018
FXAK68 PAFC 071312
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
512 AM AKDT THU AUG 7 2025
SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3)
DISCUSSION:
RAIN HAS BEEN STEADILY SPREADING NORTHWARDS THIS MORNING ACROSS THE
WESTERN GULF, KENAI PENINSULA, AND COOK INLET AS THE FRONT CONTINUES
TO PUSH TOWARDS THE SOUTHCENTRAL COAST. PER SATELLITE IMAGERY, AND
SURFACE AND BUOY OBSERVATIONS, THE FRONT APPEARS TO BE MOVING A BIT
FASTER THAN THE MODELS HAVE HAD THE FRONT AND THE ASSOCIATED
PRECIPITATION ARRIVING. WINDS AHEAD OF THE FRONT HAVE BECOME QUITE
GUSTY, ESPECIALLY FOR SOME OF THE TYPICAL EAST/WEST GAP ZONES. A
DEVELOPING SURFACE LOW NEAR THE BARREN ISLANDS HAS BEGUN TO SHIFT
GUSTY TURNAGAIN ARM WINDS DOWN INLET WITH LIGHT EASTERLY TO
NORTHERLY WINDS MOVING BACK INTO THE ANCHORAGE BOWL. THIS INITIAL
PUSH OF RAIN WILL BEGIN TO SCATTER OUT ALONG THE WESTERN KENAI
PENINSULA UP THROUGH THE MAT VALLEY AS THE 850 MB JET MOVES OVER THE
KENAI AND CHUGACH MOUNTAINS RESULTING IN MODEST SOUTHEASTERLY CROSS-
BARRIER FLOW AND DOWNSLOPING FOR LATER THIS MORNING AND AFTERNOON.
AS THE WINDS DECREASE AND DOWNSLOPING WEAKENS...SHOULD SEE SOME
SHOWERS RETURN BY TONIGHT. COASTAL AREAS WILL SEE THE BULK OF THE
RAINFALL TODAY WITH A GOOD FETCH OF MOISTURE UNDER STRONG
SOUTHEASTERLY FLOW. GALE FORCE WINDS WILL CONTINUE ACROSS THE BARREN
ISLANDS THIS MORNING WITH A BARRIER JET OF GALES SETTING UP ACROSS
THE NORTHERN GULF COAST BY THIS AFTERNOON. THESE WINDS WILL
GRADUALLY DECREASE OVERNIGHT AS THE FRONT STARTS FRONT BEGINS TO
LIFT INLAND AND STALLS. THE UNSETTLED CONDITIONS CONTINUING THE REST
OF THE WEEK AND WEEKEND AS THE UPPER LOW LINGERS OVER THE AKPEN
BEFORE LIFTING NORTH INTO THE INTERIOR AS AN OPEN WAVE, AND SEVERAL
MORE UPPER-LEVEL DISTURBANCES MOVE THROUGH AS A TROUGH BEGINS TO
DIVE SOUTHWARD ACROSS WESTERN ALASKA.
- PP
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS
(DAYS 1 THROUGH 3: TODAY THROUGH SATURDAY NIGHT)...
BROAD LOW PRESSURE ASSOCIATED WITH THE REMNANTS OF EX-TYPHOON
KROSA IS CENTERED JUST SOUTH OF THE SOUTHERN TIP OF THE ALASKA
PENINSULA THIS MORNING. AN OCCLUDED FRONT WRAPS ACROSS THE
EASTERN/CENTRAL BERING SEA AND OVER SOUTHWEST ALASKA, WHERE IT IS
PRODUCING LIGHT RAINFALL. COOL AND WET CONDITIONS ARE FORECAST
TODAY, WHICH WILL KEEP HIGH TEMPERATURES CAPPED IN THE UPPER 50S
TO MID 60S ACROSS SOUTHWEST ALASKA. PRECIPITATION BECOMES SHOWERY
THIS AFTERNOON/EVENING AS THE FRONT WEAKENS MORE OR LESS IN PLACE,
AND GUSTY SOUTHEASTERLY WINDS DIMINISH. THE LOW OPENS UP INTO A
TROUGH TONIGHT SOUTH OF THE ALASKA PENINSULA AND A BRIEF DRY
PERIOD IS EXPECTED FRIDAY MORNING, WITH ONLY ISOLATED SHOWER
ACTIVITY LINGERING IN THE LOWER KUSKOKWIM VALLEY AND DELTA.
TEMPERATURES OVER SOUTHWEST ALASKA REBOUND A BIT ON FRIDAY AS THE
INFLUENCE OF LOW PRESSURE WANES AND DRIER, SUNNIER CONDITIONS
PREVAIL. NORTHERLY WINDS SPREAD ACROSS THE BERING SEA AND - AT
LEAST INITIALLY - WIDESPREAD STRATUS AND AREAS OF FOG LINGER WITH
NO SIGNIFICANT PUSH OF COOLER AIR.
HOWEVER, ON FRIDAY, UPPER-LEVEL LOW PRESSURE DIVES SOUTH FROM THE
ARCTIC AND COLD AIR BEGINS TO SWEEP ACROSS THE NORTHERN BERING SEA
AND INTO THE KUSKOKWIM DELTA. THE FRONTAL ZONE PROMOTES A RENEWED
BAND OF RAIN OVER THE DELTA BEGINNING FRIDAY EVENING, WHICH THEN
SWEEPS EAST ACROSS SOUTHWEST ALASKA THROUGH SATURDAY. THE AIR MASS
BROUGHT ALONG BY THE UPPER LOW IS SIGNIFICANTLY COOLER THAN WHAT
HAS BEEN SEEN IN THE REGION RECENTLY AND HIGH TEMPERATURES MAY NOT
EVEN CRACK 50 DEGREES ON SATURDAY IN THE KUSKOKWIM DELTA AND
PARTS OF THE LOWER KUSKOKWIM VALLEY. THE UPPER LOW QUICKLY STALLS
OUT OVER THE SEWARD PENINSULA, WHICH MEANS THAT FORCING IS
STRONGEST FOR PRECIPITATION OVER NORTHERN PORTIONS OF THE AREA.
COASTAL BRISTOL BAY MAY REMAIN RELATIVELY DRY EVEN AS COLD AIR
SWEEPS AS FAR SOUTH AS THE EASTERN ALEUTIANS AND ALASKA PENINSULA
THIS WEEKEND. THIS BURST OF COLD AIR WILL HAVE THE POTENTIAL TO
SCOUR OUT SOME OF THE PESKY FOG AND STRATUS THAT HAS BEEN PRESENT
ACROSS THE BERING SEA AS OF LATE.
LONG TERM FORECAST (DAYS 4 THROUGH 7: SUNDAY THROUGH WEDNESDAY)
AN UPPER-LEVEL TROUGH ORIGINATING FROM THE ARCTIC DIGS ACROSS THE
SOUTHERN HALF OF MAINLAND ALASKA ON SUNDAY AS A LOW MOVES
NORTHEASTWARD ACROSS THE GULF OF ALASKA. THE RESULT OF BOTH OF THESE
SYSTEMS IS A DAY OF WIDESPREAD RAIN ACROSS MUCH OF SOUTHERN AK.
MODEL SPREAD AND THUS LACK OF FORECAST CONFIDENCE INCREASES
SIGNIFICANTLY BY AND AFTER LATE SUNDAY, WITH THE ECMWF KEEPING THE
TROUGH AN OPEN WAVE AND HAVING IT LIFT QUICKLY INTO YUKON.
MEANWHILE, GFS AND CANADIAN MODELS AND ENSEMBLE MEANS ADVERTISE A
DEEPER, SLOWER, AND CLOSED-OFF LOW FOR THE AREA. UPPER-LEVEL RIDGING
THEN AMPLIFIES ACROSS SOUTHCENTRAL BY TUESDAY IN WAKE OF THE TROUGH.
THE ECMWF, THE PREFERRED MODEL INTO NEXT WEEK, DOES HAVE A CLOSED
LOW MOVING UNDER THE RIDGE AND THROUGH THE GULF LATE MONDAY INTO
TUESDAY.
HIGH PRESSURE PREVAILS ACROSS MUCH OF THE EASTERN BERING INTO THE YK
DELTA FROM LATE SUNDAY INTO THE START OF THE NEXT WORK WEEK. THE
ECMWF HAS A MORE SIGNIFICANT LOW DEVELOPING ACROSS THE NORTH PACIFIC
AND MOVING NORTHWARD INTO THE CENTRAL ALEUTIANS AND INTO THE EASTERN
BERING, THIS SYSTEM MAY BRING STRONG WINDS TO THOSE LOCATIONS SHOULD
IT MATERIALIZE.
THE BOTTOM LINE WITH ALL THESE FEATURES IS THAT AN ACTIVE WEATHER
PATTERN WILL CONTINUE FROM THE BERING SEA THROUGH THE GULF AND INTO
SOUTHCENTRAL AK. RAIN IS LIKELY ACROSS MUCH OF SOUTHERN AK SUN/MON
BEFORE DRYING OUT WITH A RIDGE AND THEN POSSIBLY RETURNING TO
COASTAL LOCATIONS BY TUESDAY, THOUGH UNCERTAINTY IS LARGE WITH
TIMING GIVEN THE SPREAD IN FEATURES. THE BERING REMAINS ACTIVE,
PARTICULARLY THE CENTRAL AND EASTERN ALEUTIANS, AS A SERIES OF
TROUGHS ROTATE ACROSS. TEMPERATURES ACROSS MUCH OF SOUTHERN AK WILL
BE ON THE COOL SIDE SUNDAY AND MONDAY BEFORE WARMING TO OR ABOVE
AVERAGE TUESDAY AND WEDNESDAY.
-BROWN
AVIATION
PANC...STEADY, LIGHT RAIN THIS MORNING WILL TAPER OFF BY LATE
MORNING THROUGH EARLY AFTERNOON AS SOUTHEASTERLY CROSS-BARRIER
WINDS SET-UP OVER THE CHUGACH MOUNTAINS. GUSTY TURNAGAIN ARM
WINDS HAVE TURNED DOWN INLET WITH LIGHT WINDS MOVING BACK INTO THE
TERMINAL. AS WINDS INCREASE OVER THE MOUNTAINS AND LIGHT SURFACE
WINDS, A PERIOD OF LLWS IS POSSIBLE BEFORE CROSS-BARRIER WINDS
GRADUALLY DECREASE THIS EVENING. INCREASED CHANCES FOR SCATTERED
RAIN SHOWERS RETURN AFTER 03Z WITH CEILINGS AND VISIBILITY
GENERALLY REMAINING VFR TO MVFR.
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