Small Craft Advisory 497, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
513 AM AKDT THU JUN 11 2015

.ANALYSIS AND UPPER LEVELS...THE BROAD LONGWAVE TROUGH IS FINALLY
STARTING TO SHIFT OFF TO THE EAST THROUGH THE GULF OF ALASKA. THIS
IS A RESULT OF AN AMPLIFYING PATTERN OVER THE WESTERN PACIFIC
CAUSING THE POLAR LOW OVER THE CHUCKCHI SEA TO SHIFT NORTH. AS
THAT LOW SHIFTS TO THE NORTH...IT WILL ALLOW A VERY POTENT RIDGE
FROM THE NORTH PACIFIC TO SURGE TOWARD THE STATE. BUT IN THE
MEANTIME...FLOW ACROSS MUCH OF THE MAINLAND WILL BE NORTHWESTERLY
CAUGHT UP IN BETWEEN THESE TWO LARGE FEATURES. A FEW WEAK
SHORTWAVES ARE CURRENTLY RIDING A 60-70 KT FINGER OF THE JET FROM
THE PRIBILOF ISLANDS THROUGH BRISTOL BAY. THESE WAVES WILL KEEP
SHOWERS IN THE FORECAST FOR MOST OF THE SOUTHERN MAINLAND FOR
THURSDAY. THERE IS ALSO A WIDESPREAD BLANKET OF MARINE STRATUS
STRETCHING FROM THE WESTERN ALEUTIANS INTO BRISTOL AS SOME WARMER
TEMPERATURES CROSS OVER THE COOLER WATERS AND STABILITY INCREASES.

&&

.MODEL DISCUSSION...ALL MODELS REMAIN IN VERY GOOD AGREEMENT WITH
THE TIMING AND STRENGTH OF FEATURES IN THE SYNOPTIC PATTERN. THE
BIGGEST STRUGGLE THEY ARE HAVING IS WITH THE MARINE STRATUS OVER
THE BERING. THE HIGHER RESOLUTION MODELS ARE STARTING TO PICK UP
ON THIS WITH RECENT OBSERVATIONS...BUT THE EARLY MORNING FORECAST
WILL HAVE TO RELY ON SATELLITE AND SURFACE OBS TO HANDLE SOME OF
THIS INITIALLY. BEYOND THIS...THE FORECAST MOSTLY UTILIZED THE
HIGHER RESOLUTION NAM MODEL TO DEAL WITH THE END OF THE WEEK AND
INTO THE WEEKEND. BIGGEST CHANGE WAS TO INCREASE TEMPERATURES AND
OUTFLOW WINDS AS THE HIGH TRULY BUILDS IN.

&&

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

UNSETTLED WEATHER CONTINUES ACROSS SOUTHCENTRAL ALASKA. UPPER
WAVES MOVE WEST ACROSS SOUTHCENTRAL TODAY TRIGGERING SHOWERS AND
EVEN A FEW THUNDERSTORMS OVER THE COPPER RIVER BASIN THIS
AFTERNOON AND EVENING. A FAIRLY STRONG WAVE...WHOSE PASSAGE FRIDAY
USHERS IN A PATTERN CHANGE...BRINGS FAIRLY STEADY RAINS TO THE
NORTHERN SUSITNA VALLEY TONIGHT AND THUNDERSTORMS TO THE COPPER
RIVER BASIN ON FRI. THIS WAVE MOVES EAST/SOUTH OF THE COPPER RIVER
BASIN EARLY SAT. HIGH PRESSURE BUILDS TO THE LEE OF THIS WAVE WEST
OF THE COPPER RIVER BASIN FRI AND THE REMAINDER OF SOUTHCENTRAL
FRI NIGHT. A WARMER...DRIER...AND LOCALLY WINDY PATTERN WILL
SPREAD EAST WITH THE BUILDING RIDGE(BEHIND WAVE). BRISK OUTFLOW
CONDITIONS WILL FIRST BE FELT ACROSS THE EASTERN KENAI PEN WITH
GUSTY WEST TO NORTH WINDS DEVELOPING DURING THE EARLY MORNING
HOURS FRI. THESE CONDITIONS WILL TEND TO HOLD AFTERNOON
SEABREEZES AT BAY AND ALLOW AFTERNOON TEMPS TO GET FAIRLY TOASTY
IN SPOTS. AS THE RIDGE BUILDS EAST FRI NIGHT...BRISK AND GUSTY
OUTFLOW CONDITIONS ARE EXPECTED TO SPREAD TO THE NORTH GULF COAST
AND GAPS IN THE ALASKA RANGE IN THE COPPER RIVER BASIN.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2...TODAY AND
FRI)... SOUTHWEST ALASKA WILL CONTINUE TO BE IN A SHOWERY PATTERN
THROUGH FRIDAY AS A SERIES OF UPPER LEVEL SHORT WAVES MOVE THROUGH
THE REGION. COASTAL FOG WILL BE THE MAIN FEATURE SETTING UP ALONG
BRISTOL BAY AND THE KUSKOKWIM DELTA THIS MORNING...AND PERSISTING
INTO THE WEEKEND. FOGGY CONDITIONS WILL LIKELY ADVECT FURTHER
INLAND OVER THESE AREAS BOTH TONIGHT AND TOMORROW NIGHT...WITH
ONSHORE FLOW PICKING UP OVER THE SOUTHWESTERN COAST.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2...TODAY
AND FRI)... WINDS OVER MUCH OF THE BERING AND ALEUTIANS WILL
REMAIN BRISK INTO THE WEEKEND...AS HIGH PRESSURE CONTINUES TO
BUILD IN OVER THE REGION. WARMER TEMPERATURES AND MORE STABLE
CONDITIONS ARE EXPECTED OVER THE BERING AND ALEUTIANS WITH THIS
PATTERN CHANGE...WHICH WILL KEEP WIDESPREAD FOGGY CONDITIONS
ACROSS MUCH OF THE BERING AND COASTAL WATERS INTO THE WEEKEND. A
FRONT ASSOCIATED WITH THE LOW TRACKING ALONG THE EASTERN KAMCHATKA
COAST WILL BEGIN TO IMPACT THE WESTERN ALEUTIANS THIS
AFTERNOON...THEN CONTINUE EASTWARD OVER THE CENTRAL ALEUTIANS BY
THE WEEKEND. THIS SYSTEM WILL BRING AREAS OF GALE FORCE WINDS AND
RAIN TO THE WESTERN AND CENTRAL ALEUTIANS/BERING OVER NIGHT
TONIGHT THROUGH SATURDAY MORNING.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7...SAT THROUGH WED)... AN
UPPER LEVEL CLOSED HIGH PRESSURE IS POSITIONED OVER THE SHUMAGIN
ISLANDS WITH AN AMPLIFIED RIDGE EXTENDING NORTHWARD THROUGH THE
ALASKA INTERIOR INTO THE NORTH SLOPE BY SATURDAY. THIS CLOSED HIGH
PRESSURE WILL MOVE OVER THE LOWER KUSKOKWIM VALLEY INTO THE MATSU
VALLEY BY SUNDAY. THIS SYSTEM WILL STRENGTHEN AND BECOME
STATIONARY OVER THE SOUTHCENTRAL THROUGH WEDNESDAY. WEAK SHORTWAVE
TROUGHS WILL TRACK NORTHWARD ON THE BACKSIDE OF THE RIDGE BUT WILL
FALL APART AS IT CONTINUES TO RUN INTO THE AMPLIFIED RIDGE. ANY
PRECIPITATION WILL BE ALONG THE KUSKOKWIM DELTA REGION NORTHWARD
ALONG THE COAST THROUGH THE NEXT SEVERAL DAYS. THE MAIN CONCERN
WILL BE THE SIGNIFICANTLY WARMER TEMPERATURES THROUGHOUT THE
ALASKA REGION AS WE HEAD INTO THE MIDDLE OF NEXT WEEK. THESE
WARMER TEMPERATURES WILL BE ACCOMPANIED BY DRIER CONDITIONS AND
LOWER RELATIVE HUMIDITIES THROUGH THE COPPER RIVER BASIN...MATSU
VALLEY AND INTERIOR PORTIONS OF SOUTHWEST ALASKA. THE COPPER RIVER
BASIN AND ALONG THE NORTHERN GULF WILL HAVE NORTHERLY OFFSHORE
WINDS AND WILL LIKELY SEE CLOSE TO RECORD SETTING TEMPERATURES FOR
THE SEWARD AND THE COPPER RIVER BASIN REGION. THERE WILL LIKELY BE
FIRE WEATHER CONCERNS AS RELATIVE HUMIDITIES LOWER FOR THE MATSU
VALLEY AND THE COPPER RIVER BASIN REGIONS THROUGH THE WEEKEND AND
INTO THE MIDWEEK. MEANWHILE...THE WESTERN ALEUTIANS WILL HAVE THE
REMNANTS OF THE KAMCHATKA LOW AND WILL CONTINUE TO BRING SOUTHERLY
GALE FORCE WINDS ACCOMPANIED BY RAIN/FOG INTO THE WESTERN/CENTRAL
BERING SEA THROUGH THIS WEEKEND BEFORE DIMINISHING BY MONDAY. THEN
HIGH PRESSURE WILL BEGIN TO BUILD OVER THE BERING SEA THROUGH
MIDWEEK. THIS WILL BRING LOW STRATUS AND FOG THROUGHOUT THE BERING
AND ALONG THE SOUTHWEST COASTLINE HEADING INTO NEXT WEEK.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...177 178.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...MSO
SOUTHCENTRAL ALASKA...RMC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...TP
LONG TERM...PD

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE ANCHORAGE AK
112 PM AKDT THU JUN 11 2015

...WARM TEMPERATURES THIS WEEKEND INTO THE MIDDLE OF NEXT WEEK...

AKZ101-111-121-125-131-135-141-145-171-122000-
ANCHORAGE-MATANUSKA VALLEY-WESTERN KENAI PENINSULA-
WESTERN PRINCE WILLIAM SOUND-NORTHEAST PRINCE WILLIAM SOUND-
SOUTHEAST PRINCE WILLIAM SOUND-COPPER RIVER BASIN-SUSITNA VALLEY-
KODIAK ISLAND-
INCLUDING THE CITIES OF...ANCHORAGE...EAGLE RIVER...INDIAN...
EKLUTNA...PALMER...WASILLA...SUTTON...CHICKALOON...KENAI...
SOLDOTNA...HOMER...COOPER LANDING...WHITTIER...SEWARD...
GIRDWOOD...MOOSE PASS...VALDEZ...THOMPSON PASS...CORDOVA...
GLENNALLEN...EUREKA...MCCARTHY...PAXSON...SLANA...TALKEETNA...
WILLOW...CANTWELL...KODIAK CITY
112 PM AKDT THU JUN 11 2015

A STRONG RIDGE OF HIGH PRESSURE BUILDING FIRST OVER SOUTHWEST
ALASKA ON FRIDAY AND THEN SHIFTING EAST AND STRENGTHENING OVER
MAINLAND ALASKA THROUGH THE WEEKEND WILL START A RATHER
SIGNIFICANT SHIFT TOWARDS A MORE SUMMERY WEATHER PATTERN.

TEMPERATURES WILL BEGIN GRADUALLY WARMING ON FRIDAY THEN CLIMB
MORE QUICKLY TO WELL ABOVE SEASONAL NORMALS FOR SATURDAY AND
SUNDAY. ADDITIONALLY...A TROUGH ALONG THE NORTH GULF COAST WILL
PRODUCE DRY OFFSHORE FLOW AND SUPPRESS AFTERNOON SEA BREEZES
ALLOWING THE TYPICALLY COOLER COASTAL LOCATIONS TO BECOME QUITE
WARM AS WELL.

THE WARM AND DRY PATTERN IS EXPECTED TO CONTINUE THROUGH THE FIRST
HALF OF NEXT WEEK AS THE STRONG BLOCKING RIDGE PERSISTS AND IS
EXPECTED TO BRING SOME OF THE WARMEST TEMPERATURES SO FAR THIS
YEAR.