007
FXAK68 PAFC 131412
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
612 AM AKDT SUN SEP 13 2026
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3: TODAY
THROUGH TUESDAY)...
SOUTHCENTRAL NOW SITS NEAR THE CREST OF BROAD, LOW-AMPLITUDE RIDGE
OF HIGH PRESSURE EXTENDING ACROSS MUCH OF THE GULF AND SOUTHERN
MAINLAND. SOME PASSING UPPER LEVEL CIRRUS IS DRIFTING OVER THE
KENAI PENINSULA AND KODIAK ISLAND OUT AHEAD OF A SHORTWAVE
DISTURBANCE DRIFTING EAST INTO BRISTOL BAY. OTHERWISE, SKIES HAVE
REMAINED MOSTLY CLEAR DURING MUCH OF THE OVERNIGHT, ALLOWING THE
SURFACE TO RADIATE AND COOL INTO THE 30S TO LOW 40S OVER MANY OF
THE INTERIOR VALLEYS. PATCHY FOG, DENSE AT TIMES, HAS FORMED
ACROSS A GOOD PORTION OF THE MAT-SU VALLEYS, WESTERN KENAI
PENINSULA AND ANCHORAGE BOWL WHERE AIR HAS COOLED ENOUGH TO BECOME
FULLY SATURATED. KEEP AN EYE OUT FOR RAPID FLUCTUATIONS IN
VISIBILITY IF YOU HAVE ANY LOCAL TRAVEL PLANS DURING THE EARLY
MORNING HOURS TODAY.
LOOKING AHEAD, CONDITIONS ARE STILL POISED TO BECOME CONSIDERABLY
MORE UNSETTLED AS WE MOVE FORWARD INTO THE START OF NEXT WEEK.
EVEN SO, WE WILL MANAGE TO SQUEAK OUT ONE OR TWO MORE RELATIVELY
PLEASANT SEPTEMBER DAYS FOR THIS AFTERNOON INTO MONDAY AS THE
UPPER RIDGE CENTERED JUST OFF TO THE WEST CONTINUES TO AMPLIFY OUT
AHEAD OF OUR STORM SYSTEM OF INTEREST. PATCHY FOG AND LOW CLOUDS
WILL BREAK UP WITHIN A FEW HOURS PAST SUNRISE TODAY, BUT THERE IS
STILL SOME CHANCE FOR IT TO RETURN LATER TONIGHT. THE CHANCE FOR
FOG DOES LOOK LOWER COMPARED TO THIS MORNING, HOWEVER, THANKS TO
INCREASING CLOUD COVER MOVING IN ON THE LEADING EDGE OF AN
APPROACHING FRONT HEADING NORTH ACROSS THE GULF.
MOST OF THE DAY ON MONDAY WILL REMAIN ON THE DRY SIDE, BUT MID TO
UPPER LEVEL CLOUDS WILL REALLY START TO SPREAD IN AS A WARM FRONT
STEMMING FROM A DEVELOPING LOW OUT WEST LIFTS INTO THE KENAI
PENINSULA. LIGHT RAIN CHANCES ALONG THE FRONT WILL STEADILY
INCREASE BY THE AFTERNOON HOURS, FIRST ACROSS THE KENAI PENINSULA,
THEN SHIFTING NORTH INTO ANCHORAGE AND THE MAT-SU BY THIS EVENING.
RAIN WILL BEGIN TO SPREAD INTO THE COPPER BASIN AS THE FRONT
CONTINUES TO LIFT NORTH THROUGH MONDAY NIGHT, BUT MAY STRUGGLE TO
REACH THE GROUND AT LOWER ELEVATIONS IN THE VICINITY OF
GLENNALLEN.
BY TUESDAY, STRONG SOUTH TO SOUTHWEST FLOW WILL REALLY BEGIN TO
RAMP UP AS THE BERING LOW OUT WEST INTENSIFIES AS IT REACHES THE
COAST NEAR THE YUKON-KUSKOKWIM DELTA. VERY STRONG AND GUSTY
SOUTHERLY GAP WINDS WILL BEGIN BY TUESDAY MORNING AND THEN
INTENSIFY THROUGHOUT THE DAY AS THE LOW STARTS TO LIFT INTO THE
WESTERN INTERIOR AND HELPS TO TIGHTEN UP A SHARP SOUTHEAST TO
NORTHWEST PRESSURE GRADIENT ACROSS SOUTHCENTRAL. GUSTS OUT OF THE
TURNAGAIN ARM, KNIK AND COPPER VALLEYS COULD BECOME QUITE INTENSE,
PERHAPS REACHING AS MUCH AS 30 TO 50 MPH (AND LOCALLY HIGHER ALONG
THE HILLSIDE AND TURNAGAIN ARM) BY THE AFTERNOON HOURS ON TUESDAY.
THERE HAS BEEN QUITE A BIT OF SHIFTING AROUND IN THE MODELED
EVOLUTION OF THE LOW OUT WEST OVER THE PAST DAY OR TWO, BUT
CONFIDENCE FOR A MORE APPRECIABLE GAP WIND EVENT ON TUESDAY IS
BEGINNING TO INCREASE NONETHELESS. SOUTHERLY DOWNSLOPE FLOW CLOSE
TO THE SURFACE MAY ALSO BE ENOUGH TO DRY THINGS OUT IN THE LEE OF
THE MOUNTAINS TEMPORARILY ON TUESDAY MORNING, BUT EXPECT RAIN TO
FILL BACK IN JUST ABOUT EVERYWHERE ALONG AND WEST OF THE CHUGACH
MOUNTAINS AND KENAI PENINSULA BY THE AFTERNOON.
-AS
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (DAYS
1 THROUGH 3: SUNDAY MORNING THROUGH WEDNESDAY MORNING)...
A FRONT AND TROUGH AXIS REMAINS OVER BRISTOL BAY AND EXTENDS
SOUTHWEST BETWEEN ATKA AND NIKOLSKI AND CONTINUES INTO THE NORTH
PACIFIC. WINDS REMAIN RELATIVELY LIGHT THROUGH MONDAY MORNING WHEN
A SECOND LOW LIFTS ACROSS THE ALEUTIAN CHAIN AND REINFORCES THE
TROUGH OVER BRISTOL BAY. ASSOCIATED WITH THE FRONT ARE RAINFALL
AND SMALL CRAFT ADVISORY WINDS. IN AREAS WHERE RAIN IS ABSENT, FOG
AND LOW STRATUS WILL BE PREDOMINANT. THE FRONT AND PARADE OF
RAIN WILL DRAG SLOWLY ACROSS THE WESTERN ALASKA PENINSULA UNTIL
WEDNESDAY AFTERNOON, DUE TO A STRONG ~1033 MB NORTH PACIFIC RIDGE
SOUTH OF THE GULF OF ALASKA. BY TUESDAY AFTERNOON, THE RIDGE WILL
SLIDE EASTWARD ENOUGH TO ALLOW THE LOW CENTER INTO THE INTERIOR,
AND ITS FRONT TO PROCEED INTO THE NORTHERN GULF BY WEDNESDAY
MORNING.
FARTHER EAST ON WEDNESDAY MORNING, A LOW MOVES FROM KAMCHATKA INTO
THE WESTERN BERING. MODELS CONTINUE TO STRUGGLE WITH BOTH SURFACE
AND 500 MB FEATURES, SHOWING POOR RUN-TO-RUN CONSISTENCY WITH
REGARD TO THE TIMING AND LOCATION OF THE LOW. NORMALLY, THIS WOULD
NOT BE A BIG DEAL AS THE LOW BEING DEPICTED IS FAIRLY WEAK, BUT
MODELS ARE LATCHING ONTO THIS LOW CONTINUING TO DEEPEN AS IT
TRACKS NORTHEASTWARD ACROSS THE BERING AND INTO THE YUKON-
KUSKOKWIM DELTA. REGARDING MODEL UNCERTAINTY, THE GFS HAS BEEN THE
"MOST" CONSISTENT OVER ITS LAST FEW RUNS AND THE EC HAS BEEN
TRENDING TOWARDS THE GFS. THE NAM, ON THE OTHER HAND, CONTINUES TO
ALTERNATE SOLUTIONS THROUGH THE MEDIUM TERM. THIS FORECAST LEANS
INTO THE GFS/EC SOLUTION. THIS MEANS A RELATIVELY MORE IMPACTFUL
SYSTEM ARRIVING TO YUKON- KUSKOKWIM DELTA FROM MONDAY AFTERNOON
THROUGH TUESDAY MORNING. THE FETCH OF SOUTHWESTERLY WINDS
ASSOCIATED WITH THIS SYSTEM DOES NOT LOOK IMPRESSIVE, BUT WHAT IS
INTERESTING IS THAT MOST OF THE MODEL GUIDANCE WANTS TO CONTINUE
TO STEADILY DEEPEN THE LOW JUST AS IT MOVES INLAND, AND ALSO SHOWS
WESTERLY SMALL CRAFT WINDS ON THE BACKSIDE OF THE LOW SOMETIME ON
TUESDAY MORNING. THIS LAST MINUTE PUSH OF ONSHORE WINDS MAY BE
ENOUGH TO CAUSE MINOR WATER LEVEL RISES AND COASTAL EROSION FOR
LOCATIONS LIKE KIPNUK. THE PROBABILISTIC EXTRATROPICAL STORM SURGE
GUIDANCE ONLY BRINGS WATER LEVELS TO JUST ABOVE MHHW (MEAN HIGHER
HIGH WATER) TUESDAY MORNING. DUE TO THE FACT THAT ALMOST ALL OF
THE MODELS SHOW THE LOW STRENGTHENING ON ITS APPROACH TO THE
KUSKOKWIM BAY AREA, WE WILL CONTINUE TO CLOSELY MONITOR THIS
SYSTEM AND UPDATE THIS FORECAST AS MODEL AGREEMENT MATURES.
LONG TERM FORECAST (WEDNESDAY THROUGH SATURDAY)
A PROGRESSIVE PATTERN WILL BRING MORE SYSTEMS THROUGH THE REGION
FOR THE REST OF THE WEEK. A BERING LOW TRACKS INTO SOUTHWEST
ALASKA EARLY WEDNESDAY. WHILE THE MODEL QPF VALUES DO NOT SEEM
HIGH, THE SYNOPTIC SET UP SEEMS INDICATIVE FOR HEAVY RAIN IN
SOUTHCENTRAL. THERE IS ENHANCED UPPER LEVEL FLOW FROM A STRONG
RIDGE OVER THE NORTH PACIFIC AND AN UPPER LEVEL LOW OVER INTERIOR
ALASKA. THIS SOUTHERLY FLOW IS BRINGING MOISTURE FROM TROPICAL
LATITUDES. GIVEN THE SURFACE PRESSURE GRADIENT, THERE COULD BE
STRONG GAP WINDS THROUGH SOUTHCENTRAL AS WELL AS THE ALASKA
PENINSULA. THE EXACT TRACK OF THE LOW WILL DETERMINE WHETHER OR
NOT THERE WILL BE A STRONG TURNAGAIN OR KNIK ARM WIND DURING THIS
SYSTEM. THE UPPER LEVEL FLOW MENTIONED EARLIER WINDS DOWN BEFORE
THURSDAY FROM THE UPPER LEVEL RIDGE PROGRESSING EASTWARD, SHUTTING
DOWN ANY CHANCES OF HEAVY RAIN OR WINDS.
FOR THE REST OF THE WEEK, A WEAK TROUGH IN THE GULF WILL BRING
MOSTLY CLOUDY CONDITIONS WITH SHOWERS FOR SOUTHCENTRAL, SOUTHWEST,
AND THE ALASKA PENINSULA.
AN UPPER LEVEL KAMCHATKA LOW WILL ENTER THE BERING EARLY FRIDAY
AND FORM A BERING LOW. WEST OF ADAK COULD SEE RAIN AND WIND ON
FRIDAY. THE LOW IS EXPECTED TO STRENGTHEN THROUGH OUT SATURDAY AND
WILL CONTINUE TO MOVE EASTWARD. MODELS ARE NOT IN AGREEMENT WITH
THE EXACT TRACK OF THIS LOW GIVEN HOW FAR OUT IN TIME. THE SYSTEM
SHOULD BRING RAIN AND WINDIER CONDITIONS FOR THE REMAINDER OF THE
ALEUTIANS. IT IS IMPORTANT TO NOTE THAT THERE IS MINIMAL
CONFIDENCE OF CONDITIONS REACHING HAZARDOUS CRITERIA FOR ANY OF
THE ALEUTIANS.
-SS
AVIATION
PANC...PATCHY DENSE FOG HAS DEVELOPED NEAR THE TERMINAL THIS
MORNING, MOSTLY LOCALIZED TO THE LAKE HOOD AND ANCHORAGE
INTERNATIONAL VICINITY. EXPECT VISIBILITY AND CEILINGS TO VARY
FROM LIFR TO VFR AS THE PATCHY BUT DENSE FOG DRIFTS IN AND OUT OF
THE TERMINAL FOR THE NEXT FEW HOURS. THE FOG WILL BEGIN TO BURN
OFF BY THE LATE MORNING HOURS AS VFR CONDITIONS QUICKLY RETURN.
FOG POTENTIAL LOOKS TO BE LOWER TONIGHT INTO MONDAY MORNING WITH
MORE CLOUD COVER BEING PRESENT.
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