Small Craft Advisory 354, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
126 PM AKDT SUN APR 27 2014

.ANALYSIS AND UPPER LEVELS...
THERE IS CURRENTLY A WEAKENING VERTICALLY STACKED LOW SOUTH OF
KODIAK ISLAND WITH AN ASSOCIATED FRONT STRETCHED OUT AND STALLED
ALONG THE NORTH GULF COAST. STEADY RAIN ALONG THE EASTERN KENAI
PENINSULA HAS GIVEN WAY TO SHOWERS AS THE FRONT CONTINUES TO
WEAKEN AND DRIFT SOUTHWARD. INCREASING AMOUNTS OF SUNSHINE ARE
BREAKING OUT ACROSS INTERIOR AREAS OF THE MAINLAND...ALLOWING
ABOVE NORMAL TEMPERATURES TO SPREAD BACK INTO THE REGION. OUT
WEST...A RIDGE BUILDING OVER THE CENTRAL BERING IS RESULTING IN
AREAS OF MARINE FOG/STRATUS OVER MUCH OF THE AREA. MEANWHILE...A
FAIRLY GARDEN-VARIETY FRONT OVER THE WESTERN BERING IS WEAKENING
AND LIFTING NORTHWARD AS HIGH PRESSURE CONTINUES TO INTENSIFY.

&&

.MODEL DISCUSSION...
A PATTERN CHANGE IS UNDERWAY ACROSS THE ALASKA DOMAIN AS THE
LONGWAVE TROUGH AND STATIONARY LOW SOUTH OF KODIAK ARE WEAKENING
AND BEGINNING TO MOVE TO THE SOUTHEAST AND AWAY FROM THE STATE.
INSTEAD...THE RIDGE OVER THE CENTRAL BERING HAS ITS SIGHTS SET ON
THE MAINLAND...AND WILL STRENGTHEN DRAMATICALLY IN THE COMING DAYS
EN ROUTE TO BECOMING A HIGH-LATITUDE BLOCKING RIDGE/HIGH OVER THE
MAINLAND. CONFIDENCE AND MODEL AGREEMENT IN THIS EVOLUTION
CONTINUES TO INCREASE...WHICH WILL RESULT IN AN EXTENDED PERIOD OF
SUNNY AND ABOVE-NORMAL TEMPERATURES FOR THE MAINLAND AND PANHANDLE.
THE ECMWF AND GFS ARE BOTH TRENDING STRONGER WITH THE CLOSED HIGH
OVER THE STATE BY THE END OF THE WEEK...AND AS A RESULT ARE
TRENDING FURTHER WEST WITH A LOW PRESSURE SYSTEM MOVING INTO THE
BERING BY THE END OF THE WEEK. OVERALL THE ECMWF AND GFS ARE IN
GOOD AGREEMENT AND ARE THE FAVORED MODELS TODAY. THE MOST
SUBSTANTIAL CHANGES TO THE FORECAST ARE TO ENHANCE SEA BREEZES
EXPECTED TO DEVELOP THIS WEEK AND ALSO TO INCREASE TEMPERATURES AS
THE HIGH SETS UP SHOP.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...
AS THE COMPLEX LOW IN THE SOUTHWEST GULF PULLS AWAY OVER THE NEXT
FEW DAYS CLOUD-COVER WILL STEADILY DECREASE FROM NORTH TO SOUTH. A
SHORTWAVE WITH ASSOCIATED WEAK SURFACE LOW WILL BE ROTATING
THROUGH THE NORTHERN GULF AROUND THE OVERALL CIRCULATION TONIGHT.
PRESSURE RISES BEHIND THIS FEATURE COUPLED WITH OVERALL RISING
PRESSURES AS THE BIG LOW MOVES AWAY WILL SEND A SURGE OF MASS
THROUGH TURNAGAIN ARM AND THE KNIK RIVER VALLEY TOMORROW MORNING
AND AFTERNOON. THESE WILL LIKELY AFFECT PORTIONS OF UPPER COOK
INLET TOMORROW. IN THE MATANUSKA VALLEY...WITH LOW RELATIVE
HUMIDITY VALUES AGAIN EXPECTED...THESE WINDS MAY LEAD TO RED FLAG
CONDITIONS. AS HIGH PRESSURE AND WARMER TEMPERATURES MOVE INTO THE
AREA IN A MAJOR WAY BY MIDWEEK ADDITIONAL FIRE WEATHER CONCERNS
WILL NEED TO BE CLOSELY MONITORED. BY FRIDAY EVENING...THE 500
HPA HEIGHT FIELD AS WELL AS 850 HPA TEMPERATURES ARE BOTH PROGGED
TO APPROACH 3 STANDARD DEVIATIONS ABOVE NORMAL. THIS WILL LEAD TO
TEMPERATURES 10-15 DEGREES ABOVE NORMAL FOR MANY LOCATIONS.

SOUTHWEST ALASKA...
AS THE BIG LOW PULLS AWAY INTO THE PACIFIC THE SKIES WILL SHOW A
SIMILAR CLEARING TREND TO SOUTHCENTRAL. AS THIS HAPPENS...SURFACE
WINDS WILL SWITCH AROUND TO THE MORE SOUTHERLY/ONSHORE...WHICH
DIRECTION. THIS WILL BRING INCREASED MOISTURE INTO THE ATMOSPHERE
AND LIKELY LEAD TO INCREASING AFTERNOON/EVENING SHOWERS ACROSS THE
REGION BY MIDWEEK. OTHERWISE...SUNNY AND WARM CONDITIONS WILL ALSO
PREVAIL FOR MUCH OF THE UPCOMING WEEK.

BERING SEA/ALEUTIANS...
AS HIGH PRESSURE BUILDS INTO AND THEN CLOSES OFF OVER MAINLAND
ALASKA THE EASTERN HALF OF THE BERING WILL FALL PRIMARILY UNDER
THE INFLUENCE OF THESE HIGHER PRESSURES. WHILE THIS WILL KEEP
STORMS AWAY FROM THE REGION...IT WILL ALSO LEAD TO THE FIRST
MULTI-DAY WIDESPREAD MARINE FOG/STRATUS OUTBREAK OF THE SUMMER
SEASON. MEANWHILE...THE WESTERN BERING WILL SEE A LONGWAVE TROUGH
AMPLIFY UPSTREAM OF THE BIG RIDGE...WHICH WILL HELP STEER A SERIES
OF STORM SYSTEMS INTO THE AREA THIS WEEK. NONE OF THESE SYSTEMS
LOOKS PARTICULARLY STRONG...BUT THE UNSETTLED WEATHER WILL KEEP
TEMPERATURES NEAR OR BELOW NORMAL WITH PLENTY OF CLOUDS TO GO
AROUND.

&&

.LONG TERM FORECAST...
NOT SURPRISINGLY...THE BIG STORY IS THE HIGH PRESSURE THAT WILL
BECOME ENTRENCHED OVER THE MAINLAND. LONG RANGE MODELS ARE
SUGGESTING THIS FEATURE COULD PERSIST THROUGH THE FIRST WEEK OF
MAY AND POSSIBLY LONGER. THUS...EXPECT OVERALL WARM...DRY...AND
MOSTLY SUNNY CONDITIONS FOR MANY PARTS OF THE STATE FOR THE
FORESEEABLE FUTURE.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 177.
FIRE WEATHER...FIRE WEATHER WATCH 111.

&&

AMD APR 14