Small Craft Advisory 175, NWS Fairbanks, AK

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
145 PM AKDT THU OCT 8 2015

.DISCUSSION...
ALOFT...PERSISTENT LOW REMAINS IN THE GULF OF ALASKA AROUND 230
MILES SSE OF KODIAK...WITH A DOWNSTREAM RIDGE THAT EXTENDS FROM
THE EASTERN INTERIOR OF ALASKA SOUTHEASTWARD THROUGH BRITISH
COLOMBIA AND INTO THE PACIFIC NORTHWEST. A 527 DM LOW WAS SEEN
EARLY THIS MORNING OVER THE CENTRAL BEARING SEA. NORTH OF THIS
FEATURE...A RIDGE OF HIGH PRESSURE EXTENDS OVER THE CHUKCHI AND
WESTERN BEAUFORT SEA. FINALLY...500 DM LOW WAS SEEN OVER FAR
NORTHERN CANADA AT 71 N 97 W WITH SHORT WAVE TROUGHING EXTENDING
EAST OF THE LOW AND DROPPING SOUTHWARD FROM THE HIGH ARCTIC.

SURFACE...968 MB LOW REMAINS VERTICALLY STACKED BELOW GULF OF
ALASKA LOW...WITH A TROUGH OF LOW PRESSURE EXTENDING TO THE
NORTHWEST INTO THE CENTRAL BERING SEA. BROAD HIGH PRESSURE AT 1030
MB EXTENDS OVER THE CHUKCHI AND BEAUFORT SEAS.

MODEL GUIDANCE...MODELS IN GOOD AGREEMENT OF OVERALL OMEGA
BLOCKING PATTERN PERSISTING OVER ALASKA THROUGH THIS
WEEKEND...WITH BROAD LOW PRESSURE ALOFT IN THE GULF AND ANOTHER
AREA OF LOW PRESSURE OVER THE CANADIAN ARCHIPELAGO. IN BETWEEN
RIDGING WILL REMAIN FROM THE NORTH SLOPE...EXTENDING SOUTHWARD
THROUGH EASTERN INTERIOR OF ALASKA AND INTO THE PACIFIC
NORTHWEST. A SERIES OF SHORTWAVE TROUGHS WILL WEAKEN THE RIDGE
FRIDAY AND SATURDAY...WITH THE RIDGE EXPECTED TO BECOME
REESTABLISHED ON SUNDAY. OMEGA BLOCK WILL BEGIN TO BREAK DOWN
LATER SUNDAY WITH GULF OF ALASKA LOW GRADUALLY WEAKENING AND
SHIFTING EASTWARD. BROAD SCALE TROUGHING WILL DEVELOP OVER THE
BERING SEA THIS WEEKEND. AT THE SURFACE...LOW PRESSURE WILL REMAIN
IN THE GULF THROUGH THE WEEKEND. THE REMNANTS OF TROPICAL CYCLONE
OHO WILL MOVE INTO THE EASTERN GULF OF ALASKA AND WILL PASS NEAR
YAKUTAT BY LATE FRIDAY EVENING...MERGING WITH THE EXISTING LOW IN
THE GULF AND WEAKENING SATURDAY. HIGH PRESSURE RIDGE OVER THE
CHUKCHI AND BEAUFORT SEAS WILL GRADUALLY WEAKEN THROUGH FRIDAY AS
997 MB LOW IN THE HIGH ARCTIC SLIDES TO THE SOUTH AND STRENGTHENS
TO A 995 MB LOW IN THE EAST SIBERIAN SEA BY LATE SUNDAY NIGHT.

NORTH SLOPE...NO MAJOR IMPACTS ARE EXPECTED HERE THROUGH THE SHORT
AND MEDIUM RANGE. GUSTY WINDS ARE EXPECTED OVER THE ARCTIC COAST
THROUGH THE WEEKEND DUE TO PRESSURE GRADIENT THAT EXISTS OVER THE
NORTHERN TWO THIRDS OF MAINLAND ALASKA. GALE CONDITIONS WILL EXIST
OFF THE NORTHWEST ARCTIC COAST THROUGH FRIDAY. ONSHORE FLOW WILL
GENERATE PERIODS OF SEA INDUCED FLURRIES OR FREEZING DRIZZLE
THROUGH FRIDAY AND POSSIBLY INTO SATURDAY.

WEST COAST...BROAD LOW PRESSURE IN THE GULF OF ALASKA WILL BRING
SCATTERED RAIN OR SNOW SHOWERS MAINLY TO THE SOUTHWEST ALASKA
THROUGH SATURDAY. THIS AREA WILL EXPAND TO MORE OF THE WEST COAST
BY SUNDAY AS BROADER TROUGHING EXPANDS INTO THE BERING SEA. THE
STRONG PRESSURE GRADIENT BETWEEN HIGH PRESSURE IN THE ARCTIC AND
LOW PRESSURE IN THE GULF WILL KEEP GUSTY WINDS OVER THE WEST COAST
THROUGH TONIGHT...GRADUALLY DIMINISHING ON FRIDAY.

INTERIOR...GUSTY WINDS WILL CONTINUE UNDER THE NORTHEASTERLY FLOW
REGIME THROUGH AT LEAST TONIGHT...MAINLY FOCUSED IN THE MIDDLE
TANANA VALLEY NEAR DELTA AND OVER SUMMITS OF THE EASTERN AND
CENTRAL INTERIOR. A COUPLE WEAK SHORT WAVES WILL ROUND THE
BROADER PARENT LOW OVER THE GULF IN THE NEXT COUPLE DAYS. THE
FIRST WILL MOVE INTO THE SOUTHEAST INTERIOR TONIGHT...BRINGING
SCATTERED RAIN AND SNOW SHOWERS ALONG AND SOUTH OF THE YUKON RIVER
TONIGHT INTO FRIDAY. ANY SNOW ACCUMULATION IS EXPECTED TO BE
AROUND AN INCH OR LESS. A SECOND WAVE...WHICH IS ACTUALLY THE
REMNANTS OF POST-TROPICAL CYCLONE OHO...WILL BRING MORE RAIN AND
SNOW SHOWERS TO THE SOUTHEAST INTERIOR FOR SATURDAY. AGAIN ANOTHER
INCH OR TWO OF SNOW ACCUMULATION LOOKS TO OCCUR WITH THIS SECOND
WAVE. HIGH PRESSURE WILL BUILD INTO THE INTERIOR FOR SUNDAY.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY FOR PKZ200-PKZ210-PKZ240.

GALE WARNING FOR PKZ220-PKZ225-PKZ230.

HEAVY FREEZING SPRAY WARNING FOR PKZ240-PKZ245.
&&

NTS OCT 15