Small Craft Advisory 978, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
413 PM AKST SUN DEC 7 2014

.ANALYSIS AND UPPER LEVELS...
THE UPPER LEVEL PATTERN SHOWS A HIGH AMPLITUDE RIDGE THAT EXTENDS
NORTHWARD THROUGH BRITISH COLUMBIA AND THEN BENDS SHARPLY WESTWARD
OVER THE INTERIOR OF ALASKA. A LARGE AREA OF LOW PRESSURE ALOFT IS
OVER THE EASTERN BERING SEA AND WESTERN GULF OF ALASKA. THIS IS
LEADING TO STRONG SOUTHEAST FLOW OVER THE GULF OF ALASKA AND OVER
SOUTHCENTRAL AND SOUTHWEST ALASKA.

THE BIG WEATHER MAKER TODAY IS A STRONG LOW THAT IS CROSSING FROM
THE WESTERN GULF TO THE EASTERN BERING SEA THIS AFTERNOON. THE
OCCLUDED FRONT IS WRAPPED AROUND THE CENTER IN THE VICINITY OF
KODIAK ISLAND AND PROVIDED ENOUGH INSTABILITY TO CAUSE A FEW
THUNDERSTORMS OVER THE KODIAK AREA.

&&

.MODEL DISCUSSION...
MODELS ARE DOING WELL OVERALL HANDLING THE MOVEMENT OF THE TWO
LOWS MOVING THROUGH THE SOUTHWEST GULF AND INTO THE EASTERN BERING
SEA OVER THE NEXT TWO DAYS. THE NAM IS HANDLING THE DETAILS ALONG
THE NORTH GULF COAST WELL. THE NAM IS ALSO SHOWING THE STRONG EAST
TO SOUTHEAST WINDS ALOFT OVER SOUTHCENTRAL ALASKA AND BRISTOL BAY.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (TODAY AND SUNDAY)...

RAIN ACROSS THE GULF AND COASTAL AREAS TAPERS OFF SLIGHTLY LATE
TONIGHT AS ONE STORM SYSTEM EXITS TO THE WEST. ISOLATED POCKETS
OF FREEZING RAIN ACROSS THE INLAND AREAS...FROM ANCHORAGE NORTH
THROUGH THE MATANUSKA AND SUSITNA VALLEYS...WILL CONTINUE TO BE
A THREAT THROUGH TUESDAY NIGHT WITH LITTLE CHANGE IN SURFACE OR
LOW LEVEL TEMPERATURES. A SPECIAL WEATHER STATEMENT WILL BE ISSUED
TO HIGHLIGHT THE ISOLATED NATURE OF THIS THREAT. ANOTHER SURFACE
LOW WILL MOVE INTO THE SOUTHERN GULF EARLY MONDAY MORNING BRINGING
ANOTHER ROUND OF RAIN AND WIND TO THE GULF WATERS AND GULF
COAST...ALTHOUGH THIS SYSTEM WILL BE WEAKER THAN THE ONE WHICH
MOVED THROUGH TODAY. COLDER TEMPERATURES ACROSS THE COPPER RIVER
VALLEY AND THOMPSON PASS WILL KEEP PRECIPITATION MOSTLY SNOW
EXCEPT SOUTHEAST OF GLENNALLEN WHERE TEMPERATURES ARE CLOSER TO
FREEZING.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
THE BULK OF THE PRECIPITATION HAS CLEARED THE KUSKOKWIM DELTA AS
THE UPPER WAVE TRAVERSING THE SOUTHWEST COASTLINE PUSHES WESTWARD
INTO THE BERING...LEAVING PRIMARILY JUST A FEW SHOWERS THAT WILL
TAPER OFF THROUGH TONIGHT AS THE LOW NEAR THE AKPEN MOVES OFF TO
THE WEST AND WEAKENS. THIS WILL ALSO ALLOW GUSTY EAST TO NORTHEAST
WINDS TO GRADUALLY DIMINISH OVERNIGHT. THE NEXT LOW/UPPER WAVE WILL
THEN APPROACH FROM THE SOUTHEAST BY LATE MONDAY...WITH THE
PRECIPITATION ASSOCIATED WITH THIS FEATURE MAINLY CONFINED TO
BRISTOL BAY THROUGH TUESDAY.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
BROAD CYCLONIC FLOW WILL KEEP WIDESPREAD RAIN SHOWERS OVER MUCH OF
THE BERING AND ALEUTIANS FOR THE NEXT SEVERAL DAYS...WITH SNOW
MIXING AT TIMES OVER THE WESTERN HALF OF THE BERING AS COLDER AIR
FILTERS INTO THE REGION IN NORTHERLY FLOW. THE MOST INTENSE
PRECIPITATION WILL BE FOCUSED OVER THE EASTERN BERING THROUGH
MONDAY AS A LOW TRACKS WESTWARD ALONG THE AKPEN TO NEAR DUTCH
HARBOR...WITH GALE FORCE WINDS THROUGH BRISTOL BAY AND ALONG THE
SOUTHWEST COAST GRADUALLY DIMINISHING BY MONDAY MORNING.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
AN UPPER LEVEL HIGH PRESSURE REMAINS OVER THE SIBERIA REGION
RESULTING IN NORTHERLY WINDS THROUGH THURSDAY. BY FRIDAY THE
WESTERN ALEUTIANS WILL HAVE A NORTH PACIFIC GALE FORCE LOW
APPROACH BRINGING SOUTHERLY WINDS WITH RAIN AND GUSTY WINDS.
THIS SYSTEM WILL TRACK EASTWARD INTO THE CENTRAL BERING SEA BY
SATURDAY. THIS WILL BRING GUSTY WINDS WITH WIDESPREAD PRECIPITATION
THROUGHOUT THE BERING SEA AND ALEUTIANS THROUGH THE WEEKEND.
THE TEMPERATURES WILL WARM HEADING INTO THE WEEKEND ALONG THE
ALEUTIANS BEFORE SPREADING OVER INTO THE BERING SEA.

THE SOUTHWEST ALASKA REGION WILL SEE THE REMNANTS OF THE WEAKENING
LOW POSITIONED OVER THE BRISTOL BAY AREA THROUGH THURSDAY. THIS
WILL BRING SHOWERY PRECIPITATION THROUGH THE AREA WITH CONTINUED
OFFSHORE FLOW. THE MODELS BRING ANOTHER NORTH PACIFIC LOW SOUTH OF
THE EASTERN ALEUTIANS BY FRIDAY. THE MODELS STRUGGLE WITH THE
STRENGTH/POSITIONING OF THE LOW AS IT MOVES EASTWARD INTO THE
LOWER EASTERN GULF BY SATURDAY. THE FORECAST CONFIDENCE REMAINS
LOW DUE TO THE MODEL DIFFERENCES WITH THESE SYSTEMS.

THE GULF WILL SEE A GRADUAL WARMING TREND WITH A NORTH PACIFIC
STORM FORCE LOW TRACKING INTO THE LOWER EASTERN GULF BY WEDNESDAY.
THIS LOW WILL TRACK TO THE NORTHERN GULF BY FRIDAY BRINGING
WINDS AND PRECIPITATION ALONG THE NORTHERN GULF COASTLINE WITH
SOME MOISTURE MAKING IT INLAND BEFORE THE SYSTEM DISSIPATES BY
SATURDAY. A SECOND NORTH PACIFIC STORM FORCE LOW WILL TRACK TO THE
SOUTHERN GULF BY SATURDAY BRINGING GALE FORCE WINDS ALONG THE
SOUTHEASTERN ALASKA COASTLINE WITH WIDESPREAD RAIN THROUGHOUT THE
MAJORITY OF THE GULF. THESE SYSTEMS WILL BRING WARMER AIR THROUGH
THE SOUTHCENTRAL ALASKA HEADING INTO THE WEEKEND. THE MODELS HAVE
STRUGGLED WITH THE TIMING AND PLACEMENT OF THESE SYSTEMS.
THEREFORE...THE FORECAST CONFIDENCE REMAINS LOW FOR THE LONG TERM
FORECAST PERIOD.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING 119 120 130 131 132 138 139 150 160 180 185.
         HEAVY FREEZING SPRAY WARNING...180 181.
         FIRE WEATHER...NONE.

&&

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