163
FXAK68 PAFC 200034
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
434 PM AKDT SUN JUL 19 2026
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3/TONIGHT
THROUGH WEDNESDAY)...
A HIGH AMPLITUDE TROUGH IS CENTERED ALONG THE WEST COAST OF MAINLAND
ALASKA AND SOUTHWARD WELL DOWN INTO THE PACIFIC (AROUND 40N
LATITUDE), WITH A CORRESPONDING HIGH AMPLITUDE DOWNSTREAM RIDGE
OVER SOUTHEAST AK AND THE YUKON. IN BETWEEN IS AN ATMOSPHERIC
RIVER SUPPORTED BY A 100+ KT MERIDIONAL JET STREAK. A NARROW BAND
OF MODERATE TO HEAVY RAIN HAS BEEN SITTING OVER THE SAME AREAS FOR
THE FIRST HALF OF TODAY, FROM THE KENAI PENINSULA TO ANCHORAGE
AND THE SUSITNA VALLEY. A SHORT-WAVE MOVING THROUGH THE BASE OF
THE TROUGH IS NOW CAUSING THE TROUGH TO BECOME SLOWLY TAKE ON A
NEGATIVE TILT. AS A RESULT, LOW LEVEL SOUTHEAST FLOW IS INCREASING
ACROSS THE KENAI PENINSULA LEADING TO AN EXPANDING DOWNSLOPE HOLE
ACROSS THE INTERIOR WESTERN KENAI, ANCHORAGE, AND THE MATANUSKA
VALLEY. RAIN HAS ENDED ACROSS MOST OF ANCHORAGE (AS OF 2PM),
LINGERING OVER FAR WESTERN ANCHORAGE. AFTER RAPID RISES ALONG
CAMPBELL AND CHESTER CREEKS, WATER LEVELS ARE NOW QUICKLY FALLING.
MEANWHILE, RAINFALL RATES HAVE PICKED UP FOR MUCH OF COASTAL
KENAI PENINSULA ON UP TO THE WESTERN TO CENTRAL SUSITNA VALLEY
(INCLUDING THE PARKS HIGHWAY CORRIDOR). A FLOOD WARNING IS IN
EFFECT FOR SEWARD UNTIL 10AM TUESDAY FOR URBAN AND RIVER/STREAM
FLOODING AND A FLOOD ADVISORY IS IN EFFECT FOR THE YENTNA RIVER
FOR MINOR FLOODING OF LOW LYING AREAS ALONG THE RIVER. WARMER AND
DRIER CONDITIONS ARE BEING OBSERVED IN THE COPPER RIVER BASIN,
WITH PARTLY SUNNY SKIES. LASTLY, ELEVATED WINDS AND WAVES CAN BE
FOUND AHEAD OF A SURFACE FRONT FROM THE NORTHERN GULF COASTAL
WATERS INTO PRINCE WILLIAM SOUND, WITH SOUTHEASTERLY GAP WINDS
EXTENDING INLAND.
THE UPPER LEVEL TROUGH WILL CONTINUE TO BECOME MORE NEGATIVELY
TILTED TONIGHT WHILE SLOWLY PROGRESSING NORTHEASTWARD. HEAVY RAIN
ACROSS THE KENAI PENINSULA AND SUSITNA VALLEY WILL SHIFT BACK
NORTH AND EAST OVERNIGHT TONIGHT THROUGH MONDAY. IN ADDITION TO
THE AFOREMENTIONED AREAS WHERE FLOODING IS EXPECTED, OTHER AREAS
TO CLOSELY WATCH FOR POTENTIAL MINOR FLOODING INCLUDE THE
SOUTHWESTERN KENAI (ANCHOR RIVER), OTHER RIVERS AND STREAMS IN THE
SUSITNA VALLEY, AND ANCHORAGE (FOR URBAN FLOODING AS RAIN SPREADS
BACK IN ON MONDAY). THE UPPER TROUGH WILL WEAKEN AS IT CONTINUES
NORTH AND EAST MONDAY NIGHT THROUGH TUESDAY. THE UPPER JET (AND
ATMOSPHERIC RIVER) WILL ALSO WEAKEN WITH TIME. AS A RESULT, EXPECT
A NARROW BAND OF MUCH LIGHTER RAIN TO SPREAD ACROSS THE THE COPPER
RIVER BASIN MONDAY NIGHT THROUGH TUESDAY MORNING.
THERE WILL BE A BRIEF BREAK IN RAINFALL BEHIND THE UPPER TROUGH
(24 HOURS OR LESS) BEFORE THE NEXT STORM APPROACHES FROM THE
BERING SEA IN CONTINUED PROGRESSIVE FLOW ALOFT. RAIN WILL REACH
KODIAK ISLAND MONDAY NIGHT, THEN OVERSPREAD MUCH OF SOUTHCENTRAL
ON TUESDAY. THE UPPER TROUGH WILL MOVE THROUGH VERY QUICKLY, SO
THIS WILL BE A GLANCING BLOW OF RAIN, WITH THE SYSTEM EXITING TO
THE NORTH AND EAST ON WEDNESDAY MORNING. MODELS HAVE BEEN WAFFLING
WITH THE TRACK OF THE NEXT LOW ACROSS THE BERING SEA, BUT THE
LATEST GUIDANCE SEEMS TO BE LOCKING INTO A SIMILAR TRACK. BASED ON
THIS, EXPECT ANOTHER ROUND OF RAIN WEDNESDAY NIGHT THROUGH
THURSDAY.
-SEB
.SHORT TERM FORECAST SOUTHWEST ALASKA AND BERING SEA/ALEUTIANS
(DAYS 1 THROUGH 3)...
A BRISTOL BAY LOW WILL MOVE NORTHWARD UP THE MAINLAND COAST
CONTINUING TODAY'S SOUTHERLY AND EASTERLY WINDS AND RAIN SHOWERS
OVER SOUTHWEST ALASKA THROUGH TOMORROW EVENING. ANOTHER LOW MOVES
ACROSS THE ALEUTIANS EARLY THIS WEEK WITH A RIDGE AND MORE ZONAL
FLOW BEHIND IT.
TWELVE HOUR RAINFALL AMOUNTS AS OF 4:00PM TODAY ARE A FEW
HUNDREDTHS OF AN INCH OVER THE REGION WITH WIND GUSTS DURING THIS
TIME RANGING 20 TO 30 KNOTS IN SOUTHWEST ALASKA AS A LOW MOVES UP
THE COAST THEN INLAND. AS THIS LOW MOVES INLAND THIS EVENING,
MORE WIDESPREAD RAIN IS EXPECTED OVER THE KUSKOKWIM DELTA THROUGH
TOMORROW. SHORT-LIVED, WEAK RIDGING DIMINISHES THESE RAIN SHOWERS
FOR THE MAINLAND AND THE AK PEN LATE MONDAY AFTERNOON / EVENING.
ANOTHER ROUND OF RAIN ARRIVES TUESDAY.
A BAND OF THUNDERSTORMS ASSOCIATED WITH A SEPARATE LOW WILL
CONTINUE TO MOVE THROUGH THE FAR WESTERN BERING SEA INTO THIS
EVENING. THIS SEPARATE LOW PRESSURE SYSTEM MOVES OUT OF RUSSIA
AND INTO THE BERING SEA TODAY THROUGH TUESDAY BRINGING MORE
WIDESPREAD RAIN AND STRONG WINDS TO THE REGION. THIS SEPARATE LOW
MOVING THROUGH THE BERING SEA REACHES THE PRIBILOF ISLANDS TUESDAY
MORNING THEN MOVES IN A MORE EASTERLY DIRECTION TOWARDS THE
MAINLAND INTO TUESDAY EVENING. THIS BRINGS RAIN SHOWERS AND
SOUTHERLY TO SOUTHWESTERLY WINDS INTO THE PRIBILOFS, EASTERN
ALEUTIANS, AK PEN AND THE MAINLAND THROUGH WEDNESDAY. THE STRONG
SOUTHWESTERLY WINDS 20 TO 30 KNOTS BRINGING WAVE HEIGHTS TO 8 FEET
ALONG THE BRISTOL BAY COASTLINE DURING THIS TIME. ALSO, THIS WILL
COINCIDE WITH A CORE OF MODERATE TO HEAVY PRECIPITATION MOVES
THROUGH THE AREA FROM SOUTH OF THE PRIBILOFS TO THE EASTERN
ALEUTIANS / AK PEN AND THE MAINLAND.
ZONAL TO SOUTHWEST FLOW DOMINATES IN THE WESTERN BERING SEA MID-
WEEK WITH WARM TROPICAL AIR BRINGING SHORTWAVE ENERGY AND A
RESURGENCE OF RAIN ACROSS THE REGION.
- JOHNSTON
.LONG TERM FORECAST (DAYS 4 THROUGH 7: THURSDAY THROUGH
SUNDAY)...
A PATTERN CHANGE IS IN THE WORKS DURING THE LONG TERM PERIOD NEXT
WEEK. AN UPPER LOW AND FRONT WILL BE PROGRESSING THROUGH INTERIOR
ALASKA ON THURSDAY. BEHIND THIS FEATURE FORECAST MODELS ARE IN
SOMEWHAT GOOD AGREEMENT WITH THE DEVELOPMENT OF A BUILDING RIDGE
OF HIGH PRESSURE OVER THE SOUTHERN BERING ON FRIDAY. THE RIDGE
AMPLIFIES FURTHER OVER THE WEEKEND. FOR SOUTHCENTRAL, NORTHERLY
FLOW BEHIND THE DEPARTING UPPER LOW AND TROUGH WILL BRING IN DRIER
CONDITIONS AND A POTENTIAL BREAK FROM PERSISTENT RAIN CHANCES
OVER THE STATE. HIGH PRESSURE OVER THE BERING WILL FAVOR DRIER
CONDITIONS AS WELL. THE ONE CAVEAT WILL BE THE POTENTIAL FOR
SMALLER SHORTWAVE DISTURBANCES TO RIDE OVER THE TOP OF THE RIDGE
AND INTO SOUTHWEST ALASKA WITH RENEWED RAIN CHANCES ON SUNDAY.
-BL
AVIATION
PANC...STEADY RAIN WILL TEMPORARILY LET UP THIS EVENING, BUT WILL
RETURN DURING THE LATE OVERNIGHT AND INTENSIFY THROUGH MONDAY
MORNING. A PERIOD OF WINDS BLOWING OUT OF THE TURNAGAIN ARM IS
POSSIBLE, LIKELY SOMETIME BETWEEN 4Z AND 12Z TONIGHT, THOUGH
CONFIDENCE FOR TIMING AND EXACT MAGNITUDE FOR ANY PERIOD OF
GUSTIER WINDS REMAINS LOW. LLWS WILL REMAIN POSSIBLE UNTIL WINDS
AT THE SURFACE TURN OUT OF THE SOUTHEAST LATER THIS EVENING.
GENERALLY VFR CONDITIONS WILL PREVAIL UNTIL RAIN INTENSITY PICKS
UP EARLY MONDAY MORNING, LIKELY PUSHING CEILINGS AND VISIBILITY
DOWN INTO MVFR RANGE.
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