681
FXAK68 PAFC 170041
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
441 PM AKDT THU JUL 16 2026
SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3)
PRECIPITATION THAT HAS OVERSPREAD THE KENAI PENINSULA, ANCHORAGE,
AND THE MATSU THIS AFTERNOON WILL CONTINUE TO SPREAD EAST INTO
THE COPPER VALLEY LATE THIS EVENING AND OVERNIGHT. THE SURFACE
LOW, CURRENTLY CENTERED JUST WEST OF KODIAK ISLAND, WILL CONTINUE
TO TRACK NORTHEAST ALONG THE EASTERN KENAI AS IT WEAKENS THROUGH
FRIDAY WHILE THE POTENT SHORTWAVE IN THE UPPER LEVELS PUSHES NORTH
THROUGH THE REGION TONIGHT. FOR FRIDAY, EXPECT REMNANT SHOWERY
RAIN AS SUBSEQUENT, WEAKER SHORTWAVES ROTATE THROUGH THE LONGWAVE
PATTERN PROVIDING CONTINUED WEAK LIFT COUPLED WITH MARGINAL
INSTABILITY.
FOR SATURDAY, THE PATTERN BECOMES HIGHLY AMPLIFIED AS AN UPPER
LOW IN THE SOUTHEASTERN BERING DEEPENS WHILE RIDGING BUILDS ACROSS
THE ALCAN BORDER. THIS WILL RESULT IN A NORTHWARD SURGE OF WARM
PACIFIC AIR AND MOISTURE FROM KODIAK ISLAND NORTH INTO THE MATSU
VALLEYS AS THE FRONTAL SYSTEM STALLS IN THE GULF AS THE RIDGE TO
THE EAST HOLDS. THIS WILL BRING THE NEXT ROUND OF PROLONGED,
WIDESPREAD RAIN TO THESE AREAS WHILE THE COPPER VALLEY LOOKS TO
STAY RELATIVELY DRY THROUGH THE WEEKEND. GAP WINDS WILL BE ON AND
OFF IN A DIURNAL CYCLE MOST DAYS WITH A COASTAL RIDGE GRADUALLY
STRENGTHENING THROUGH THE FORECAST PERIOD.
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (DAYS
1 THROUGH 3: TONIGHT THROUGH SUNDAY)...
THE PATTERN ACROSS THE BERING, ALEUTIANS, AND SOUTHWEST ALASKA
REMAINS ACTIVE THROUGH THE SHORT TERM, BUT IS ON TRACK. CURRENTLY,
A LOW PRESSURE SYSTEM CENTERED OVER THE ALASKA PENINSULA IS
SENDING A STRATIFORM SHIELD OF RAIN ACROSS THE ALASKA PENINSULA
AND SOUTHWEST ALASKA. CLOUDS AND RAINFALL AS EXPECTED HAVE HELD
TEMPERATURES DOWN TODAY ACROSS THE REGION, WITH DAYTIME HIGH
TEMPERATURES TOPPING OUT IN THE LOW TO MID 50S FOR MOST. THIS
SYSTEM WILL BE MOVING EAST AND EXITING INTO THE GULF TONIGHT, BUT
THE COMBINATION OF RAINFALL AND CLOUD COVER WILL KEEP OVERNIGHT
LOW TEMPERATURES ELEVATED IN THE MID TO UPPER 40S.
ALOFT, THE FEATURE DRIVING WEATHER FOR THE SHORT TERM IS A LARGE,
AMPLIFIED, UPPER LEVEL TROUGH THAT HAS CONSOLIDATED OVER THE
EASTERN BERING SEA AND WESTERN ALASKA. WITH ONE WAVE ROUNDING THE
TROUGH AND MOVING EAST WITH THE CURRENT LOW, ANOTHER WAVE IS
PROGGED TO QUICKLY DIG SOUTHEASTWARD FROM EASTERN RUSSIA TONIGHT.
AT THE SURFACE, DEEPENING OF LOW PRESSURE IS INDICATED IN THE
GLOBAL MODELS AS THE SURFACE LOW ALIGNS WITH THE SHORTWAVE'S UPPER
LEVEL FORCING. HENCEFORTH, THERE IS HIGH CONFIDENCE IN THE SYSTEM
STRENGTHENING INTO A GALE FORCE LOW AND ITS PRECIPITATION
SHIELD/QPF FIELD EXPANDING AS IT DOES SO. THE TREND-LINE OVER THE
PAST FEW GLOBAL MODEL RUNS IS FOR AN INCREASINGLY STRONGER
SYSTEM, AND WIDESPREAD GALES ARE EXPECTED FROM ATKA TO NIKOLSKI
AND EVENTUALLY UNALASKA AND AKUTAN AS FRIDAY MORNING WEARS ON.
THIS SYSTEM HAS ALSO TRENDED WETTER AS WELL, SO HAVE INCREASED QPF
FOR THIS FORECAST PACKAGE TO 0.5 TO 1 INCH OF RAINFALL FROM
NIKOLSKI TO SAND POINT FROM FRIDAY MORNING TO FRIDAY EVENING.
AS THIS LOW BECOMES VERTICALLY STACKED AND OCCLUDES AS IT
APPROACHES THE ALASKA PENINSULA, ANY REMAINING GALES WILL MOST
LIKELY DECREASE TO SMALL CRAFT WINDS. MODELS SHOW A SWATH OF HIGH
END SMALL CRAFT WINDS ON THE BACKSIDE OF THIS SYSTEM THAT BEGIN TO
MOVE ACROSS THE PRIBILOF ISLANDS FRIDAY EVENING. AS THE LOW
WEAKENS FURTHER, WINDS WILL DECREASE THROUGH SATURDAY MORNING FOR
THE PRIBILOF ISLANDS. AS THE LOW CONTINUES TO MOVE EASTWARD AND
JUST NORTH OF THE ALASKA PENINSULA, KAMISHAK GAP WINDS INCREASE
SATURDAY EVENING, GIVING LOCATIONS LIKE ILIAMNA BREEZY CONDITIONS.
THIS UPTICK IN WINDS IS ON TRACK TO BE SHORT LIVED AS THE LOW
BACKS NORTHWESTWARD AND MOVES NORTH UP THE SOUTHWEST ALASKA
COASTLINE.
THE SYNOPTIC SETUP OF THE LARGE UPPER TROUGH OVER THE EASTERN
BERING SEA AND WESTERN ALASKA REMAINS IN PLACE THROUGH SUNDAY, AND
SOME OF THE MODEL GUIDANCE DEPICTS ANOTHER SURFACE LOW MOVING
SOUTHEASTWARD ACROSS THE BERING SUNDAY AFTERNOON FROM RUSSIA. THAT
SAID, THERE IS QUITE A SPREAD IN POSITIONING AND TIMING OF THIS
LOW, SO DETAILS REGARDING THIS SYSTEM IS OF LOWER CONFIDENCE AT
THIS TIME. STAY TUNED.
-AM
.LONG TERM FORECAST (DAYS 4 THROUGH 7: MONDAY THROUGH
THURSDAY)...
PERSISTENCE REMAINS THE KEYWORD FOR THE LONG-TERM PERIOD. THERE
CONTINUES TO BE A STRONG SIGNAL IN THE GLOBAL MODELS OF A SLOW
MOVING, HIGHLY AMPLIFIED, UPPER LEVEL TROUGH CONSOLIDATING ALONG
165TH WEST MERIDIAN AND LINGERING ACROSS MUCH OF ALASKA WELL INTO
THE MIDDLE OF THE UPCOMING WORKWEEK. SMALLER SCALE DETAILS ARE
LESS CERTAIN, ESPECIALLY WITH EMBEDDED SHORTWAVES ROUNDING THE
BASE OF THE TROUGH AND MOVING INTO THE GULF OF ALASKA, WHERE
MODERATE STORM DEVELOPMENT IS POSSIBLE OVER THE SOUTHERN BERING
SEA AND NORTHERN GULF. THIS PATTERN SUPPORTS AN EXTENDED UNSETTLED
STRETCH OF DAILY RAIN CHANCES REGION WIDE THOUGH PRECIPITATION
WILL TURN MORE WIDESPREAD, ORGANIZED AND WINDIER FROM THE
SOUTHWEST THROUGH PRINCE WILLIAM SOUND AND SOUTHCENTRAL ALASKA AS
MOISTURE DEEPENS AND SHIFTS NORTHWARD. A MULTI-DAY HEAVY RAINFALL
THREAT HAS BEEN HIGHLIGHTED FOR THOSE AREAS NEXT WEEK. THE MAIN
FORECAST CHALLENGE THROUGH THE LONG TERM REMAINS THE TIMING OF THE
SHORTWAVES (WHICH WILL DRIVE PERIODS OF MODERATE RAINFALL)
ROTATING AROUND THE LARGE UPPER LEVEL TROUGH COMPLEX THAT WILL
ANCHOR OVER THE EASTERN BERING SEA.
ALONG THE COASTAL WATERS, PARTICULARLY THE GULF OF ALASKA AND
SOUTHERN BERING SEA, STRENGTHENING SYSTEMS CARRY THE POTENTIAL FOR
INCREASING WINDS AND ROUGHER SEAS. THESE CONDITIONS ARE LIKELY TO
CREATE HAZARDOUS MARINE ENVIRONMENT FOR BOATING, COMMERCIAL
FISHING AND VESSEL OPERATIONS, WITH HEAVIER SEAS AND GUSTY WINDS
POSSIBLE. OVERALL, THE WETTER AND WINDIER PATTERN ACROSS SOUTHERN
AND COASTAL ALASKA WILL REQUIRE ATTENTION TO ACCUMULATING RAINFALL
IMPACTS AND MARINE HAZARDS INTO THE MIDDLE OF NEXT WEEK.
-DD
AVIATION
PANC...VFR CONDITIONS WILL PERSIST THROUGH MOST OF THE TAF PERIOD.
THERE WILL LIKELY BE A BRIEF PERIOD (3 TO 4 HOURS) OF GUSTY
SOUTHEASTERLY WINDS LATE THIS AFTERNOON THROUGH EARLY EVENING,
BUT WITH COOL TEMPERATURES AND RAIN FALLING, WINDS ARE SOMETIMES
WEAKER THAN EXPECTED IN THIS SCENARIO. IN ANY CASE, IF GUSTY WINDS
DEVELOP, THEY WILL QUICKLY DIMINISH LATER THIS EVENING. THE LOW
LEVEL SOUTHEASTERLY FLOW WILL ENSURE CEILINGS STAY SAFELY IN THE
VFR CATEGORY THIS AFTERNOON AND EVENING.
AREAS OF RAIN AND SOME LOWERING OF CEILINGS ARE ALSO LIKELY BY
LATE THURSDAY MORNING AHEAD OF A LOW APPROACHING SOUTHCENTRAL FROM
THE BRISTOL BAY VICINITY. THE HIGH PROBABILITY IS FOR LOW END VFR
OR HIGH END MVFR CONDITIONS TO SETTLE IN FOR MUCH OF THE DAY.
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