Small Craft Advisory 329, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
502 PM AKDT WED APR 13 2016

.ANALYSIS AND UPPER LEVELS...

AN UPPER LEVEL LOW CONTINUES TO SPIN IN THE SOUTHEAST GULF OF
ALASKA...WITH A RETROGRADING UPPER LEVEL HIGH RETROGRADING WEST
FROM THE YUKON TO THE ALCAN BORDER AREA ALONG THE EASTERN ALASKA
RANGE AND WITH RIDGE AXIS STRETCHING TO THE COOK INLET REGION.
BETWEEN THESE TWO FEATURES...AN EXPANSIVE AREA OF MID- AND HIGH-
LEVEL CLOUDS PREDOMINATES OVER SOUTHCENTRAL ALASKA...WITH A FEW
ISOLATED RAIN SHOWERS ARE MOVING ALONG THE NORTH GULF AND COASTAL
AREAS TOWARD THE KENAI PENINSULA.

OUT WEST...A STRETCHED-OUT UPPER RIDGE PERSISTS WEST-EAST ACROSS
THE CENTRAL BERING...BETWEEN A SMALL UPPER LOW OVER THE NORTHERN
BERING AND AN EXPANSIVE UPPER LOW CENTERED SOUTH OF THE CENTRAL
ALEUTIANS.

AT THE SURFACE...A GALE-FORCE FRONT LIES DRAPED ACROSS THE CENTRAL
ALEUTIANS BUT IS BEGINNING TO WEAKEN AS IT PIVOTS AROUND THE
SURFACE LOW CENTER MOVING QUICKLY WEST-TO-EAST ACROSS THE NORTH
PACIFIC TO THE SOUTH OF THE ALEUTIANS. A WEAK SURFACE LOW IS
STACKED UNDER THE UPPER LEVEL LOW IN THE SOUTHEAST GULF AND WILL
MAINLY DRIFT NORTHWEST BEFORE DISSIPATING TONIGHT.

&&

.MODEL DISCUSSION...
GUIDANCE REMAINS LOCKED IN ON THE OVERALL SYNOPTIC PATTERN IN THE
SHORT TERM AS THE LARGE NORTH PACIFIC LOW SKIRTS THE ALEUTIAN
CHAIN AND MOVES TO A POSITION SOUTH OF KODIAK ISLAND FRIDAY...WITH
WEAK UPPER RIDGING OVER THE SOUTHERN INTERIOR OF THE STATE. MODELS
ARE ALSO KEYING IN WELL ON A SOLID GALE-FORCE FRONT ENTERING THE
WESTERN ALEUTIANS AND SOUTHWEST BERING LATE FRIDAY.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
THE WEAKENING LOW IN THE GULF IS STILL BRINGING SHOWERS TO THE
AREA...PRIMARILY AROUND THE NORTH GULF COAST. THESE LIGHT SHOWERS
WILL CONTINUE INTO FRIDAY WHEN A FRONT WILL COME UP FROM THE SOUTH
FROM THE LOW APPROACHING THE AREA FROM THE WEST. THE FRONT WILL
BRING MORE RAIN TO COASTAL AREAS WITH THE POSSIBILITY OF SOME
SHOWERS MAKING IT PAST THE COASTAL MOUNTAINS.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
ANOTHER BLUEBIRD EVENING OVER MUCH OF THE MAINLAND AS WEAK RIDGING
ALOFT KEEPS MAJOR WEATHER SYSTEMS AWAY FROM THE AREA. A WEAK
DISTURBANCE COMING FROM COOK INLET WILL BEGIN TO SPREAD CLOUD
COVER AND A CHANCE FOR RAIN SHOWERS OVER THE BRISTOL BAY AREA
TONIGHT. CLOUDS WILL ALSO INCREASE ALONG THE ALASKA PENINSULA AND
KUSKOKWIM DELTA AS A PACIFIC SYSTEM AND FRONT APPROACH THE AREA.
THIS SYSTEM IS WEAKENING ON THE WHOLE AND WILL MOSTLY STAY AWAY
FROM THE MAINLAND...HOWEVER...IT WILL AID IN SPREADING CLOUD COVER
OVER THE AREA...AND ENCOURAGING SEVERAL UPPER DISTURBANCES FROM
THE GULF TO COME OVER THE AREA. THE BEST CHANCE FOR PRECIPITATION
WILL BE ALONG THE ALASKA PENINSULA WHERE THE FRONT WILL STALL AND
DIE TONIGHT INTO THURSDAY AFTERNOON. THE REMAINDER OF THE BRISTOL
BAY AREA WILL SEE SOME RAIN SHOWERS IN THE MORNING AS THE FIRST
DISTURBANCE TRAVERSES THE AREA THEN AFTERNOON/EVENING RAIN SHOWERS
AS DIURNAL INSTABILITY PROMOTES THEM. THE SECOND DISTURBANCE WILL
COME IN LATE THURSDAY EVENING...POTENTIALLY LINGERING
SHOWERS...BUT SHOWER COVERAGE WILL DECREASE OVERNIGHT. LATE
THURSDAY INTO FRIDAY...OFFSHORE FLOW AND DRIER CONDITIONS WILL
PERSIST FOR MOST OF THE MAINLAND ON FRIDAY WITH A CHANCE FOR
AFTERNOON SHOWERS EAST OF DILLINGHAM. WELL ABOVE NORMAL
TEMPERATURES...15 DEGREES F IN PLACES WILL CONTINUE WITH GENERALLY
LIGHT WINDS.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
A WEAKENING FRONT STRETCHES OVER THE SOUTHERN BERING...UNALASKA
ISLAND...AND ALASKA PENINSULA. THIS FRONT WILL WEAKEN AND MOVE
EASTWARD CONTINUING SNOW AND RAIN FOR THOSE AREAS AS WELL AS THE
PRIBILOF ISLANDS. AS THE FRONT DISSIPATES THE REMAINING
PRECIPITATION WILL BE SHOWERY AS THE LOW CENTER MOVES EASTWARD.
SHOWER COVERAGE WILL LESSEN EACH DAY THROUGH FRIDAY. A NEW FRONT
ENTERS THE WESTERN ALEUTIAN ON FRIDAY AFTERNOON BRINGING ANOTHER
ROUND OF RAIN...SNOW...AND WIND.

&&

.FIRE WEATHER...
THERE ARE NO SIGNIFICANT FIRE WEATHER CONCERNS OVER THE NEXT
COUPLE OF DAYS.

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

A TROUGH CENTERED OVER THE NORTH PACIFIC AND EXTENDING INTO THE
GULF OF ALASKA AND RIDGING OVER THE BERING SEA WILL BE THE MAIN
FEATURES OF INTEREST BEGINNING THE EXTENDED PERIOD ON FRIDAY
AFTERNOON. WEAK WAVES EMBEDDED WITHIN THE FLOW WILL HELP TO SPREAD
MOISTURE...CLOUDS...AND SHOWERS ACROSS THE GULF AND INTO INLAND
LOCATIONS...ALTHOUGH THOSE WILL MOSTLY BE OVER THE MOUNTAINS.
OTHERWISE...WITH A PRESSURE GRADIENT REMAINING CROSS
BARRIER...TEMPERATURES WILL REMAIN WELL ABOVE AVERAGE FOR MOST
INLAND LOCATIONS AS BREAKUP SEASON BEGINS. A STRONG GALE FORCE
FRONT ASSOCIATED WITH ANOTHER LARGE WESTERN BERING LOW WILL MOVE
INTO THE BERING SEA AND TRACK EAST...WITH MORE SOUTHEASTERLY FLOW
ALOFT REDEVELOPING OVER SOUTHERN ALASKA SOMETIME MIDWEEK THROUGH
LATE NEXT WEEK.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.

&&

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