Brisk Wind Advisory 14, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
521 AM AKST SAT FEB 14 2015

.ANALYSIS AND UPPER LEVELS...
VERY BROAD CYCLONIC FLOW EXISTS IN THE UPPER LEVELS FROM THE
CENTRAL BERING SEA THOUGH THE GULF OF ALASKA...EXTENDING WELL
SOUTH INTO THE MID-LATITUDES. THE LONG-WAVE REMAINS CENTERED WEST
OF UNALASKA WHILE EMBEDDED SHORTWAVES RIDE THE JET FROM THE
CENTRAL PACIFIC TOWARD THE GULF. THE WEST COAST NORTH AMERICAN
RIDGE HAS BEEN AT LEAST TEMPORARILY SUPPRESSED BY THE WAVE
TRAIN...BUT RIDGING STILL SITS OVER THE INTERIOR BENDING BACK INTO
THE SOUTHWEST MAINLAND. THE CURRENT WAVE-DU-JOUR ENCOMPASSES THE
WESTERN GULF BUT DOESN'T HAVE AN OVERLY IMPRESSIVE WIND FIELD
ASSOCIATED WITH IT. THE PRECIPITATION SHIELD IS MAINLY IMPACTING
THE WESTERN PRINCE WILLIAM SOUND ZONE AND TO A LESSER EXTENT THE
NORTH GULF COAST. NO PRECIPITATION IS CURRENTLY MAKING IT OVER THE
MOUNTAINS AS THE COOK INLET REGION REMAINS DOWNSLOPED. FOG AND LOW
STRATUS HAS NOT BEEN AN ISSUE TONIGHT WITH INCREASING LOW LEVEL
WINDS AND UPPER LEVEL CLOUD COVER.

&&

.MODEL DISCUSSION...
GUIDANCE IS IN GREAT AGREEMENT WITH THE UPPER LEVEL HEIGHT
FIELDS...LOW LEVEL PRESSURE FIELDS AS WELL AS THE WEAKENING OF THE
UPPER LEVEL SHORTWAVE AS IT MOVES INLAND. THE BIGGEST QUESTION
HOWEVER...WHAT DO THE PRECIPITATION FIELDS DO? FOR THE MOST PART
GUIDANCE IS SIGNALING A DOWNSLOPE REGIME SETTING UP BUT THE CORE
OF THE CROSS-BARRIER FLOW LOOKS BOTH EASTERLY AND NEAR OR ABOVE
MOUNTAIN TOP LEVEL...BOTH OF WHICH BODE WELL FOR SOME
PRECIPITATION SLOPPING OVER THE MOUNTAINS. THIS SIGNAL IS SHOWN BY
THE GFS AND ECMWF WHEREAS THE HIGHER RESOLUTION GUIDANCE KEEPS THE
ANCHORAGE AREA MAINLY DRY UNTIL UPPER TROUGH PASSAGE. THE BIGGER
STORY COMES LATE SUNDAY INTO MONDAY AS A STRONG SYSTEM DEVELOPS IN
THE NORTH PACIFIC AND SENDS A STRONG FRONT INTO THE GULF.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
THE LOW PRESSURE SYSTEM IN THE GULF WILL SLOWLY WEAKEN TODAY AND
MOVE INTO COOK INLET. EARLY ON TODAY PRECIPITATION WILL BE RAIN
FALLING MAINLY ALONG THE NORTH GULF COAST AND WESTERN PRINCE
WILLIAM SOUND REGION. IN THE AFTERNOON HOURS RAIN MIXED WITH SNOW
WILL START TO WORK SOUTH TO NORTH OVER THE KENAI PENINSULA.
ANCHORAGE WILL STAY MOSTLY DRY BUT A WINTRY MIX OF PRECIPITATION
COULD MAKE IT OVER THE MOUNTAINS ON THE EAST SIDE OF TOWN AS A
WARM LAYER REMAINS IN PLACE...BUT SHOULD WET-BULB OUT THROUGH THE
NIGHT. THE BEST CHANCE FOR PRECIPITATION COMES OVERNIGHT WHEN THE
UPPER TROUGH SWINGS THROUGH. THIS SHOULD BRING SOUTHERLY WINDS OFF
TURNAGAIN ARM AND BRING WARMER TEMPERATURES AND RAIN TO MOST OF
ANCHORAGE EXCEPT FOR MAYBE THE EAST/NORTHEAST SIDE. DRIER
CONDITIONS AND SOUTHEASTERLY WINDS WILL PERSIST ON SUNDAY. LATE
SUNDAY INTO MONDAY A STRONG FRONT ENTERS THE GULF.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...THE WEATHER
THIS MORNING IS FAIRLY QUIET OVER SOUTHWEST ALASKA WITH UPPER
LEVEL RIDGING OVER THE MAINLAND. A TROUGH EXTENDING FROM THE LOW
IN THE EASTERN ALEUTIANS TO THE LOW IN THE GULF CURRENTLY
STRETCHES ACROSS THE ALASKA PENINSULA AND WILL CONTINUE TO BRING
PRECIPITATION TO THAT AREA TODAY. THE TROUGH WILL START LIFTING
NORTH THIS EVENING AS THE GULF LOW SWINGS INLAND AND NORTH
BRINGING SCATTERED TO NUMEROUS SHOWERS TO THE BRISTOL BAY AREA
THIS EVENING AND THE KUSKOKWIM ZONES LATER TONIGHT.

THE NEXT RATHER POTENT FRONTAL SYSTEM WILL APPROACH THE ALASKA
PENINSULA ON SUNDAY...CROSS INTO BRISTOL BAY SUNDAY NIGHT WITH THE
SURFACE LOW FOLLOWING MONDAY. THE BIGGEST IMPACT WITH THIS FRONTAL
SYSTEM FOR SOUTHWEST ALASKA WILL LIKELY BE THE STRONG EASTERLY
WINDS ACCOMPANYING IT WITH THE POTENTIAL FOR ACCELERATION THROUGH
GAPS AND PASSES AS WELL AS DOWNSLOPING DOWN THE LEE SIDE OF THE
ALASKA AND ALEUTIAN RANGES. ADDITIONALLY THE FRONT WILL BRING A
BROAD AREA OF PRECIPITATION AS WELL AS WARMING CONDITIONS WITH
SNOW MIXING OVER TO RAIN IN MOST AREAS WITH THE POSSIBLE EXCEPTION
OF THE LOWER KUSKOKWIM VALLEY WHERE COLD AIR WILL PERSIST LONGER
KEEPING SNOW THE PREDOMINANT PRECIPITATION TYPE WITH THE
POSSIBILITIES FOR SOME PATCHY FREEZING RAIN AS THE WARM
OVERRUNNING INCREASES.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...FOR THE
BERING SEA AND ALEUTIANS NORTH TO NORTHEAST WINDS PERSIST WITH
SNOW AND RAIN OVER THE EASTERN AND CENTRAL ALEUTIANS TAPERING TO
SCATTERED SHOWERS FURTHER WEST. THE CURRENT SURFACE LOW WILL
WEAKEN AND DRIFT SOUTHWEST TO BE REPLACED BY THE NEW STRONGER LOW
HEADED FOR UNIMAK PASS MONDAY MORNING.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
AN UPPER LEVEL CLOSED LOW WILL BE LOCATED NEAR THE SHUMAGIN
ISLANDS BY MONDAY WITH AN ASSOCIATED TROUGH EXTENDING JUST SOUTH
OF KODIAK ISLAND. THESE FEATURES ARE REFLECTED AT THE SURFACE WITH
A STORM FORCE LOW JUST SOUTH OF DUTCH HARBOR EARLY MONDAY MORNING
AND A WEATHER FRONT THROUGH THE WESTERN GULF. THIS WILL BRING
ABUNDANT MOISTURE WITH HEAVY RAIN AT TIMES TO THE WESTERN/NORTHERN
GULF AND SPREAD INLAND BY MONDAY AFTERNOON. THE ANCHORAGE BOWL
AND WESTERN KENAI PENINSULA WILL HAVE DRIER CONDITIONS DUE TO
DOWNSLOPING. THE PRESSURE GRADIENT WILL STRENGTHEN RESULTING IN
GUSTY WINDS THROUGH THE TURNAGAIN ARM...THE BARREN ISLANDS AND GAP
WINDS THROUGH THE ALASKA RANGE. THE GFS/EC MODELS ARE IN BETTER
AGREEMENT WITH THE PLACEMENT OF THE NORTH PACIFIC LOW POSITIONED
NEAR DUTCH HARBOR...EXCEPT FOR THE NAM BEING THE OUTLIER IN
PUSHING THIS SYSTEM FASTER AND FARTHER NORTH INTO THE BERING SEA
ON MONDAY. THIS LOW WILL TRACK NEAR THE PRIBILOF ISLAND LATE
MONDAY AND BECOME ELONGATED WITH A SECONDARY LOW FORMING NORTH OF
NUNIVAK ISLAND BY TUESDAY. THIS WILL BRING GALE FORCE WINDS IN THE
EASTERN BERING SEA...WARMER TEMPERATURES AND INTO THE SOUTHWEST
ALASKA REGION. THE NEXT NORTH PACIFIC LOW WILL TRACK INTO THE
SOUTHERN GULF BY WEDNESDAY BRINGING MORE MOISTURE/PRECIPITATION TO
THE NORTHERN GULF AND ALONG THE COASTLINES. THIS WILL BRING GALE
FORCE WINDS TO THE NORTHERN GULF AND ALONG THE COAST THROUGH
WEDNESDAY. THE GFS MODEL TRACKS THE LOW NEAR SEWARD...VERSUS THE
ECMWF MODEL TRACKING THE LOW NEAR YAKUTAT BY THURSDAY. THE GFS STORM
TRACK WILL BRING MORE PRECIPITATION TO SOUTHCENTRAL REGION...WHILE
THE ECMWF STORM TRACK WILL BRING LESS PRECIPITATION. THE GULF WILL
REMAIN IN SOUTHERLY FLOW THROUGH FRIDAY. THE BERING SEA WILL HAVE
PREDOMINANT NORTHERLY FLOW WITH HIGH PRESSURE OVER THE EASTERN
SIBERIA REMAINING IN PLACE HEADING INTO THE WEEKEND. BY FRIDAY
THERE WILL BE A NORTH PACIFIC LOW APPROACHING THE CENTRAL
ALEUTIANS WITH MORE WARM BEING PUSHED INTO THE ALEUTIAN CHAIN
BEFORE SPILLING OVER INTO THE CENTRAL/EASTERN BERING SEA HEADING
INTO THE WEEKEND.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING...120 130 131 138 150 155 160 165 170 172
                        175 177 180.
         STORM WARNING...132 136 137.
         HEAVY FREEZING SPRAY WARNING...185.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...MTL
SOUTHCENTRAL ALASKA...MTL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JR
LONG TERM...PLD