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FXAK68 PAFC 161533
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
733 AM AKDT THU JUL 16 2026
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3: TODAY
THROUGH SUNDAY)...
PRECIPITATION WILL SPREAD FROM SOUTHWEST TO NORTHEAST THROUGH THE
DAY TODAY AS A STORM CURRENTLY CENTERED NORTH OF UNALASKA DRIVES
TOWARDS BRISTOL BAY THIS AFTERNOON. RAIN SHOULD ARRIVE OVER THE
KENAI PENINSULA, ANCHORAGE AND THE MAT-SU VALLEYS EARLY THIS
AFTERNOON BEFORE SPREADING EAST INTO THE COPPER VALLEY LATE THIS
EVENING AND OVERNIGHT. WHILE THE SURFACE LOW WILL SPLIT AND
WEAKEN, THE UPPER LEVEL FEATURE WILL PROVIDE PLENTY OF FORCING FOR
ANOTHER ROUND OF WIDESPREAD RAIN. FOR FRIDAY, EXPECT REMNANT
SHOWERY RAIN AS AN AREA OF WEAK LIFT AND MARGINAL INSTABILITY
MOVES OVERHEAD WITH SLIGHTLY STEEPER LAPSE RATES ALOFT. FOR
SATURDAY, A DEEP UPPER LOW OVER THE BERING WILL DRIVE SOUTH,
AMPLIFYING THE OVERALL PATTERN, AND TAPPING INTO MOISTURE FARTHER
SOUTH INTO THE PACIFIC. WITH THE PATTERN AMPLIFICATION, SOME
RIDGING WILL BE ABLE TO DEVELOP NEAR THE ALCAN BORDER, WHICH WILL
KEEP THE COPPER VALLEY DRIER INTO THE COMING WEEKEND, WHILE KODIAK
NORTH INTO THE MAT-SU VALLEYS WILL RECEIVE THE BRUNT OF THE
PRECIPITATION. 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)...
AS BEFORE, LONGWAVE TROUGHING IS OVER THE BERING AND WESTERN
ALASKA. THIS IS ALLOWING FOR CONTINUED ACTIVE WEATHER ACROSS
SOUTHWEST ALASKA DUE TO MULTIPLE SURFACE FEATURES TRAVERSING THE
BERING AND MOVING INTO THE MAINLAND. THIS ACTIVE PATTERN WILL
CONTINUE INTO THE WEEKEND AND LIKELY INTO NEXT WEEK.
FOR THE SPECIFICS, A LOW IS CURRENTLY OVER THE ALASKA PENINSULA.
THIS IS ALLOWING FOR STEADY RAINFALL WHICH WILL MOVE INTO THE
MAINLAND BY THIS (THURSDAY) AFTERNOON. THE ALEUTIANS ARE SEEING A
BREAK IN STEADY RAINFALL AS THE AREA IS SITTING BETWEEN SYSTEMS.
SPEAKING OF THE NEXT SYSTEM, A LOW WILL DROP INTO THE BERING BY
TONIGHT OR EARLY FRIDAY. ITS FRONT WILL SPREAD OVER THE ALEUTIANS
BY FRIDAY AFTERNOON, BRINGING STEADY RAINFALL AND GUSTY WINDS.
THIS LOW IS TRENDING STRONGER THAN BEFORE AND GALEFORCE WINDS ARE
NOW EXPECTED OVER THE ALEUTIANS, PARTICULARLY OVER BAYS AND
PASSES. THE LOW WILL SLOWLY MOVE EASTWARD AND WILL REACH BRISTOL
BAY BY SATURDAY. THIS WILL ALLOW FOR WIDESPREAD RAINFALL TO MOVE
INTO THE ALREADY SATURATED MAINLAND. WIND SPEEDS WILL ALSO
INCREASE FOR THE MAINLAND, PARTICULARLY OUT OF THE KAMISHAK GAP,
WHICH WILL LEAD TO GUSTY WINDS OVER ILIAMNA.
THE UPPER LOW WILL SIT IN PLACE THROUGH SUNDAY, WHICH WILL
PROVIDE LIFT AND ALLOW FOR RAINFALL TO CONTINUE OVER SOUTHWEST
ALASKA. AS MENTIONED BEFORE, THE CURRENT THINKING IS THAT THIS
PATTERN WILL HOLD INTO NEXT WEEK, SO PREPARE FOR MORE WIDESPREAD
RAINFALL.
-JAR
LONG TERM FORECAST (DAYS 4 THROUGH 7: SUNDAY THROUGH WEDNESDAY)
VERY LITTLE CHANGE FROM THE PREVIOUS DISCUSSION. THERE IS 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 NEXT 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
IS TIMING OUT 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 EARLY NEXT WEEK.
-DD/AM
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