752
FXAK68 PAFC 130028
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
428 PM AKDT TUE AUG 12 2025
SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3)
A RIDGE OF HIGH PRESSURE OVER SOUTHCENTRAL ALASKA TO CONTINUE
SHIFTING EASTWARD TONIGHT, ALLOWING FOR A FRONT INCOMING FROM
SOUTHWEST ALASKA TO RETURN TO A COOLER, MORE WET PATTERN. THE
FRONT WILL APPROACH IN THE FORM OF SEVERAL SHORTWAVES, EACH
BRINGING A CHANCE FOR SHOWERS OVER AREAS OF SOUTHCENTRAL BEGINNING
FIRST FOR KODIAK EARLY WEDNESDAY MORNING. BY LATE WEDNESDAY
MORNING, THE FRONT WILL SHIFT OVER THE KENAI PENINSULA, INITIATING
SHOWERS LARGELY ACROSS THE MOUNTAINS, HOMER, AND SEWARD. THE
IMPACT OF THIS FRONT OVER INTERIOR SOUTHCENTRAL HAS BEEN A POINT
OF FOCUS FOR THE FORECAST THE LAST FEW DAYS, HOWEVER CONFIDENCE IS
GROWING TOWARDS A SLIGHTLY DRIER PUSH. AS SUCH, THERE IS A CHANCE
FOR LIGHT RAIN SHOWERS TO DEVELOP FOR ANCHORAGE WEDNESDAY
AFTERNOON AND EVENING, PEAKING WEDNESDAY NIGHT INTO THURSDAY
MORNING, HOWEVER PROLONGED RAINFALL IS NOT EXPECTED FOR THE
ANCHORAGE AREA WITH THIS SYSTEM. THE SUSITNA VALLEY WILL LIKELY
SEE A MORE ORGANIZED PUSH OF RAIN BY THURSDAY MORNING. CHANCES FOR
RAINFALL FROM THIS SYSTEM MAY PERSIST INTO THURSDAY MORNING BEFORE
WEAKENING AND SHIFTING EASTWARD. CHANCES FOR RAIN IN THE COPPER
RIVER BASIN TO INCREASE RELATIVELY BY THURSDAY EVENING HOWEVER
WIDESPREAD SHOWERS ARE NOT EXPECTED.
-CL
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS
(TUESDAY THROUGH THURSDAY)...
THIS AFTERNOON, SATELLITE IMAGERY REVEALS AN AREA OF LOW PRESSURE
NEAR GAMBELL. ITS ATTENDANT FRONT IS SITUATED ALONG THE WESTERN
ALASKA COASTLINE, EXTENDING FROM HOOPER BAY SOUTHWARD TO THE
ALASKA PENINSULA. RADAR SHOWS A SWATH OF RAIN MOVING ACROSS
SOUTHWEST ALASKA AND THE ALASKA PENINSULA. A HIGH SURF ADVISORY IS
IN EFFECT FOR THE KUSKOKWIM DELTA COAST UNTIL 10PM AKDT TONIGHT
FOR WATER LEVELS 1 TO 2 FEET ABOVE THE NORMAL HIGHEST TIDE LINE
AND WAVES UPWARDS OF 4 TO 8 FEET. GAP WINDS ARE STILL PLAGUING THE
EASTERN ALEUTIANS WITH GUSTS UP TO 30-40 KTS THROUGH FAVORABLE
BAYS AND PASSES. THE PERSISTENT ONSHORE FLOW TO THE KUSKOKWIM
DELTA AND GAP WINDS FOR THE EASTERN ALEUTIANS WILL BEGIN TO RELAX
THIS EVENING AS THE FRONT WEAKENS AND STALLS OVER THE AREA. ALOFT,
THERE IS A SHORTWAVE MOVING OVER THE PRIBILOF ISLANDS AND A MORE
ROBUST SHORTWAVE JUST OFF THE KAMCHATKA COAST EMBEDDED IN A BROAD
LONGWAVE TROUGH PATTERN.
MODEL GUIDANCE SUGGESTS THAT THE COMBINATION OF FORCING FROM THE
EASTERN MOST SHORTWAVE OVER THE PRIBILOF ISLANDS AND AN AREA OF
DISTURBED WEATHER TRACKING JUST SOUTH OF THE EASTERN ALEUTIANS
WILL LEAD TO CYCLOGENESIS WEDNESDAY MORNING SOUTH OF THE ALASKA
PENINSULA AND KODIAK ISLAND. AT THE SAME TIME, A FAST MOVING WAVE
OF LOW PRESSURE SLIDES JUST SOUTH OF THE CENTRAL ALEUTIANS WITH
SOME OF THE MODELS SHOWING THE NORTHERN MOST AREA OF ITS
PRECIPITATION SHIELD CLIPPING ADAK AND ATKA. THIS FEATURE EXITS
THE REGION BY WEDNESDAY AFTERNOON, WITH HIGH PRESSURE QUICKLY
BUILDING IN ACROSS THE BERING WITH FOG AND LOW STRATUS IN ITS
WAKE. GUIDANCE DIVERGES ON TIMING OF THE NEXT CHANCE OF
PRECIPITATION FOR THE WESTERN ALEUTIANS. BY THURSDAY OR SO, COLD
AIR ADVECTION ARRIVES FROM THE NORTHWEST TO SOUTHWEST ALASKA,
KEEPING TEMPERATURES SEVERAL DEGREES BELOW AVERAGE. SOME MODELS
LIKE THE GFS ARE SHOWING A LOW PRESSURE SYSTEM ARRIVING BY
THURSDAY AFTERNOON, AND OTHERS LIKE THE CANADIAN-NH HOLDING OFF
UNTIL SOME TIME ON SATURDAY. THE MAIN FORECAST CHALLENGE LOOKS TO
BE TIMING OUT THE ARRIVAL OF THE AFOREMENTIONED KAMCHATKA
SHORTWAVE THAT WILL MOVE EASTWARD OVER THE SHORT TERM. THE AIRMASS
OVER SOUTHWEST ALASKA LOOKS TO MODIFY SOME TIME THIS WEEKEND,
RETURNING THE AREA TO AVERAGE TEMPERATURES.
-AM
.LONG TERM FORECAST (DAYS 4 THROUGH 7: SATURDAY THROUGH
TUESDAY)...
SATURDAY SHOWS A RIDGE PRESENT IN THE BERING. THIS MEANS MORE
FOG/STRATUS FOR THAT REGION AS WELL AS CALM WINDS AND LOWER RAIN
CHANCES. NORTHWEST FLOW WILL ALLOW FOR GAP WINDS IN THE EASTERN
ALEUTIANS/ALASKA PENINSULA REGIONS. THESE GAP WINDS WILL LAST
UNTIL SUNDAY. SOUTHCENTRAL ALASKA SEES A COL MOVE IN AS AN UPPER
LEVEL LOW EXITS TO THE SOUTHEAST. THIS PATTERN CONTINUES THROUGH
NEXT TUESDAY. IT IS UNCERTAIN, BUT THERE MAY BE SOME EMBEDDED
SHORTWAVES PASSING THROUGH THE RIDGE IN THE BERING WHICH WOULD
ALLOW FOR SOME BRIEF BURSTS OF RAINFALL IN THE ALEUTIANS. EVEN SO,
WEATHER SHOULD BE MOSTLY UNEVENTFUL THROUGH TUESDAY. SOUTHCENTRAL
WILL ALSO BE ON THE QUIETER SIDE AS SLACK FLOW REMAINS IN PLACE
THROUGH TUESDAY. WEDNESDAY SEES A LONGWAVE TROUGH PUSH IN FROM THE
WEST. THIS COULD MEAN HIGHER RAIN CHANCES AS WELL AS GUSTY WINDS
NOT ONLY IN THE BERING, BUT ALSO THE SOUTHWEST MAINLAND, AND EVEN
INTO SOUTHCENTRAL. UNCERTAINTY REMAINS HIGH WITH THIS SCENARIO,
WHICH MAY CHANGE ON A WHIM.
-JAR
AVIATION
PANC...VFR CONDITIONS AND LIGHT WINDS WILL PERSIST. SOME MODEL
GUIDANCE BRINGS IN A BRIEF PERIOD OF GUSTY S-SE WINDS THIS
EVENING. HOWEVER, BASED ON THE PATTERN, AM DISCOUNTING THIS AND
STICKING WITH A MORE TRADITIONAL SEA BREEZE DIRECTION AND LIGHTER
WINDS. A WEAK UPPER LEVEL SHORT-WAVE WILL MOVE UP COOK INLET ON
WEDNESDAY, BUT EXPECT MOST (IF NOT ALL OF THE RAIN) TO REMAIN TO
THE SOUTH. EVEN IF RAIN DOES MAKE IT INTO THE TERMINAL, EXPECT
CEILINGS TO REMAIN VFR.
-SEB
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