986
FXAK68 PAFC 220052
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
452 PM AKDT SUN JUN 21 2026
SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3)
CURRENTLY, A NORTH PACIFIC LOW IS MOVING INTO THE GULF OF ALASKA.
THIS LOW IS PUSHING MOISTURE UP INTO SOUTHCENTRAL, LEADING TO
SCATTERED SHOWERS ALONG THE COAST AND INTO THE KENAI PENINSULA.
MEANWHILE, ISOLATED SHOWERS AND THUNDERSTORMS ARE FORMING IN THE
TALKEETNA MOUNTAINS AND THE COPPER RIVER BASIN AS INSTABILITY
REMAINS ELEVATED. SHORTWAVES FROM THE LOW ARE CREATING A COASTAL
RIDGE OVER THE CHUGACH RANGE. THIS WILL ALLOW FOR ELEVATED
SOUTHEASTERLY WINDS (10 TO 15 MPH) IN PALMER, SOUTH ANCHORAGE,
AND THE COPPER RIVER BASIN TODAY THROUGH MONDAY. MONDAY WILL BE
SIMILAR TO TODAY EXCEPT WITH INCREASED SHOWER ACTIVITY AS THE LOW
MOVES FURTHER INTO THE GULF AND ADDITIONAL SHORTWAVES PUSH INTO
SOUTHCENTRAL. THE ANCHORAGE AREA WILL BE DOWNSLOPED DUE TO
EASTERLY FLOW, BUT LIGHT RAIN SHOWERS WILL STILL HAVE A 20 TO 30%
CHANCE OF OCCURRING.
BY TUESDAY, A STRONG SHORTWAVE FROM THE LOW WILL MOVE ACROSS
SOUTHCENTRAL FROM THE EAST. THIS WAVE WILL PRODUCE A DEFORMATION
BAND, WHICH WILL CAUSE MODERATE TO HEAVY RAIN FIRST IN HIGHER
ELEVATIONS OF THE ALASKA RANGE AND THE TALKEETNA MOUNTAINS. LOWER
ELEVATION AREAS INCLUDING ANCHORAGE WILL SEE LESS RAINFALL DUE TO
DOWNSLOPING, BUT THE SHEER AMOUNT OF MOISTURE MAKING IT IN WILL
ALLOW AT LEAST 0.05 TO 0.10 INCHES OF RAIN TO FALL. BY TUESDAY
AFTERNOON, THE BAND OF MODERATE TO HEAVY RAINFALL WILL MOVE OVER
THE NORTHERN AND WESTERN SUSITNA VALLEY INCLUDING TALKEETNA AND
SKWENTNA, WHERE IT WILL LINGER THROUGH WEDNESDAY. BETWEEN TUESDAY
AND WEDNESDAY, BETWEEN 1 AND 3 INCHES OF RAINFALL WILL FALL
DEPENDING ON WHERE THE BAND OF RAIN SETS UP. THERE IS UNCERTAINTY
WITH THIS EVENT AND IF THE RAIN BAND SETS UP FURTHER WEST, THE
LOWER AMOUNTS OF RAINFALL WILL BE SEEN. CONVERSELY, IF THE RAIN
BAND SETS UP FURTHER EAST, THE HIGHER END OF THE RANGE WILL BE
MORE LIKELY. BY WEDNESDAY EVENING, RAINFALL WILL DECREASE IN
INTENSITY AS THE LOW MOVES MORE TO THE EAST AND THE STRONG
SHORTWAVE INLAND DISSIPATES. ADDITIONAL SHORTWAVES WILL MOVE
THROUGH, BUT THESE WILL NOT BE NEARLY AS STRONG AND RAINFALL
ASSOCIATED WITH THEM WILL BE LIGHTER.
-JAR
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (DAYS
1 THROUGH 3: TODAY THROUGH WEDNESDAY AFTERNOON)...
GENERALLY A TREND TOWARDS MORE UNSETTLED AND ACTIVE WEATHER AS
LOWS PROGRESS INTO THE REGION AND THE RIDGE OVER THE BERING SEA
WEAKENS AND GETS DISPLACED. ISOLATED THUNDERSTORMS WILL LIKELY
KEEP A FOOTHOLD ACROSS THE KUSKOKWIM RIVER AND DELTA AND ALONG THE
ALASKA RANGE, THOUGH ACTIVITY WILL LIKELY BE LESS WIDESPREAD AS WE
HEAD INTO THE WORK WEEK. FOR THE BERING SEA AND ALEUTIAN ISLANDS,
FOG AND LOW CLOUDS WILL GRADUALLY GIVE WAY TO BRISK WINDS AND
STEADY RAIN AS LOWS MOVE IN FROM THE NORTH PACIFIC.
DIVING INTO THE DETAILS... AN UPPER LOW NEAR THE WESTERN TIP OF
THE ALEUTIANS AND A LOW COMPLEX MOVING ACROSS THE ALASKA PENINSULA
INTO THE GULF WILL BE THE PRIMARY WEATHER INFLUENCES OVER THE NEXT
FEW DAYS. THE PRIMARY FORECAST CHALLENGE REMAINS THUNDERSTORM
POTENTIAL ALONG THE KUSKOKWIM RIVER CORRIDOR. SURFACE HEATING AND
INSTABILITY WILL LIKELY CONTINUE TO TREND LOWER AS THE ALASKA
PENINSULA LOW BRINGS INCREASING CLOUD COVER INTO THE REGION.
HOWEVER, AS SEEN YESTERDAY AND TODAY, MORNING CLOUD COVER MAY BURN
OFF JUST ENOUGH FOR ROBUST SHOWERS AND THUNDERSTORMS TO FIRE OFF.
THE MAIN ISSUE WITH THE THUNDERSTORM FORECAST WILL BE HONING IN ON
THE UPPER LEVEL SHORTWAVES ROTATING AROUND THE UPPER LOW, WHICH
WILL PROVIDE THE LIFT NEEDED FOR THESE THUNDERSTORMS. MODELS ARE
SHOWING SOME TIMING DIFFERENCES WITH THESE FEATURES, AND
THUNDERSTORM POTENTIAL WILL LIKELY DEPEND ON WHERE THESE WAVES
COINCIDE WITH POCKETS OF CLEARER SKY AND WARMER SURFACE
TEMPERATURES. THOUGH CONFIDENCE IS LOWER IN THE EXACT LOCATION OF
THUNDERSTORMS, CONFIDENCE IS HIGHER THAT THESE STORMS WILL
GENERALLY REMAIN ALONG THE KUSKOKWIM RIVER CORRIDOR AND OUT OF THE
POPULATED AREAS OF BRISTOL BAY.
-KC
.LONG TERM FORECAST (DAYS 4 THROUGH 7: THURSDAY THROUGH
SUNDAY)...
AN UNSETTLED PATTERN IS EXPECTED TO PERSIST ACROSS SOUTHCENTRAL
ALASKA AND THE ALEUTIANS THROUGH THE END OF THE WEEK INTO THE
WEEKEND. A BROAD UPPER TROUGH AND SURFACE LOW PRESSURE OVER THE
GULF OF ALASKA WILL MAINTAIN EXTENSIVE CLOUD COVER AND PERIODIC
SHOWERS ACROSS SOUTHCENTRAL. THE GREATEST PRECIPITATION CHANCES
WILL REMAIN ALONG THE COASTAL MOUNTAINS AND WINDWARD TERRAIN,
THOUGH SCATTERED INLAND SHOWERS ARE ALSO EXPECTED DURING THE
AFTERNOON AND EVENING HOURS. TEMPERATURES SHOULD REMAIN NEAR TO
SLIGHTLY BELOW SEASONAL NORMALS UNDER THE PERSISTENT CLOUD COVER.
FARTHER WEST, A BERING SEA LOW WILL GRADUALLY TRACK EASTWARD
TOWARD THE ALEUTIANS, BRINGING PERIODS OF RAIN AND LOCALLY GUSTY
WINDS TO THE ISLAND CHAIN THROUGH LATE WEEK. AS THE SYSTEM MOVES
INTO THE WESTERN MAINLAND, IT WILL BECOME ABSORBED INTO A MORE
ZONAL WESTERLY FLOW ALOFT, ALLOWING PRECIPITATION CHANCES TO
SPREAD EASTWARD WHILE KEEPING GENERALLY UNSETTLED CONDITIONS IN
PLACE THROUGH SUNDAY.
MEANWHILE, A RIDGE CENTERED OVER THE CENTRAL BERING WILL PROMOTE
COMPARATIVELY QUIETER WEATHER ACROSS THE ALASKA PENINSULA AND
PORTIONS OF SOUTHWEST ALASKA. HOWEVER, DAYTIME HEATING AND WEAK
INSTABILITY MAY STILL SUPPORT ISOLATED AFTERNOON SHOWERS,
PARTICULARLY ALONG THE WESTERN SLOPE OF HIGHER TERRAIN.
FORECAST CONFIDENCE DECREASES TOWARD THE LATTER HALF OF THE PERIOD
AS MODEL SOLUTIONS DIVERGE ON THE EVOLUTION AND PLACEMENT OF THE
BERING LOW AND ASSOCIATED UPPER-LEVEL FEATURES. DESPITE THESE
DIFFERENCES, CONFIDENCE REMAINS MODERATE THAT MUCH OF SOUTHERN
ALASKA WILL STAY COOLER, SHOWERY, AND GENERALLY UNSETTLED PATTERN
THROUGH SUNDAY.
LM
AVIATION
PANC...VFR CONDITIONS ARE EXPECTED TO PERSIST THROUGH THE PERIOD.
A TURNAGAIN ARM WIND WILL DEVELOP THIS AFTERNOON/EVENING AND HAS
A CHANCE OF PRODUCING GUSTS UP TO 20 KTS BEFORE DIMINISHING BY
AROUND 14Z MONDAY MORNING.
FIRE WEATHER
FOR SOUTHCENTRAL ALASKA:
A RED FLAG WARNING REMAINS IN EFFECT FOR SOUTHERN, CENTRAL,
WESTERN AND NORTHERN SUSITNA VALLEY AND THE LOWER MATANUSKA VALLEY
DUE TO LIGHTNING UNTIL 1 AM AKDT SATURDAY.
DISCUSSION: SCATTERED SHOWERS AND WET THUNDERSTORMS HAVE
DEVELOPED THIS AFTERNOON ACROSS THE SUSITNA VALLEY, MAINLY ALONG
THE EASTERN SLOPES OF THE TALKEETNAS AND WEST OF THE TALKEETNAS
WHERE TEMPERATURES HAVE WARMED WELL INTO THE 70S TODAY. STORM
MOTION IS SLOW TODAY AND TO THE NORTHWEST WITH TIME. ALTHOUGH
THESE STORMS ARE PRODUCING LOCALLY HEAVY DOWNPOURS AND COULD DROP
SOME SMALL HAIL, THE PRIMARY CONCERN IS FREQUENT LIGHTNING STRIKES
OUTSIDE OF AREAS THAT SEE RAINFALL FOR POTENTIAL FIRE STARTS.
STORM COVERAGE WILL LIKELY INCREASE AS THE AFTERNOON WEARS ON AND
BEGIN TO DECREASE LATE THIS EVENING AS WE LOSE DAYTIME HEATING AND
ASSOCIATED UPPER LEVEL ENERGY EXITS THE REGION. A FEW REMNANT
SHOWERS COULD LINGER EARLY SATURDAY MORNING. THERE IS MEDIUM TO
HIGH (70-80%) CONFIDENCE THAT THE FOCUS FOR THUNDERSTORM ACTIVITY
SATURDAY AFTERNOON WILL LIKELY SHIFT EASTWARD TO THE COPPER RIVER
BASIN, MEANING LESS STORM COVERAGE ACROSS THE SUSITNA VALLEY AND
LOWER MATANUSKA VALLEY.
FOR SOUTHWEST ALASKA:
A RED FLAG WARNING REMAINS IN EFFECT FOR LIME VILLAGE DUE TO
LIGHTNING UNTIL 1 AM AKDT SATURDAY.
DISCUSSION: THE FORECAST LOOKS ON TRACK REGARDING THE RED FLAG
WARNING IN EFFECT THROUGH TONIGHT. SCATTERED WET THUNDERSTORMS
ARE CURRENTLY DEVELOPING OFF THE FOOTHILLS OF THE WESTERN ALASKA
RANGE IN LIME VILLAGE, WITH THE EXPECTATION THAT 10 TO 15 KT OF
STEERING FLOW WILL LEAD TO NORTHWEST PROPAGATION OF THUNDERSTORMS
THROUGH THE EVENING. GIVEN MODELED CAPE RANGING FROM 300-700 J/KG,
THESE THUNDERSTORMS MAY PRODUCE HAIL AND GUSTY WINDS IN ADDITION
TO FREQUENT LIGHTNING. FOR TOMORROW, HAVE INCREASED THE FOOTPRINT
OF THUNDERSTORMS ACROSS THE KUSKOKWIM RIVER CORRIDOR FROM THE
COAST TO LIME VILLAGE, BUT CONFIDENCE IS LOWER REGARDING WHERE
THERE MAY BE WIDELY SCATTERED OR PERHAPS EVEN SCATTERED
THUNDERSTORMS. WHILE MAX SURFACE-BASED CAPE LOOKS LOWER FOR
TOMORROW, THERE LOOKS TO BE A LARGER FOOTPRINT OF 200-400 J/KG,
WHICH WOULD LIKELY BE SUFFICIENT TO PRODUCE WIDELY SCATTERED
THUNDERSTORMS. HOWEVER, THERE IS POOR MODEL AGREEMENT REGARDING
WHERE THE HIGHEST CAPE WILL BE; AS SUCH, HAVE PUT IN A PRELIMINARY
AREA OF WIDELY-SCATTERED THUNDERSTORMS IN KUSKOKWIM VALLEY EAST
AND LIME VILLAGE WHERE TEMPERATURES WILL LIKELY BE WARMEST AND
SKIES CLEAREST.
-AM/KC
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