Gale Warning 721, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
100 PM AKDT SUN OCT 3 2010

.ANALYSIS AND UPPER LEVELS...A CLOSED UPPER LOW IS CENTERED ALONG
THE KUSKOKWIM DELTA COAST THIS MORNING WITH A WEAK REFLECTION AT
THE SURFACE. THE MAIN STORM OF CONCERN THOUGH IS A LOW NEAR THE
SOUTHERN TIP OF THE KENAI PENINSULA. STORM FORCE WINDS ARE BEING
OBSERVED ALONG THE OCCLUDED FRONT...WHICH EXTENDS EASTWARD ALONG
THE NORTH GULF COAST. THE LOW IS TRACKING WEST-NORTHWEST AROUND
THE UPPER LOW TO THE WEST. THIS MOTION IS SLOWLY PUSHING THE FRONT
ONSHORE. THEREFORE...WINDS ARE ON THE WAY UP FROM PRINCE WILLIAM
SOUND TO TURNAGAIN ARM. RADAR IMAGERY SHOWS THE BULK OF PRECIP
WITH THIS SYSTEM IS GETTING HUNG UP ALONG THE COAST DUE TO
DOWNSLOPING ALONG THE KENAI AND CHUGACH MOUNTAINS.

.MODEL DISCUSSION...MODELS SHOW GOOD RUN-TO-RUN CONSISTENCY THROUGH
THE NEXT 3 DAYS AND ONLY MINOR ADJUSTMENTS WILL BE MADE TO EXISTING
FORECAST.

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...THE LOW ON THE GULF SIDE OF THE KENAI PENINSULA
WILL TRACK INTO COOK INLET LATER THIS AFTERNOON AND THEN INLAND TO
THE KUSKOKWIM VALLEY. THE OCCLUDED FRONT WILL RAPIDLY WEAKEN AS IT
CONTINUES TO PUSH ONSHORE. THIS WILL BRING AN END TO THE HEAVY RAIN
WHICH HAS BEEN FALLING ACROSS PRINCE WILLIAM SOUND THE LAST FEW DAYS.
THE FLOOD WARNING FOR RESURRECTION RIVER NEAR SEWARD AND THE SMALL
STREAM FLOOD ADVISORY FOR WESTERN PRINCE WILLIAM SOUND HAVE BOTH
BEEN CANCELLED. ONCE THE LOW IS IN THE INLET THE EAST-WEST GRADIENT
THROUGH TURNAGAIN ARM WILL RAPIDLY INCREASE. THEN AS THE LOW
CONTINUES TO TRACK NORTHWESTWARD STRONG PRESSURE RISES WILL MOVE
ACROSS THIS SAME AREA. THE COMBINATION OF THESE FACTORS WILL RESULT
IN A SURGE OF WINDS THROUGH TURNAGAIN ARM INTO ANCHORAGE AND THROUGH
THE KNIK RIVER VALLEY INTO PALMER AND WASILLA.  THERE MAY EVEN BE A
GUST OR TWO WHICH APPROACHES WARNING LEVELS ALONG TURNAGAIN ARM...BUT
IF SO IT WILL BE VERY BRIEF. WINDS WILL ALSO INCREASE FROM KAMISHAK
BAY TO KACHEMAK BAY AND UP THE INLET DUE TO PRESSURE RISES AND COLD
AIR ADVECTION. ALTHOUGH THE AREAS MENTIONED WILL SEE THE STRONGEST
WINDS...PRESSURE RISES ACROSS ALL OF SOUTHCENTRAL ALASKA WILL PRODUCE
A BRIEF PERIOD OF GUSTY WINDS...STRONGEST THROUGH CHANNELED AREAS.
THE PERIOD OF PEAK WINDS WILL GENERALLY FALL BETWEEN 4 PM AND 8 PM.

THERE AMY BE A BRIEF PERIOD OF RAIN ON THE LEE SIDE OF THE MOUNTAINS
AS THE LOW MOVES THROUGH...BUT THE BULK OF PRECIP WILL REMAIN ALONG
UPSLOPE AREAS ALONG THE COAST AND ALONG THE ALASKA RANGE. UPPER LEVEL
WAVES WILL CONTINUE TO PUSH ACROSS THE REGION THROUGH MONDAY NIGHT
WHICH WILL BRING A BRIEF SHOT OF RAIN TO INLAND AREAS WHILE STEADY
RAIN PERSISTS ALONG THE COAST.

MEANWHILE...A SHORT-WAVE SOUTH OF THE ALEUTIANS WILL DIG SOUTHWARD
AMPLIFYING THE UPPER TROUGH. ANOTHER MAJOR STORM WILL DEVELOP AHEAD
OF THIS TROUGH AND TRACK TO THE GULF OF ALASKA MONDAY NIGHT. EXPECT
GALE TO STORM FORCE WINDS OVER THE GULF WATERS. THIS LOW LOOKS LIKE
IT WILL TRACK INLAND NEAR CORDOVA WITH A SECONDARY LOW THEN FORMING
IN THE SOUND. UNDER THIS SCENARIO PRECIP WOULD INITIALLY BE CONFINED
TO PRINCE WILLIAM SOUND EASTWARD MONDAY NIGHT AND TUESDAY AND THEN
SPREAD TO AREAS FARTHER WEST ON WEDNESDAY. IN ANY CASE THE CONTINUED
TRACK OF LOWS FROM THE NORTHEAST PACIFIC MEANS THE AIRMASS OVER
SOUTHCENTRAL WILL REMAIN RELATIVELY WARM AND THE BULK OF PRECIP
WILL FALL AS RAIN.

SOUTHWEST ALASKA...THE REMNANTS OF THE GULF LOW WILL MOVE INTO THE
KUSKOKWIM VALLEY THIS EVENING AND THEN TRACK TO THE KUSKOKWIM DELTA
COAST BY EARLY MORNING. MEANWHILE...WEAK WAVES ROTATING AROUND THE
MAIN UPPER CENTER WILL CONTINUE TO PRODUCE ISOLATED TO SCATTERED
SHOWERS. THE COMBINATION OF THESE FEATURES WILL PRODUCE A CHANCE
OF PRECIP THROUGH MONDAY. CONDITIONS WILL THEN DRY OUT FOR TUESDAY
AS THE NEXT MAJOR SYSTEM MOVES INTO THE GULF.

BERING SEA/ALEUTIANS...WEAK UPPER WAVES DROPPING DOWN IN NORTHWEST
FLOW ALOFT WILL PRODUCE AREAS OF SHOWERS. OTHERWISE...CONDITIONS
WILL REMAIN VERY CALM ACROSS THE REGION.

.LONG TERM FORECAST...THE MEAN UPPER TROUGH POSITION WILL MOVE A
BIT EAST FROM ITS CURRENT LOCATION WHICH WILL PUSH THE PACIFIC
STORM TRACK FURTHER EAST TOWARD SOUTHEAST ALASKA. EVEN WITH
THIS...THE STORMS COULD STILL TRACK BACK TOWARD SOUTHCENTRAL.
NORTHWEST FLOW ALOFT WILL PERSIST ACROSS THE BERING SEA WITH
GENERALLY WEAK FEATURES AFFECTING THE REGION.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE WARNING...120 165 170 172.
FIRE WEATHER...NONE.

SEB OCT 10