488
FXAK67 PAJK 100530
AFDAJK
SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
930 PM AKDT SUN AUG 9 2026
AVIATION...06Z TAFS
PRIMARILY VFR CONDITIONS CONTINUE AT THIS
TIME WITH LOCAL SEA BREEZES QUICKLY COMING TO AN END. A FEW RAIN
SHOWERS DEVELOPED NEAR MOSQUITO LAKE AND SKAGWAY EARLIER THIS
EVENING, BUT THE MOST ORGANIZED CONVECTION AND LIGHTNING REMAINED
JUST OUTSIDE THE VICINITY. A FEW ADDITIONAL SHOWERS CANNOT BE
RULED OUT IN THESE AREAS OVER THE NEXT FEW HOURS. AS SURFACE HIGH
PRESSURE REMAINS OVER THE CENTRAL GULF, ALONG WITH AN UPPER LEVEL
LOW, WE EXPECT A LOWERING OF CEILINGS TO MVFR. ALTHOUGH, SOME MID
AND HIGH LEVEL CLOUDS ACROSS THE NORTHERN AND CENTRAL PANHANDLE
MAY REDUCE OR SLOW THE FORMATION OF LOW CLOUDS OVERNIGHT. POCKETS
OF IFR WILL BE ASSOCIATED WITH THE MARINE LAYER ALONG THE OUTER
COAST SITES AND PAKW. CONDITIONS WILL AGAIN SLOWLY IMPROVE ACROSS
THE REGION BEGINNING AROUND 18Z.
PREV DISCUSSION...ISSUED AT 241 PM AKDT SUN AUG 9 2026
SYNOPSIS...
KEY MESSAGES:
-SUICIDE BASIN GLACIER DAMMED LAKE CONTINUES TO FILL. AT THIS
TIME, IT IS EXPECTED TO BE FULL SOMETIME AUGUST 11TH OR 12TH. IN
THE PAST, IT HAS TAKEN UP TO 6 DAYS FOR THE MAIN FLOODING EVENT
TO START AFTER THE BASIN IS FULL. VISIT
WEATHER.GOV/AJK/SUICIDEBASIN FOR MORE INFORMATION.
-SOME AREAS OF CLOUDS AND A GRADUAL WARMING TREND EXPECTED THROUGH
THE WEEK FOR THE PANHANDLE.
SHORT TERM...RELATIVELY QUIET WEATHER CONTINUES. GENERAL FLOW AT
MID AND UPPER LEVELS HAS TURNED TO A MOSTLY OFFSHORE N TO NE
DIRECTION WHILE LOW LEVEL FLOW IS MORE NW OR W. AS A RESULT MOST
OF THE PANHANDLE IS SEEING MORE AND LARGER HOLES IN THE CLOUD
COVER THIS AFTERNOON. THE MOST CLOUD COVER IS STILL OVER THE
JUNEAU AND ICY STRAIT AREA WHERE SOME MID LEVEL CONVERGENCE IS
KEEPING MID LEVEL CLOUDS AROUND.
THROUGH THE EARLY PART OF THE WEEK, AREAS OF CLOUDS WILL STICK
AROUND BUT SUBSTANTIAL HOLES IN THAT CLOUD COVER WILL STILL
DEVELOP DUE TO OVERALL LIGHT OFFSHORE FLOW. SOME MARINE LAYER LOW
CLOUDS WILL ALSO PLAGUE THE OUTER COAST LATE AT NIGHT AND IN THE
MORNINGS WITH SOME POSSIBLE FOG AT TIMES. THE LIGHT OFFSHORE FLOW
WILL ALSO CONTINUE TO BRING IN A SLIGHTLY WARMER AIR MASS. 850 MB
TEMPERATURES WILL BE SLIGHTLY WARMING THROUGH THE NEXT FEW DAYS
FROM AROUND 6C TODAY TO AROUND 8C BY TUESDAY. THIS WILL RESULT IN
AFTERNOON HIGH TEMPERATURES SHOWING A GRADUAL WARMING TREND WITH
UPPER 60S AND LOW 70S STARTING TO BECOME MORE COMMON BY TUESDAY
ESPECIALLY IN AREAS THAT SEE MORE SUN. SEA BREEZES WILL ALSO
INCREASE WITH THE INCREASED AFTERNOON HEATING. WINDS ARE LIKELY
TO TOP OUT AT AROUND 15 TO 20 KT AT MOST IN THE AFTERNOONS AND
EVENING.
ONE OF THE OTHER QUESTION MARKS IS THE POTENTIAL FOR ANY SHOWERS
OR THUNDERSTORMS TO MOVE INTO THE NORTHERN PANHANDLE FROM CANADA
THIS EVENING AND MONDAY AFTERNOON. SATELLITE IMAGERY AND LIGHTNING
DETECTION TODAY HAVE SHOWN A FEW STORMS DEVELOPING IN THE SOUTHERN
YUKON AS OF 1PM. NOTHING HAS COME CLOSE TO THE HAINES CUSTOMS OR
WHITE PASS AREA YET, BUT THE STEERING FLOW IS STILL OUT OF THE
NORTH SO WILL DIRECT ANY STORMS IN THE SOUTHERN YUKON TO THE
SOUTH. HIGHER POPS AND A SLIGHT CHANCE OF THUNDERSTORMS REMAIN IN
THE FORECAST AROUND WHITE PASS AND HAINES CUSTOMS FOR THIS EVENING
AND MONDAY AFTERNOON AS CONVECTIVE INDICES REMAIN GOOD FOR BOTH
TIME PERIODS.
LONG TERM...WEDNESDAY, A CLOSED LOW SOUTH OF THE ALEUTIAN CHAIN
WILL REACH FULL MATURITY, BEGINNING TO DECAY AS IT LIFTS NORTH.
THREE PRIMARY FEATURES OF INTEREST AS THIS SYSTEM MOVES INTO THE
GULF ARE: STRENGTH OF THE ACCOMPANYING SURFACE LOW, CLEAR/WARM
OVER THE PANHANDLE FOR THE MID TO END OF THE WEEK, AND MOISTURE
TRANSPORT INTO THE REGION BY THE WEEKEND. TOUCHING ON THE LOW
FIRST, ENSEMBLES SHOW AGREEMENT THAT THIS SYSTEM WILL MAKE
LANDFALL ALONG THE AK PENINSULA, WITH SOUTHERLIES BUILDING IN THE
CENTRAL GULF; WINDS REMAIN BELOW GALE FORCE. OUR STUBBORN HIGH
OVER THE EASTERN GULF CEDES TERRITORY, MAKING A SLIGHT RETREAT
INTO THE PANHANDLE, WITH NORTH-WESTERLIES STILL IMPACTING MUCH OF
THE COASTAL WATERS. OVERALL, LITTLE CONCERN FOR MAJOR MARINE
IMPACTS WITH CONTINUED FOCUS FOR NORTHWEST WINDS OF MODERATE TO
FRESH BREEZES ALONG THE ALEXANDER ARCHIPELAGO AND SEA BREEZES THRU
THE INSIDE.
AS THIS HIGH SHIFTS INTO THE PANHANDLE THURSDAY, WARM AND DRY
ONCE AGAIN BECOMES THE THEME. DIGGING INTO THE 850MB TEMPS, THE
LREF SHOWS A LEFT-SKEWED DISTRIBUTION BASED AROUND 7C TO 15C, WITH
THE MODE AROUND 13C, TRANSLATING TO 75F TO 85F SURFACE TEMPS,
ABOUT 10F ABOVE NORMAL FOR THIS TIME OF YEAR. THE EXTREME FORECAST
INDEX SHINES MORE LIGHT INTO THIS, WITH AGREEMENT IN ABNORMAL
WARMTH INCREASING ITS FOOTPRINT OVER THE PANHANDLE INTO THE END OF
THIS WEEK. A NOTE, IT’S NOT JUST ABOUT THE AFTERNOON HIGH
TEMPERATURES, NIGHTLY LOW TEMPERATURES ALSO LIKELY REMAIN ABOUT
10F ABOVE NORMAL FOR MOST OF THE REGION.
MOVING ONTO MOISTURE, BY THE END OF THE WEEKEND THIS PATTERN WILL
BEGIN TO BREAK DOWN THE DOMINANT HIGH, OR AT A MINIMUM, PUSH THE
RIDGE FURTHER EAST, WITH SOUTHWESTERLIES PICKING UP ON SOME
EQUATORIAL MOISTURE AND FUNNELING IT INTO THE GULF. A FEW ENSEMBLE
OUTLIERS WANT TO BRING A QUICK HIT OF MODERATE AR CONDITIONS;
HOWEVER, OVERALL MODEST INTEGRATED VAPOR TRANSPORT VALUES SUGGEST
JUST AN INCREASE IN CLOUDS, AND PERHAPS SOME LIGHT RAIN, BY THE
END OF THE WEEKEND.
SIMILAR TO PREVIOUS DAYS, WINDS OF SUSTAINED 10 TO 15 KTS WILL
CONTINUE THROUGH THIS AFTERNOON, WITH THE HIGHEST CHANCE OF SEEING
ANY GUSTS REACHING 20 KTS BEING IN THE VICINITY OF TAIYA INLET.
NO LLWS CONCERNS THROUGH THE TAF PERIOD.
MARINE...
OUTSIDE: A 1023MB HIGH PRESSURE REMAINS STATIONARY OVER THE
CENTRAL GULF INTO EARLY NEXT WEEK, KEEPING GENERALLY OVERCAST
SKIES WITH LIGHT AND VARIABLE WINDS ALONG IN THE OUTER WATERS.
WAVE HEIGHTS REMAIN LARGELY BENIGN THROUGH THE EARLY WEEK, AROUND
4FT OR LESS ALONG THE COAST WITH A PERSISTENT SOUTHERLY SWELL OF
2FT OR LESS. ACCOMPANYING THIS HIGH PRESSURE IS BROAD WESTERLY TO
NORTHWESTERLY WINDS IN THE NE GULF COAST DOWN TO DIXON ENTRANCE
AROUND 10 TO 15 KTS OR LESS, WITH THE STRONGEST WINDS EXPECTED IN
THE VICINITY OF CAPE SPENCER AND CAPE DECISION, PARTICULARLY BY
THE AFTERNOON HOURS. MAIN MARINE CONCERN FOR OUTER AND COASTAL
WATERS WILL BE NIGHTLY RETURN OF MARINE LAYER, DROPPING
VISIBILITIES POTENTIALLY AS LOW AS ONE QUARTER MILE EACH MORNING.
INSIDE: CONDITIONS ACROSS THE INSIDE WATERS REMAIN RELATIVELY
BENIGN THIS AFTERNOON WITH ONLY A FEW AREAS SEEING WINDS ABOVE 10
KT, NAMELY NEAR OCEAN ENTRANCES AS WELL AS LOCALIZED SEA BREEZES.
THIS PATTERN OF RELATIVELY BENIGN CONDITIONS WITH MARINE LAYER
INFLUENCE AND PATCHY FOG IN THE MORNING GIVING WAY TO INCREASING
WINDS AND SEA BREEZES BY THE AFTERNOON WILL HOLD TRUE THROUGH AT
LEAST MIDWEEK. WAVE HEIGHTS REMAIN 4 FEET OR LESS THROUGH EARLY
WEEK AS WELL WITH NO SIGNIFICANT SYSTEMS TO BREAK DOWN THE
INFLUENCE OF HIGH PRESSURE OUT IN THE GULF.
HYDROLOGY...SUICIDE BASIN CONTINUES TO FILL. WITH THE CLOUDY AND
SOMEWHAT COOL WEATHER WE HAVE HAD OVER THE WEEKEND AS WELL AS THE
CALVING EVENT ON FRIDAY NIGHT, WE HAVE MOVED THE EXPECTED MOST
LIKELY DATE FOR A FULL BASIN TO BE AUGUST 11TH-12TH. THE OVERFLOW
CHANNEL IS STILL AROUND 1350 FT AND WE STILL EXPECT THE RELEASE TO
START UP TO 6 DAYS AFTER THE BASIN HAS REACHED FULL STATUS.
AJK WATCHES/WARNINGS/ADVISORIES
PUBLIC...NONE.
MARINE...NONE.
SHORT TERM...EAL
LONG TERM...AP
AVIATION...MJB/STJ
MARINE...STJ
HYDROLOGY...EAL
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