Small Craft Advisory 605, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
440 AM AKDT SUN AUG 2 2015

.ANALYSIS AND UPPER LEVELS...
UPPER LEVEL RIDGING CONTINUES TO BUILD OVER THE BERING...HOWEVER
IT IS BUILDING MORE TO THE NORTH INTO EASTERN RUSSIA THAN TO THE
EAST TOWARD THE MAINLAND. THIS HAS ALLOWED FOR A FIRST IN A SERIES
OF DISTURBANCES MOVING AROUND THE UPPER RIDGE TO DROP SOUTH
ACROSS THE MAINLAND INTO THE SOUTHERN PART OF THE STATE
OVERNIGHT...WHICH WAS LARGELY UNEXPECTED FROM YESTERDAY'S
FORECAST. ISOLATED SHOWERS OVER THE SOUTHERN MAINLAND...WITH
AREAS OF RAIN TOWARD EASTERN PRINCE WILLIAM SOUND AND THE COPPER
RIVER BASIN...WILL CONTINUE TO MOVE SOUTH AND OFFSHORE THIS
MORNING.

THE OTHER FEATURE OF NOTE IS A DEVELOPING LOW PRESSURE SYSTEM
DEVELOPING APPROXIMATELY 300 NM SOUTH OF THE SOUTHERN ALASKA
PENINSULA CURRENTLY. THIS LOW WILL STRENGTHEN RAPIDLY THIS MORNING
INTO EARLY AFTERNOON...THEN MAINTAIN STRENGTH WHILE DRIFTING NORTH
THROUGH MONDAY.

&&

.MODEL DISCUSSION...
MODELS CONTINUE TO DO WELL WITH THE SYNOPTIC PATTERN THROUGH THE
FIRST HALF OF NEXT WEEK WITH THE EXCEPTION OF THE DISTURBANCES
MOVING SOUTH ACROSS THE MAINLAND INTO THE ANCHORAGE AREA OF
RESPONSIBILITY OVERNIGHT. THIS HAS RESULTED IN CHANGES TO THE
FORECAST OVERNIGHT INTO THIS MORNING...BUT WITH THE SECOND
DISTURBANCE EXPECTED TO REMAIN DRY WITH JUST HIGH CLOUDS...EXPECT
NOT AS DRAMATIC CHANGE TO THE FORECAST FOR TODAY INTO TONIGHT.

MODELS CONTINUE TO BE FAIRLY CONSISTENT WITH HANDLING OF THE
DEVELOPING LOW PRESSURE SYSTEM SOUTH OF THE AKPEN...WITH IT
DRIFTING NORTH AND THEN EVENTUALLY EAST THROUGH THE FAR SOUTHERN
GULF TOWARD THE MIDDLE TO LATE PART OF THE WEEK. THIS IS A
SLIGHTLY GROWING SPREAD IN PLACEMENT AND TIMING OF THIS FEATURE BETWEEN
THE MODELS...BUT OVERALL THESE DIFFERENCES ARE NOT VERY
SIGNIFICANT.

&&

.FIRE WEATHER...
INCREASED CLOUD COVER TODAY IN THE MIDDLE AND UPPER LEVELS WILL
HELP KEEP HUMIDITY LEVELS HIGHER THAN PREVIOUSLY FORECASTED FOR
MOST LOCATIONS. OTHERWISE...NO MAJOR CHANGES FROM PREVIOUS
THINKING AS WARMER AND DRIER CONDITIONS ARE STILL EXPECTED IN
SOUTHERN ALASKA FOR THE FIRST HALF OF THIS WEEK DUE TO THE UPPER
LEVEL HIGH BUILDING OVER THE AREA. WINDS WILL LIKELY REMAIN FAIRLY
LIGHT AND RELATIVE HUMIDITY VALUES ARE NOT LIKELY TO DROP BELOW 30
PERCENT.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
HIGH PRESSURE WILL BUILD OVER SOUTH CENTRAL ALASKA TODAY AND
MONDAY. A WEAK UPPER LEVEL SYSTEM EXITING THE AREA TODAY WILL
BRING A FEW SHOWERS MAINLY TO THE COPPER RIVER BASIN AND TALKEETNA
MOUNTAINS. OTHERWISE DRY CONDITIONS ARE EXPECTED. CLOUD COVER AND
TEMPERATURES ARE THE MAIN FORECAST CHALLENGES. THE MODELS SHOW
THINGS DRYING OUT CONSIDERABLY AND BECOMING CLEAR DURING THE DAY
TODAY. A LOOK AT THE SATELLITE IMAGES SHOWS A DECENT AMOUNT OF
HIGH CLOUDS UPSTREAM...THUS THE FORECAST CLEARING WAS SLOWED A BIT
COMPARED TO THE MODELS AND PREVIOUS FORECAST. TEMPERATURES LOOK TO
BE SIMILAR TODAY COMPARED TO YESTERDAY...THOUGH THE CLOUDS MAY
CHOP OFF A DEGREE OR TWO. CLOUDS MAY BE SLOW TO CLEAR IN COASTAL
PORTIONS OF THE EASTERN KENAI PENINSULA AND THIS COULD AFFECT
TEMPERATURES AS WELL. MONDAY SHOULD BE DRY...SUNNY...AND WARMER
THAN SUNDAY.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
STABLE CONDITIONS CAUSED BY A STRENGTHENING RIDGE OVER THE BERING
SEA WILL LIMIT SHOWER DEVELOPMENT ACROSS SOUTHWEST ALASKA THROUGH
TUESDAY NIGHT. THE ONE EXCEPTION WILL BE RAIN DEVELOPING OVER THE
ALASKA PENINSULA TUESDAY MORNING...AS A FRONT ASSOCIATED WITH A
NORTH PACIFIC LOW TRACKS FURTHER NORTHEAST OVER THE AREA. WITH A
STABLE ATMOSPHERE IN PLACE OVER THE AREA AND AN ABUNDANCE OF LOW
LEVEL MOISTURE BEING RESUPPLIED BY CONSISTENT ONSHORE FLOW OFF
THE BERING...FOG WILL LIKELY DEVELOP OVER THE KUSKOKWIM DELTA AND
ALASKA PENINSULA THROUGH THE MORNING. THE NEXT SEVERAL NIGHTS
WILL LIKELY SEE FOG ADVECT INLAND....MAINLY OVER THE KUSKOKWIM
DELTA COAST...WHICH WILL BURN OFF EACH DAY AS DAYTIME HEATING
INCREASES.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
FOG AND STRATUS WILL BE A DOMINANT FEATURE OVER THE BERING SEA
AND ALEUTIANS THROUGH TUESDAY...AS A STRONG AREA OF HIGH PRESSURE
SITS OVER THE BERING. THIS HIGH PRESSURE WILL SLOWLY DRIFT
WESTWARD AND WEAKEN..AS A NORTH PACIFIC LOW BEGINS TO TRACK
TOWARDS THE ALASKA PENINSULA MONDAY MORNING. THIS SYSTEM WILL
BRING RAIN AND GUSTY WINDS TO THE ALASKA PENINSULA AND THE
EASTERN ALEUTIANS LATE TONIGHT THROUGH TUESDAY.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
GENERALLY SUNNY SKIES AND SEASONABLY WARM TEMPERATURES WILL
REMAIN OVER THE REGION THROUGH THE MIDDLE OF NEXT WEEK AS HIGH
PRESSURE CONTINUES TO DOMINATE THE BERING SEA AND EXTENDS EASTWARD
OVER THE MAINLAND. MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT
WITH RESPECT TO THE CUTOFF LOW WHICH WILL FORM SOUTH OF THE ALASKA
PENINSULA AND REMAIN IN THAT GENERAL VICINITY THROUGH WEDNESDAY
BEFORE PASSING SOUTH OF THE GULF LATER IN THE WEEK. THE WILL KEEP
ANY ASSOCIATED PRECIPITATION MAINLY CONFINED TO THE AKPEN AND
KODIAK ISLAND. THE CHANCE FOR PRECIPITATION WILL THEN BEGIN TO
INCREASE OVER THE SOUTHERN MAINLAND LATER IN THE WEEK AS HIGH
PRESSURE WEAKENS AND AN UPPER TROUGH DROPS OVER THE NORTHERN HALF
OF ALASKA.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALES...172
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...CC
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...TP
LONG TERM...CB