AVALANCHE RISK IN THE
EASTERN KENAI MOUNTAINS.

.SOUTHWEST...
WEAK TROUGH WILL PERSIST OVER SOUTWEST ALASKA THROUGH WED NIGHT WITH
GENERALLY MIXED RAIN AND SNOW IN THE BRISTOL BAY REGION AND SCATTERED
SNOW OVER THE DELTA (LITTLE ACCUMULATION). WINDS WILL ALSO BE
GENERALLY LIGHT. PRECIPITATION AND INCREASED WINDS ARE POSSIBLE AS AN
ORGAINZED WAVE WITH ASSOCIATED FRONTAL TROUGH MOVES IN FROM THE SOUTH
THU NIGHT AND FRI.

ALEUTIANS...STORM FORCE LOW INTENSIFIES AS IT APPROACHES THE
ALEUTIANS TONIGHT THEN SLOWLY WEAKENS AS IT MOVES EAST OF SHEMYA THU.
WARNING LEVEL WINDS AND STORM FORCE WINDS ARE EXPECTED AHEAD OF THE
ASSOCIATED FRONTAL SYSTEM OVER THE WESTERN ALEUTIANS TONIGHT. WINDS
OVER THE AREA SHOULD DIMINISH SOME EARLY WED MORNING. ASSOCIATED
FRONTAL TROUGH ELONGATES SE AS TRIPLE POINT DEVELOPS NEAR THE EASTERN
ALEUTIANS THU. SOME BLOWING SNOW CONDITIONS CAN BE EXPECTED AHEAD OF
THE FRONT AS IT TRACKS ACROSS THE ALEUTIANS...HOWEVER TEMPS SHOULD
WARM QUICKLY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WARNING ZONE 191
MARINE...STORM 175 176. GALE 120 125 130 140 170 172.
         HEAVY FREEZING 195.
FIRE WEATHER...NONE.

RMC FEB 10

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE ANCHORAGE AK
11 AM AKST TUE FEB 16 2010

AKZ125-131-135-180100-

A LONG SOUTHERLY FETCH OF MOISTURE EXTENDING FROM THE NORTHEAST
PACIFIC TO OVER THE NORTH GULF COAST INCLUDING PRINCE WILLIAM SOUND
AND THE EASTERN KENAI PENINSULA DEVELOPS LATE IN THE DAY WEDNESDAY.
SOUTHERLY FLOW WILL BRING WARMER AIR AND LOCALLY HEAVY RAINS TO LOWER
ELEVATIONS ESPECIALLY NEAR CORDOVA AND THE EASTERN KENAI PENINSULA.
THESE CONDITIONS MAY CAUSE SOME MINOR FLOODING OF SMALL STREAMS AND
PONDING DUE TO DRAINAGE ISSUES IN URBAN AREAS BEGINNING LATE
WEDNESDAY NIGHT AND CONTINUING INTO EARLY FRIDAY.
ADDITIONALLY...RISING FREEZING LEVELS COMBINED WITH LOCALLY HEAVY
SNOWS IN AT HIGHER ELEVATIONS COULD INCREASE AVALANCHE RISK IN THE
EASTERN KENAI MOUNTAINS.

THE WEATHER SERVICE WILL CONTINUE TO MONITOR THE SITUATION AS
CONDITIONS DEVELOP.

RMC FEB 10