High Wind in Alaska, January 6, 2016

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
508 AM AKST WED JAN 6 2016

.ANALYSIS AND UPPER LEVELS...
TWO LARGE FEATURES ALOFT...A CLOSED HIGH PRESSURE AND A CLOSED LOW
PRESSURE DOMINATE THE FLOW PATTERN ALOFT OVER THE GREAT LAND. THE
RIDGING AND CLOSED HIGH PRESSURE IS SET UP OVER THE YUKON
TERRITORY...STRETCHING ALL THE WAY UP INTO THE ARCTIC. THE CLOSED
LOW PRESSURE IS CENTERED OVER THE KAMCHATKA
PENINSULA...ENCOMPASSING MOST OF THE BERING SEA. THE ACTIVE
WEATHER IS MOSTLY BETWEEN THESE TWO FEATURES...SENDING A SOUTH TO
NORTH STORM TRACK FROM THE NORTH PACIFIC THROUGH WESTERN ALASKA. WHILE
THE JET STREAM IS WELL TO THE SOUTH IN THE MID-LATITUDES IT IS
SPAWNING A STRONG SURFACE LOW NEAR THE CENTRAL ALEUTIANS. THIS
SYSTEM LOOKS TO BE NEARING PEAK INTENSITY EARLY THIS MORNING IN
THE SUB 950 MB RANGE. THAT STORM IS THE STRONGEST FEATURE ON THE
MAP THIS MORNING WITH A STORM FORCE WIND FIELD. OTHERWISE THERE
ARE SOME LINGERING SHOWERS UNDER A WEAK JET ALOFT OVER THE
KUSKOKWIM VALLEY AND DECREASING CLOUDS AS A WHOLE ACROSS THE
MAINLAND. OVER SOUTHCENTRAL...DECREASING CLOUDS AND SEASONABLE
TEMPERATURES ARE MOSTLY THE EXTENT OF ACTIVE WEATHER THOUGH A WEAK
PRESSURE GRADIENT FORCING OUTFLOW WINDS IS BEGINNING TO SET UP
THIS MORNING OVER THE NORTH GULF COAST.

&&

.MODEL DISCUSSION...
THE MAIN FEATURE TO DISCUSS IS THE DEVELOPING SYSTEM OVER THE
CENTRAL ALEUTIANS. FROM A PRESSURE AND TRACK
PERSPECTIVE...GUIDANCE IS IN GOOD AGREEMENT WITH THE SYSTEM MOVING
NORTHWARD IN THE BERING SEA. THE ONLY DIFFERENCES THAT ARISE ARE
SOME SLIGHT FRONTAL TIMING/STRENGTH ISSUES. BOTH DOMAINS
PREFERRED THE NAM SOLUTION IN THE SHORT TERM.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
HIGH PRESSURE OVER THE MAINLAND IN COMBINATION WITH A LOW PRESSURE
TROUGH OVER THE GULF WILL CONTINUE OUTFLOW WINDS OVER THE EASTERN
KENAI AND NORTH GULF COAST INTO THE AFTERNOON HOURS TODAY. A WEAK
SURFACE LOW MOVES SLOWLY WEST ACROSS THE GULF TONIGHT INCREASING
EASTERLY WINDS ACROSS THE NORTHERN GULF COASTAL MARINE AREAS
BEFORE IT DISSIPATES IN THE WESTERN GULF THU. A DEVELOPING NORTH
PACIFIC LOW AND ITS ASSOCIATED FRONTAL TROUGH (OCCLUDED FRONT)
MOVE NORTH TOWARD THE AK PEN BRINGING GALES TO LOCAL STORM
CONDITIONS ALONG WITH RAIN TO THE WESTERN GULF THU AFTERNOON/NIGHT.
AN UPPER WAVE HEADING NORTH ACROSS THE GULF THU MOVES OVER PRINCE
WILLIAM SOUND THU AFTERNOON AND INTO THE NORTHERN COPPER RIVER
BASIN THU NIGHT. THIS FEATURE WILL BRING SNOW/SHOWERS OR MIXED
PRECIPITATION TYPES.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
THE MAIN ACTIVITY IN THE AREA WILL STAY OVER THE BERING THROUGH
TONIGHT LEAVING WEAK SOUTHEASTERLY FLOW OVER SOUTHWEST ALASKA. THE
DRIER AIR ASSOCIATED WITH THIS FLOW WILL ALSO KEEP PRECIPITATION
AWAY UNTIL THURSDAY WHEN A NEW FRONT PUSHES UP FROM THE SOUTH
FROM A NORTH PACIFIC LOW. THIS FRONT WILL BRING A MIX OF RAIN AND
SNOW ALONG THE COAST AND ON THE SOUTH FACING SIDE OF THE
MOUNTAINS.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
THE MAIN LOW OVER THE AREA IS A DEEP LOW THAT LOOKS TO BE SUB 950
MB AND IS FAST APPROACHING THE CENTRAL ALEUTIANS. THE FRONT HAS
MOVED OVER THE EASTERN ALEUTIANS AND IS BRINGING WARNING LEVEL
WINDS TO NIKOLSKI THAT WILL SPREAD EAST THIS MORNING. WINDS FOR
THE EASTERN ALEUTIANS WILL DIMINISH THIS AFTERNOON AS THE
STRONGEST CORE OF WINDS WEAKENS AND MOVES OFF TO THE NORTH TOWARDS
THE PRIBILOF ISLANDS. AS THE LOW MOVES INTO THE SOUTHERN BERING
AND THE COLD AIR ADVECTION ON THE WEST SIDE MOVES OVER THE ADAK
AREA...WARNING LEVEL WINDS ARE ALSO EXPECTED TO IMPACT THE AREA.
THESE WINDS WILL DIMINISH OVERNIGHT AS THE LOW MOVES NORTH. THE
LOW WILL THEN TRACK OFF TO THE NORTHWEST LEAVING SCATTERED RAIN
AND SNOW SHOWERS BEHIND THAT WILL TRANSITION OVER TO ALMOST ALL
SNOW ON THURSDAY.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...

ON FRIDAY A SLOWLY WEAKENING LOW WILL CONTINUE TO TRACK SOUTH OF
KODIAK ISLAND AND CROSS THE AKPEN INTO THE SOUTHEASTERN
BERING...BRINGING GALE FORCE WINDS FROM THE WESTERN GULF TO THE
EASTERN BERING/SOUTHWEST COAST. WHILE THERE REMAINS UNCERTAINTY
IN THE EXACT TRACK OF THIS LOW...CONFIDENCE IS INCREASING THAT
THIS SYSTEM WILL BRING STORM FORCE WINDS INTO SHELIKOF STRAIT AND
POSSIBLY THE BARREN ISLANDS ON FRIDAY WHEN A TIGHT PRESSURE
GRADIENT SETS UP AS THE LOW PASSES TO THE SOUTH. GOOD CONFIDENCE
ALSO REMAINS THAT PRECIPITATION FROM THIS SYSTEM WILL REMAIN
LARGELY CONFINED TO THE GULF AND SOUTHWEST COAST...WHILE
DOWNSLOPING WILL KEEP INTERIOR SOUTHCENTRAL AND SOUTHWEST MAINLAND
CLOUDY BUT DRY.

FROM THE WEEKEND INTO NEXT WEEK...LITTLE CHANGE IN THE
WEATHER PATTERN IS EXPECTED...WITH A CONTINUATION OF THE WEATHER
PATTERN THAT HAS BROUGHT WARM AIR AND PLENTIFUL SUBTROPICAL
MOISTURE INTO MAINLAND ALASKA FOR THE LAST WEEK. THE MOST ACTIVE
STORM TRACK IS GOING TO KEEP MODERATE OR PERHAPS EVEN STRONG
INTENSITY STORMS MOVING NORTHWARD FROM THE PACIFIC AND INTO THE
EASTERN HALF OF THE BERING AND POSSIBLY BRUSHING SOUTHWEST ALASKA.
THE BERING/ALEUTIAN BASIN WILL BEAR THE BRUNT OF THE ACTIVE
WEATHER FOR THE NEXT WEEK WITH MULTIPLE ROUNDS OF STRONG WINDS AND
HEAVY PRECIPITATION. MEANWHILE...THE SOUTHWEST MAINLAND WILL SEE
MULTIPLE BUT RELATIVELY MINOR ROUNDS OF PRECIPITATION (MOSTLY
RAIN) DURING THE PERIOD WITH WINDS STAYING MAINLY ALONG THE COAST.
FURTHER TO THE EAST...A SMALL BUT MEANINGFUL DIFFERENCE FROM LAST
WEEK'S PATTERN IS THAT THE JET STREAM MOVING UP INTO THE STATE IS
GOING TO BE A BIT MORE SOUTHEASTERLY THAN IT WAS LAST WEEK (WHEN
IT WAS NEARLY FROM THE DUE SOUTH). THIS WILL GENERALLY FAVOR
NORTHERLY WINDS AT THE LOWEST LEVELS OF COOK INLET...KEEPING THE
MAIN POPULATION CENTERS DRIER AND COOLER.

WHILE THE MODELS AGREE ON THE OVERALL WEATHER PATTERN THEY
DISAGREE SIGNIFICANTLY ON INDIVIDUAL SYSTEMS BEYOND THURSDAY
NIGHT. THIS YIELDS VERY LITTLE PREDICTABILITY ON SOME POTENTIALLY MAJOR
SHORTWAVES THAT WILL PINWHEEL AROUND THE LONGWAVE TROUGH IN THE
BERING SEA THIS WEEKEND INTO NEXT WEEK. THE GFS BRINGS SEVERAL
STRONG STORMS THROUGH THE AKPEN/SOUTHWEST ALASKA REGION DURING THE
EXTENDED FORECAST TIMEFRAME...WHEREAS THE ECMWF IS SUBSTANTIALLY
WEAKER WITH THE INDIVIDUAL STORMS AND DOES NOT EVEN AGREE WITH THE
GFS ON THE NUMBER OF STORMS EXPECTED TO DEVELOP DURING THE NEXT
WEEK. WE WILL CLOSELY WATCH FOR THE POSSIBILITY THAT ANY ONE OF
THESE STORMS COULD PRODUCE WARNING-LEVEL CONDITIONS FOR WINDS OR
PRECIPITATION.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WARNING 185 187.
MARINE...STORM 170-177 179 185.
         GALE 155 165 178 180 181
         HEAVY FREEZING SPRAY 180 181

&&

SYNOPSIS AND MODEL DISCUSSION...ML
SOUTHCENTRAL ALASKA...RMC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK
LONG TERM...CC/DEK