Small Craft Advisory 779, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE ANCHORAGE AK
431 PM AKDT MON OCT 5 2015

CORRECTED

.ANALYSIS AND UPPER LEVELS...
THE UPPER LEVEL PATTERN IS BEGINNING TO CHANGE FROM THE ZONAL FLOW
WE SAW YESTERDAY INTO A MORE AMPLIFIED PATTERN. THE WEAK RIDGE
OVER SOUTHCENTRAL ALASKA IS BUILDING AND MOVING EASTWARD AS THE
UPPER LEVEL TROUGH OVER THE NORTHERN BERING SEA WILL DIG
SOUTHEASTWARD AND BECOME THE MAIN UPPER LEVEL LOW BY WEDNESDAY.
THE JET STREAM IS CURRENTLY RUNNING JUST SOUTH OF THE ALEUTIANS
FROM DUE WEST TO EAST AT AROUND 125 TO 135 KT BUT IT WILL
STRENGTHEN AS THE UPPER LEVEL LOW DEVELOPS AND TURNS MORE TO THE
NORTHWEST TO SOUTHEAST.
GALE FORCE WINDS HAVE BEEN OCCURRING NEAR THE SURFACE LOW AND
FRONT IN THE EASTERN BERING SEA. THE LOW WILL NOT MOVE MUCH
FARTHER TO THE EAST BUT WILL MAINTAIN STRENGTH FOR THE NEXT DAY AS
IT DRIFTS TO THE NORTHWEST. THIS IS LARGELY DUE TO THE BUILDING
RIDGE OVER THE EASTERN PART OF THE STATE. THIS RIDGE HAS TRAPPED
LARGE AMOUNTS OF MOISTURE UNDERNEATH IT PRODUCING WIDESPREAD
STRATUS AND FOG FROM KODIAK NORTHWARD THROUGH COOK INLET AND THE
ENTIRE SUSITNA VALLEY.

&&

.MODEL DISCUSSION...
MODELS ARE IN GOOD AGREEMENT WITH THE SYNOPTIC PATTERN ONCE AGAIN.
THE BIGGEST ITEM TO NOTE IS THEY AS A COLLECTIVE THEY ARE SLOWLY
INCREASING THE STRENGTH OF THE LOW MOVING INTO THE GULF LATER IN
THE WEEK. WHILE THE TIMING OF THE LOW REMAIN LARGELY UNCHANGED
STRONGER WINDS WILL LIKELY BEGIN TO IMPACT THE GULF AND GULF COAST
FASTER THAN IT LOOKED EARLIER. THIS IS REFLECTED IN THE LATEST
FORECASTS.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...

THE SHORT TERM FORECAST THROUGH WEDNESDAY WILL BE THE ONSET OF A
WET AND WINDY PATTERN ALONG THE GULF AND SURROUNDING COAST...WITH
A PERSISTENT PATTERN INLAND OF CLOUDS AND FOG IMPROVING DURING THE
AFTERNOONS. THIS EVENING A FRONT MOVES INTO THE SOUTHERN GULF AND
THEN HEADS SLOWLY NORTH THROUGH TUESDAY. THIS SYSTEM SPREADS RAIN
FROM THE SOUTHERN GULF INTO THE KENAI AND NORTHERN GULF BY TUESDAY
AFTERNOON. GUSTY WINDS ARE EXPECTED ALONG THE FRONTAL BOUNDARY
WITH SMALL CRAFT TO GALE STRENGTH WINDS NEAR THE BARREN ISLANDS.
WINDS ARE STILL EXPECTED TO INCREASE ACROSS THE TURNAGAIN ARM AND
PORTAGE VALLEY EARLY TUESDAY MORNING AND THEN CONTINUE THROUGH
WEDNESDAY WITH THE PRESSURE GRADIENT REINFORCED BY THE NEXT FRONT
MOVING FROM THE NORTH PACIFIC. THIS NEXT FRONT WILL ADDITIONALLY
BRING GUSTIER WINDS ACROSS THE COOK INLET...NORTHERN AND WESTERN
GULF. FOG CONDITIONS ARE EXPECTED TO DEVELOP AGAIN TONIGHT WITH
ADEQUATE SURFACE MOISTURE AND CALM WINDS.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
THE FRONT ASSOCIATED WITH THE BERING SEA LOW WILL MOVE INTO THE
SOUTHWESTERN MAINLAND TONIGHT...BECOMING STATIONARY ON TUESDAY
AND BEGINNING TO DISSIPATE TUESDAY NIGHT. WIDESPREAD RAINFALL IS
EXPECTED OVER THE REGION AS THERE IS A STRONG SOUTHERLY FLOW WITH
THIS FRONT...ADVECTING DECENT AMOUNT OF NORTH PACIFIC MOISTURE
ALONG THE BOUNDARY. THE HEAVIEST RAINFALL AMOUNTS ARE EXPECTED
OVER THE BRISTOL BAY REGION OVERNIGHT TONIGHT...MAINLY ALONG THE
AHKLUN MOUNTAINS. AS THE FRONT STALLS OUT TUESDAY EVENING...STEADY
RAIN WILL TRANSITION A MORE SHOWERY REGIME.

WINDS ALONG THE SOUTHWESTERN COAST WILL REMAIN STRONG THROUGH THIS
EVENING AS THE FRONT MOVES INLAND. EXPECT GALE FORCE WINDS TO
DIMINISH OVER THE AREA AFTER MIDNIGHT TONIGHT.

WITH ONSHORE FLOW EXPECTED OVER MUCH OF THE COAST...PATCHY FOG IS
EXPECTED TO PERSIST THROUGH THE PERIOD.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
WINDS WILL REMAIN NEAR OR AT GALE FORCE THROUGH TUESDAY EVENING
OVER MUCH OF THE REGION AS THE LOW MOVES NORTHWARD TO NEAR
GAMBELL ISLAND. AS THE LOW BEGINS TO MOVE SOUTHWESTWARD ON TUESDAY
NIGHT...WINDS EAST OF 180 WILL GENERALLY TURN SOUTHWESTERLY AND
DECREASE TO BELOW SMALL CRAFT LEVELS. WEST OF 180...WINDS TUESDAY
NIGHT WILL INCREASE TO NEAR-GALE OR GALE FORCE OVER THE WESTERN
BERING SEA AS A SHORTWAVE DIVES SOUTHEASTWARD ALONG THE WESTERN
PERIPHERY OF THE UPPER LEVEL LOW.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
THE MODELS CONTINUE TO TRACK THE RAPIDLY DEEPENING NORTH PACIFIC
LOW JUST SOUTH OF THE LOWER WESTERN GULF BY WEDNESDAY. BY LATE
WEDNESDAY EVENING AS THE LOW TRACKS CLOSER TO THE CHIRIKOF ISLAND
REGION THE PRESSURE GRADIENTS WILL STRENGTHEN RESULTING IN STRONG
NORTHEASTERLY GALE FORCE WINDS TO THE NORTHERN GULF EXTENDING
THROUGH THE BARREN ISLANDS...SHELIKOF STRAIT AND THE SOUTHERN COOK
INLET THROUGH THURSDAY MIDDAY. THE ASSOCIATED WEATHER FRONT WILL
BE MOVING THROUGH THE AFOREMENTIONED REGION BRINGING WIDESPREAD
RAIN AND STRATUS. THE ECMWF MODEL SEEMS TO BE THE OUTLIER WITH
THIS SYSTEM AS IT TRIES TO PUSH THIS SYSTEM FARTHER EAST THAN THE
OTHER MODELS BY THURSDAY AFTERNOON. THIS IS HIGHLY UNLIKELY DUE TO
AN UPPER LEVEL NEGATIVE TILTED RIDGE WILL BE POSITIONED ALONG THE
NORTHERN GULF REGION AS WE HEAD INTO THE WEEKEND. THE MODELS ARE
DEPICTING THIS SYSTEM BECOMING STATIONARY JUST SOUTH OF THE
EASTERN ALEUTIANS BY FRIDAY. THIS SYSTEM WILL THEN PHASE IN WITH A
ANOTHER NORTH PACIFIC LOW THAT IS TRACKING NORTHWARD INTO A BROAD
AREA OF LOW PRESSURE OVER THE CENTRAL GULF BY SATURDAY. THE
CONFIDENCE IS LOW WITH TOO MUCH UNCERTAINTY WITH THE PHASING IN
OF THESE TWO SYSTEMS DUE TO THE TIMING AND STRENGTH AS WE HEAD
INTO THE WEEKEND.

WHILE...ON THE BERING SIDE THERE IS A DECAYING LOW THAT WILL TRACK
FROM THE NORTHERN TO CENTRAL BERING BY THURSDAY MORNING BEFORE
DISSIPATING BY THURSDAY AFTERNOON. THIS WILL CONTINUE TO BRING A
SHOWERY WEATHER REGIME WITH THE WINDS SHIFTING TO A MORE
NORTHERLY FLOW BY FRIDAY. THE NEXT SYNOPTIC FEATURE TO AFFECT THE
BERING WILL BE A NORTH PACIFIC LOW TRACKING CLOSER TO THE EASTERN
ALEUTIANS FROM THE PACIFIC SIDE HEADING INTO THE WEEKEND. THIS
WILL BRING ABUNDANT MOISTURE SPILLING OVER THE ALASKA PENINSULA
INTO THE EASTERN ALEUTIANS AND THE SOUTHWEST ALASKA REGION AS THIS
SYSTEM BECOMES ALMOST STATIONARY NEAR CHIRIKOF ISLANDS BY FRIDAY.
THIS SYNOPTIC FEATURE WILL KEEP THE BERING AND THE ALUETIAN CHAIN
IN NORTHERLY FLOW SCATTERED SHOWERY WEATHER REGIME THROUGH THE
WEEKEND.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALES 131 180 181 185.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...EZ
SOUTHCENTRAL ALASKA...KH
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...RF
LONG TERM...PD