Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 280053
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
353 PM AKST TUE JAN 27 2015

.ANALYSIS AND UPPER LEVELS...
UPPER AIR...
A RIDGE AXIS EXTENDS FROM OVER THE EASTERN GULF TO OVER BRISTOL
BAY. WEAK WESTERLY FLOW IS EVIDENT ACROSS THE SOUTHERN AND CENTRAL
MAINLAND. WATER VAPOR IMAGERY SHOWS MOISTURE ASSOCIATED WITH A
WEAKENING FRONTAL BOUNDARY BEING ENTRAINED IN THE WESTERLY FLOW
AND SPREADING EAST ACROSS THE SOUTHERN MAINLAND. TWO PROMINENT
UPPER LOW CENTERS ARE EVIDENT ON THE SATELLITE IMAGE...A FAIRLY
VIGOROUS CENTER ASSOCIATED WITH A DEVELOPING SURFACE LOW
SKIRTING THE AK PEN FROM THE SOUTH AND AN OLDER CENTER DRIFTING
SOUTH OF THE EAST CENTRAL ALEUTIANS.

SURFACE...
EAST...FAIR SKIES AND COLD TEMPERATURES CONTINUED ACROSS THE
COPPER RIVER BASIN. TEMPERATURES MODERATED SOME WEST OF THE
CHUGACH/TALKEETNA MOUNTAINS OVERNIGHT AS CLOUDS AND SOME LIGHT
SNOW ASSOCIATED WITH WEAK OVERRUNNING SPREAD ACROSS THE AREA.
GENERALLY FAIR SKIES WERE EVIDENT ACROSS THE GULF. GUSTY OUTFLOW
WINDS ASSOCIATED WITH STRONG THERMAL AND PRESSURE GRADIENTS WERE
EVIDENT ACROSS NE PRINCE WILLIAM SOUND. GALE FORCE NORTHERLY
WINDS WERE OBSERVED OVER VALDEZ NARROWS ALONG WITH STRONG WINDS
AND LOW WIND CHILLS FROM KEYSTONE CANYON TO THOMPSON PASS.

WEST...MODERATE SNOW AND AREAS OF BLOWING SNOW ACROSS BRISTOL BAY
HAVE TRANSITIONED INTO SCATTERED SNOW SHOWERS. A LITTLE LIGHT
SNOW ASSOCIATED WITH A WEAKENING FRONTAL BAND IS MOVING WEST
TOWARD THE KUSKOKWIM DELTA. A FRONTAL BAND ADVANCING FROM THE
SOUTH TOWARD THE AK PEN IS PRODUCING GUSTY WINDS ALONG THE AK PEN
AND ASSOCIATED COASTAL MARINE AREAS. FURTHER WEST...HIGH PRESSURE
WAS EVIDENT OVER THE WESTERN BERING SEA. THE PINCH IN PRESSURE
BETWEEN THIS FEATURE AND GENERALLY LOWER PRESSURE TO THE EAST
PRODUCED BRISK NORTHERLY WINDS ACROSS THE CENTRAL AND EASTERN
ALEUTIANS. COLD AIR SPILLING DOWN THE FORWARD SIDE OF THE RIDGE
ACROSS THE BERING SEA AND CENTRAL ALEUTIANS WAS EVIDENT BY THE
PRESENCE OF EXTENSIVE OPEN CELL CU OBSERVED ON SATELLITE IMAGERY.

&&

.MODEL DISCUSSION...
THE 12Z MODELS WERE IN FAIRLY GOOD AGREEMENT THROUGH THE SHORT
TERM. THE GFS MODEL IN GENERAL WILL BE USED OUT WEST WITH A COMBO
OF THE NAM AND CANADIAN IN THE EAST.

&&

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

MOSTLY CLOUDY SKIES INLAND FOR MUCH OF SOUTHCENTRAL WILL GRADUALLY
DECREASE AND BECOME PARTLY CLOUDY TO MOSTLY CLEAR THROUGH
WEDNESDAY...EXCEPT TOWARD THE NORTH GULF COAST WHERE MID TO HIGH
LEVEL CLOUDS WILL CONTINUE TO INCREASE AS A WEATHER FRONT PIVOTS
NORTH AND NORTHWEST TOWARD THE NORTH GULF COAST. TEMPERATURES
TONIGHT FOR MOST AREAS WILL BE WARMER THAN SUNDAY NIGHT BUT
COOLER THAN OBSERVED LAST NIGHT...WITH A NOTABLE EXCEPTION BEING
THE COPPER RIVER BASIN WHERE TEMPERATURES WILL AGAIN PLUMMET INTO
THE -30S.

TOWARD KODIAK...THE AFOREMENTIONED FRONT WILL STALL NEAR OR OVER
THE AREA BY THURSDAY...WITH MAINLY RAIN CONTINUING IN THE CITY OF
KODIAK BUT MIXING OR CHANGING TO SNOW AT HIGHER ELEVATIONS OF THE
ISLAND WITH INCREASED ONSHORE NORTHEASTERLY WINDS.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
THE KUSKOKWIM VALLEY AND DELTA WILL REMAIN COLD FOR THE NEXT FEW
DAYS WHILE AREAS AROUND BRISTOL BAY WILL BE WARMER AND WINDIER.
EXCEPT FOR SOME SNOW SHOWERS OVER THE ALASKA AND ALEUTIAN RANGES
AND FEW LINGERING SHOWERS OVER THE DELTA...THE AREA WILL BE DRY
THROUGH FRIDAY.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
A TIGHT PRESSURE GRADIENT WILL PERSIST BETWEEN HIGH PRESSURE
BUILDING INTO THE WESTERN BERING AND LOW PRESSURE CIRCULATING
SOUTH OF THE AKPEN. THIS WILL KEEP STORM FORCE WINDS ACROSS THE
CENTRAL ALEUTIANS THROUGH WEDNESDAY AND GALES OVER REST OF THE
ALEUTIANS AND PRIBILOFS DURING THE SAME PERIOD. RAIN AND SNOW
SHOWERS WILL PERSIST ALONG THE EASTERN HALF OF THE CHAIN THROUGH
WEDNESDAY NIGHT. THE REMAINDER OF THE WORK WEEK WILL BE GENERALLY
DRY.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
SNOW SHOWERS WILL LINGER ALONG THE GULF COAST INTO FRIDAY NIGHT AS
A FRONT GRADUALLY WEAKENS OVER THE NORTHERN GULF. AFTER THAT...
MODELS HAVE COME INTO SLIGHTLY BETTER AGREEMENT IN THE PAST 24
HOURS WITH PLACEMENT OF THE UPPER HIGH THAT WILL MIGRATE EASTWARD
FROM THE BERING SEA TO THE MAINLAND THIS WEEKEND. THIS WILL HELP
TO KEEP A BROAD NORTH PACIFIC LOW WELL SOUTH OF THE REGION THROUGH
EARLY NEXT WEEK AS IT REMAINS IN THE VICINITY OF 50 DEGREES NORTH
LATITUDE. THE PRECIPITATION ASSOCIATED WITH THIS FEATURE IS THUS
EXPECTED TO REMAIN SOUTH OF THE AREA WITH THE BULK OF THE IMPACTS
LIMITED TO THE SOUTHERN GULF AND KODIAK ISLAND AS WELL AS THE
ALASKA PENINSULA. THIS WILL KEEP THE SOUTHERN MAINLAND IN A DRY
OFFSHORE FLOW PATTERN AS TEMPERATURES GRADUALLY MODERATE TO NEAR
NORMAL VALUES...WITH A FAVORABLE PRESSURE GRADIENT SUPPORTING
GUSTY WINDS ALONG THE NORTHERN GULF COAST.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...STORM WARNING 173 175 176 177.
GALE WARNING 120 127 130 131 132 138 150 155 165 170 171 172 174
             179 180.
HEAVY FREEZING SPRAY WARNING...126 127 128 139 140 141 160 180 185.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...BC
SOUTHCENTRAL ALASKA...CC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DS
LONG TERM...CB


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