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FXAK68 PAFC 291336
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
536 AM AKDT FRI MAY 29 2026
SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3)
THE OVERALL GENERAL PATTERN OF A NEARLY STATIONARY, VERTICALLY
STACKED LOW IS ANCHORED IN THE GULF OF ALASKA. ITS SHORTWAVE
EXTENDING FROM THIS LOW REMAINS NEAR THE YUKON AND IS ROTATING
WESTWARD THROUGH THE COPPER RIVER BASIN. SHOWERS UNDER NORTHERLY
FLOW ARE ON-GOING THIS MORNING ACROSS THE WRANGELL MOUNTAINS,
SOUTHEASTERN COPPER RIVER BASIN, AND THE VALDEZ-CORDOVA AREA.
THE POTENTIAL FOR SHOWERS AND ISOLATED THUNDERSTORMS WILL RETURN
THIS AFTERNOON ALONG WITH SEA BREEZES NEAR THE COAST. A COASTAL
RIDGE WILL DEVELOP TODAY THAT WILL ALLOW FOR SOUTHERLY GAP WINDS
TO DEVELOP THROUGH TURNAGAIN ARM, COPPER RIVER, KNIK RIVER, AND
OTHER SOUTHERLY VALLEY/TERRAIN GAPS.
ALTHOUGH THERE IS MORE CONVECTIVE POTENTIAL TODAY THAN THERE WAS
YESTERDAY, LIMITING FACTORS FOR THUNDERSTORM DEVELOPMENT WOULD BE
FROM INCREASED CLOUD COVER THAT WOULD LIMIT SURFACE HEATING AND
ITS ABILITY TO DESTABILIZE THE ATMOSPHERE OVER THE SOUTHERN TIER
OF SOUTHCENTRAL. SECOND, THE UPPER LEVEL FEATURES ARE QUITE
COMPLEX, WITH A PLETHORA OF SHORTWAVES AND VORTICITY MAXIMA MOVING
THROUGH A SHORT-WAVE RIDGE. CONTINUED NORTHERLY FLOW ACROSS THE
ALASKA RANGE WILL LEAD TO MORE UNSTABLE CONDITIONS OVER INTERIOR
SOUTHCENTRAL, ESPECIALLY ACROSS THE NORTHERN SUSITNA VALLEY AND
TALKEETNA MOUNTAINS. THE COMPLEXITY OF THE SET-UP MAKES IT
DIFFICULT TO PINPOINT AREAS OF CONVECTIVE INITIATION. BASED ON
OVERALL LEVEL OF INSTABILITY (AND TAKING INTO ACCOUNT CLIMATOLOGY
PREFERRED AREAS FOR INITIATION) THE MOST LIKELY AREAS FOR
CONVECTION ARE THE NORTHERN PORTIONS OF THE SUSITNA VALLEY AND
COPPER BASIN AS WELL AS THE TALKEETNA MOUNTAINS SOUTHWARD TO THE
FRONT RANGE CHUGACH NEAR ANCHORAGE. SIMPLE ADVECTION COULD CAUSE
SOME OF THESE TO MOVE OVER POPULATED AREAS OF THE MATANUSKA VALLEY
AND ANCHORAGE. THUNDERSTORM POTENTIAL IS HIGHER OVER THE INTERIOR
THEN SOUTHWARD ACROSS THE TALKEETNA MOUNTAINS TO THE MAT VALLEY.
AS WE HEAD TO THE WEEKEND, THE WEAK UPPER LEVEL SHORTWAVE RIDGE
WILL SIT OVERHEAD WHILE A WEAK SHORTWAVE DROPS SOUTHWARD FROM THE
INTERIOR AND STALLS ALONG/NEAR THE ALASKA RANGE. IT'S LOOKING
INCREASINGLY LIKELY THAT MOISTURE WILL BE TRAPPED BENEATH THE
RIDGE AND LEAD TO MOSTLY CLOUDY SKIES OVER THE WEEKEND (WITH JUST
AN OCCASIONAL BREAK OF SUN). A LOSS OF NORTHERLY FLOW WILL LEAD TO
A SLIGHT COOLING OF THE AIRMASS AND MORE STABLE CONDITIONS. THIS
WILL LEAD TO LOWER COVERAGE OF SHOWERS AND GENERALLY LIGHTER
RAINFALL WITHIN ANY SHOWERS. INCREASING SOUTHERLY FLOW UP COOK
INLET WILL KEEP THE POPULATION CENTERS DRY (OR MOSTLY DRY). THE
CLOUD COVER AND COOLISH AIRMASS MEANS TEMPERATURES WILL MAX OUT IN
THE 50S FOR MOST AREAS.
LASTLY, IT IS WORTH HIGHLIGHTING THAT MUCH WARMER AND SUNNIER
WEATHER REMAINS ON TRACK FOR NEXT WEEK.
-SEB/RUX
.SHORT TERM FORECAST SOUTHWEST ALASKA, THE BERING SEA/ALEUTIANS
(DAYS 1 THROUGH 3)...
AS OF THIS MORNING, MOST OF SOUTHWEST ALASKA HAS BEEN LOCKED IN
WITH LOW STRATUS, AREAS OF MIST, AND FOG. SURFACE ANALYSIS SHOWS A
SUBTLE RIDGE AXIS DRAPED ALONG THE ALASKA PENINSULA INTO
SOUTHWEST ALASKA, WHICH HAS SET UP A LOW-LEVEL INVERSION THAT HAS
TRAPPED IN INCOMING MOISTURE/CLOUD COVER RIDING UNDER THE
INVERSION FROM THE NORTHEAST FROM SCATTERING OUT OF THE AREA. THE
CONSENSUS FROM THE GUIDANCE THAT HAS INITIALIZED LOW CEILINGS AND
VISIBILITY KEEPS AREAS OF FOG IN THE REGION THROUGH 18Z OR SO THIS
MORNING.
ELSEWHERE, FAIRLY WEAK UPPER LEVEL WAVES MOVING SOUTHWARD FROM
THE NORTHERN BERING SEA HAVE HELPED TO DRIVE A WEAK AREA OF LOW
PRESSURE AND SURFACE TROUGH SOUTHEASTWARD ACROSS THE SOUTHERN
BERING AND TOWARD THE CENTRAL/EASTERN ALEUTIANS. MODEL GUIDANCE
INDICATES THAT SURFACE HIGH PRESSURE BUILDS ACROSS THE BERING IN
THE WAKE OF THIS LOW PRESSURE SYSTEM THROUGH THIS AFTERNOON,
SUPPRESSING THE OVERALL STORM TRACK TO THE SOUTH FOR MUCH OF THE
SHORT TERM.
MEANWHILE, 500 MB EASTERLY WAVES ROUNDING THE TOP OF A LARGE
UPPER LEVEL LOW OVER THE GULF WILL MOVE OVER SOUTHWEST ALASKA
TODAY AND TOMORROW. WITH ADDED DAYTIME HEATING AND STEEP MID-LEVEL
LAPSE RATES, ISOLATED TO WIDELY SCATTERED SHOWER AND THUNDERSTORM
ACTIVITY FOR THIS AFTERNOON IS EXPECTED, PARTICULARLY FAVORING
THE AREAS FROM CROOKED CREEK TO LIME VILLAGE. SATURDAY AFTERNOON
LOOKS VERY SIMILAR TO FRIDAY AFTERNOON PATTERN-WISE, SO PREPARE
FOR AT LEAST ANOTHER DAY OF MORE DIURNALLY DRIVEN ISOLATED TO
WIDELY SCATTERED THUNDERSTORMS WITH A FEW LIGHTNING STRIKES ACROSS
THE KUSKOKWIM VALLEY.
LOOKING BACK OVER THE BERING, THE AFOREMENTIONED RIDGE OF HIGH
PRESSURE NUDGES EASTWARD SUNDAY, WHICH ALLOWS FOR A HIGH END SMALL
CRAFT KAMCHATKA FRONT TO MOVE TOWARDS THE WESTERN ALEUTIANS. WITH
HIGH PRESSURE STILL IN CONTROL ACROSS THE BERING, THIS FRONT WILL
BECOME BLOCKED FROM PROGRESSING EASTWARD AND STALL OUT AND WEAKEN
THROUGH MONDAY.
LASTLY, MODELS ARE INDICATING THAT A STRONGER FRONT FROM A LOW
PRESSURE SYSTEM LIFTS NORTHWARD FROM THE NORTH PACIFIC HEADING
INTO THE MONDAY TO TUESDAY TIMEFRAME. THERE ARE SOME NOTABLE
DIFFERENCES AMONG THE GLOBAL MODELS, BUT THEY ARE GENERALLY IN
AGREEMENT OF A FRONT COMING CLOSE TO, IF NOT CROSSING THE ALASKA
PENINSULA EARLY NEXT WEEK WITH RAIN AND GUSTY WINDS.
-AM
LONG TERM FORECAST (DAYS 4 THROUGH 7: SUNDAY THROUGH WEDNESDAY)
A HIGH PRESSURE RIDGE WILL DOMINATE ACROSS THE BERING SEA AND
EXTEND INTO THE WESTERN MAINLAND ALASKA WEDNESDAY THROUGH
SATURDAY, KEEPING CONDITIONS GENERALLY STABLE AND DRY OVER WESTERN
ALASKA, THE ALEUTIAN ISLANDS AND THE BERING SEA. MARINE ACTIVITY
SHOULD REMAIN FAIRLY QUIET UNDER THIS SETUP, WITH LITTLE CHANCE OF
WIDESPREAD PRECIPITATION OR SIGNIFICANT WEATHER IMPACTS IN THOSE
FAR WESTERN ZONES.
MEANWHILE, A BROAD UPPER LEVEL LOW WILL STAY ANCHORED WELL SOUTH
OVER THE SOUTHERN GULF OF ALASKA, LIMITING ANY DEEP MOISTURE REACH
INTO SOUTHCENTRAL COASTAL AREAS. EXPECT ONLY LIGHT OR ISOLATED
SHOWERS AT TIMES RATHER THAN HEAVIER OR ORGANIZED RAINFALL ALONG
THE SOUTHCENTRAL COAST FROM THE ALASKA PENINSULA THROUGH THE KENAI
PENINSULA AND PRINCE WILLIAM SOUND REGION. OVERALL THE PATTERN
POINTS TO A RELATIVELY QUIET STRETCH OF WEATHER ACROSS
SOUTHCENTRAL AND WESTERN ALASKA, WITH NO MAJOR PRECIPITATION
EVENTS OR HAZARDS HIGHLIGHTED THROUGH THE WEEKEND.
-DD
AVIATION
PANC...VFR EXPECTED. SOUTHEASTERLY TURNAGAIN ARM WINDS WILL
RETURN BY LATE THIS AFTERNOON LASTING THROUGH TONIGHT WITH GUSTS
UP TO 25 KT. A CHANCE FOR SHOWERS WILL ALSO BE POSSIBLE THIS
AFTERNOON. LOW CONFIDENCE THAT A CEILING BETWEEN 3,500 AND 5,000
FT COULD DEVELOP SATURDAY MORNING AS LOW-LEVEL MOISTURE REMAINS
AND THE ATMOSPHERE STABILIZES.
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