087
FXAK68 PAFC 170222
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
622 PM AKDT WED SEP 16 2026
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3:
THIS AFTERNOON THROUGH SATURDAY AFTERNOON)...
KEY MESSAGES:
- UNSETTLED BUT LESS STORMY WEATHER THROUGH TOMORROW. THEN, WETTER
CONDITIONS RETURN FROM FRIDAY INTO THE WEEKEND AS TWO STORMS
MOVE NORTH ACROSS THE GULF AND INTO SOUTHCENTRAL.
- TRENDING COLDER, WITH OVERNIGHT LOWS DIPPING INTO THE LOW 40S TO
LOW 30S BY FRIDAY NIGHT/SATURDAY MORNING.
DISCUSSION:
WITH THE LOW THAT BROUGHT OUR STORMY WEATHER NOW WEAKENING AS IT
EXITS INTO NORTHERN ALASKA, CONDITIONS ARE GENERALLY IMPROVING.
THE HIGHEST RECORDED WINDS TODAY WERE A PEAK GUST OF 43 MPH AT THE
PORT OF ANCHORAGE, AND 53 MPH IN KENAI. THE WIND ADVISORIES WERE
EXPIRED AS WINDS ARE VERY UNLIKELY TO GUST TO 50 MPH OR GREATER;
HOWEVER, BREEZY CONDITIONS WILL LINGER THROUGH TONIGHT AS WINDS
WILL BE SLOW TO DIMINISH.
IN ADDITION TO WINDS, THE LOW ALSO BROUGHT SOME IMPRESSIVE
RAINFALL AMOUNTS. NOT MUCH RAIN HAS FALLEN SINCE THIS MORNING'S
FORECAST DISCUSSION, SO THE RAIN AMOUNTS REPORTED THEN REMAIN
VALID AND ARE REPEATED HERE: 1" FOR ANCHORAGE, NEAR 2" FOR
TALKEETNA, AND OVER 2" FOR CORDOVA. FOR ANCHORAGE, THE 1.16" OF
RAIN RECORDED YESTERDAY IS A NEW DAILY RECORD, BREAKING THE OLD
RECORD OF 0.94" SET IN 2015. MOREOVER, IT WAS THE 11TH WETTEST DAY
IN SEPTEMBER AND THE WETTEST SEPTEMBER DAY SINCE SEPTEMBER 29TH,
2015.
A WEAK, TRANSIENT RIDGE KEEPS OUR WEATHER MORE BENIGN THROUGH
TOMORROW MORNING. THEN, A SERIES OF SHORTWAVES AND AN INCOMING
UPPER LOW BRING INCREASED RAIN CHANCES INTO THE WEEKEND AS THEY
MOVE OVER SOUTHCENTRAL. RAIN WILL INITIALLY BE FOCUSED ALONG THE
COAST AS THE SHORTWAVES MOVE IN TOMORROW, THEN BECOME MORE
WIDESPREAD AS ANOTHER LOW MOVES FROM THE BERING SEA INTO
SOUTHWEST ALASKA. CONFIDENCE IS INCREASING THAT THE SHORTWAVE
TROUGH ASSOCIATED WITH THIS SYSTEM BECOMES NEGATIVELY TILTED AS IT
MOVES SOUTH ACROSS THE ALASKA PENINSULA. THIS EVOLUTION SUPPORTS
A DEVELOPING SOUTHEASTERLY WIND FLOW ALOFT OUT AHEAD OF THE TROUGH
WITH A SHORTWAVE UPSTREAM MOVING NORTH TOWARD THE KENAI PENINSULA
AND A SURFACE LOW MOVING INTO THE EASTERN PRINCE WILLIAM
SOUND/CAPE SUCKLING AREA BY FRIDAY MORNING. THIS SOLUTION RESULTS
IN A HIGH LIKELIHOOD (70-80%) OF RAIN SHOWERS SPREAD ACROSS MOST
OF THE SOUTHCENTRAL MAINLAND LATE TOMORROW INTO FRIDAY.
LOOKING AHEAD: A MUCH STORMIER WEEKEND IS IN STORE AS A STRONG
SHORTWAVE AND A BROAD LOW MOVE UP FROM THE GULF AND TOWARDS
SOUTHCENTRAL ON SATURDAY. MODELS ARE CONVERGING ON A CENTRAL
PRESSURE OF 975 TO 985 MB FOR THIS LOW, WITH WINDS TO GALE FORCE.
RAIN AMOUNT AND INTENSITY WILL ALSO BE SOMETHING TO WATCH, AS THE
NORTH GULF COAST (INCLUDING PRINCE WILLIAM SOUND AND EASTERN KENAI
PENINSULA) COULD SEE A LONG DURATION OF MODERATE RAIN.
-TM/KC
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS
(DAYS 1 THROUGH 3)...
KEY MESSAGES:
* A WEAK LOW MOVES THROUGH THE BERING SEA BRINGING WEAKER WINDS
AND PRECIPITATION TO THE SOUTHWEST ALASKA COAST WEDNESDAY AND
THURSDAY.
* A MORE POTENT ARCTIC FRONT BRINGS NORTHERLY WINDS THROUGH THE
ALEUTIANS LATE THIS WEEK INTO THE WEEKEND.
DISCUSSION:
A WEAK LOW MOVES ACROSS THE BERING SEA NORTH OF THE PRIBILOF
ISLANDS THROUGH TOMORROW MORNING BRINGING A RETURN TO
SOUTHWESTERLY WINDS TO THE ALEUTIANS, AK PEN AND THE SOUTHWESTERN
ALASKA COASTLINE. THESE WINDS WILL RANGE FROM 30 TO 40 MPH THIS
EVENING THROUGH EARLY THURSDAY MORNING WITH A 70% CHANCE OF
EXCEEDING 35 MPH THOUGH ONLY A 10% CHANCE OF EXCEEDING 40 MPH
DURING THIS TIME FRAME. THE STRONGEST OF THESE WINDS ARE LIKELY
LATE THIS EVENING INTO THE OVERNIGHT HOURS.
THROUGH THE DAY FRIDAY, A TROUGH MOVES ACROSS THE ALEUTIANS
BRINGING NORTHERLY WINDS AND FREQUENT RAIN SHOWERS IN ITS WAKE.
SIMULTANEOUSLY, A WEAK LOW IS SIGNALED TO FORM IN THE NORTH
PACIFIC FROM ADAK TO UNALASKA. THIS LOW MOVES THROUGH THE NORTH
PACIFIC AND INTO THE GULF OF ALASKA EARLY THIS WEEKEND. AS IT
STRENGTHENS THROUGH SATURDAY, THE SPEED OF THE NORTHERLY WINDS
THROUGH ALEUTIAN GAPS AND PASSES WILL INCREASE. FRIDAY EVENING
THROUGH SATURDAY AFTERNOON. A 40% CHANCE OF WIND GUSTS EXCEEDING
40 MPH IN THE CENTRAL ALEUTIANS TO THE ALASKA PENINSULA (AK PEN)
FRIDAY MORNING INTENSIFIES TO A 40% CHANCE OF WIND GUSTS EXCEEDING
55 MPH BY SATURDAY MORNING; STRONGEST IN THE EASTERN ALEUTIANS AT
THIS TIME.
LONG TERM FORECAST (DAYS 4 TO 7, SUNDAY THROUGH WEDNESDAY)
BY SUNDAY MORNING, HEAVY RAINFALL WILL BE ONGOING FOR THE
NORTHERN GULF COAST AND SMALL-CRAFT TO GALE FORCE WINDS WILL BE
PRESENT THROUGHOUT THE GULF AROUND AN OCCLUDING LOW. FURTHER AWAY
FROM THE LOW, LIGHTER SHOWERS ARE LIKELY ACROSS THE WESTERN
SUSITNA VALLEY AND PORTIONS OF THE AKPEN, WITH MORE ISOLATED
SHOWERS ACROSS THE REST OF SOUTHCENTRAL AND SOUTHWEST. WITH STRONG
COLD AIR ADVECTION BEHIND THE LOW, SNOW LEVELS WILL HAVE DROPPED
TO AROUND 2000 FEET ACROSS SOUTHWEST ALASKA AND THE AKPEN AND
AROUND 4000-4500 FEET ACROSS SOUTHCENTRAL BY SUNDAY MORNING. AT
HIGHER ELEVATIONS, ESPECIALLY ACROSS SOUTHWEST ALASKA,
PRECIPITATION SUNDAY AND ONWARDS LIKELY FALLS AS SNOW. IN THE
EASTERN BERING THROUGH THE ALEUTIANS AND AKPEN, NORTHWESTERLY
WINDS UP TO SMALL-CRAFT FORCE ARE LIKELY ONGOING SUNDAY MORNING
DUE TO COLD AIR ADVECTION ON THE WEST SIDE OF THE LOW.
WHILE THE UPPER LEVEL LOW REMAINS OVER THE GULF, THE SURFACE LOW
LOOKS TO MOVE INTO THE COAST BY SUNDAY AFTERNOON AND RAPIDLY
WEAKEN ONCE ONSHORE. WINDS SIGNIFICANTLY DECREASE SUNDAY NIGHT
AROUND THE GULF AS THE PRESSURE GRADIENT WEAKENS. EVEN AS THE LOW
WEAKENS, NORTHWESTERLY GAP WINDS WILL PERSIST THROUGH THE AKPEN
AND EASTERN ALEUTIANS. THOUGH IT APPEARS THE STRONGEST WINDS WILL
BE SATURDAY INTO SUNDAY, CONSTANT COLD AIR ADVECTION WILL ALLOW
NORTHWEST WINDS TO PERSIST AT OR NEAR SMALL-CRAFT FORCE THROUGH
MONDAY EVENING. WITH THE WEAKENING LOW, SHOWERS SHOULD TAPER OFF
FOR SOUTHWEST ALASKA BY MONDAY AFTERNOON. DUE TO WINDS UPSLOPING
IN THE AKPEN, SHOWERS LIKELY PERSIST THERE THROUGH TUESDAY. GIVEN
CONTINUOUS COLD AIR ADVECTION, SNOW LEVELS DROP FURTHER ON MONDAY
TO AROUND 1000 FEET ACROSS SOUTHWEST, 1500-2000 FEET IN THE AKPEN.
PLACES ABOVE ELEVATIONS MENTIONED WILL LIKELY RECEIVE SOME
SNOWFALL, ESPECIALLY IF PRECIPITATION PERSISTS INTO MONDAY. SINCE
SOUTHCENTRAL IS CLOSER TO THE LOW, PRECIPITATION WILL PERSIST
THERE LONGER. THE HEAVIEST PRECIPITATION WILL BE SUNDAY INTO
MONDAY MORNING ALONG THE NORTHERN GULF COAST WITH LIGHTER
PRECIPITATION INLAND AS THE LOW MOVES ONSHORE. THIS MEANS RAIN
BELOW 4000 FEET AND SNOW ABOVE 4000-5000 FEET. WITH THE LOW
WEAKENING, PRECIPITATION SHOULD SLOWLY TAPER OFF AT LOWER
ELEVATIONS BY MONDAY AFTERNOON WHILE PERSISTING AT HIGHER
ELEVATIONS THROUGH TUESDAY MORNING. COLD AIR ADVECTION BEGINS TO
DROP SNOW LEVELS MONDAY TO AROUND 2500-3500 FEET. FOR PLACES ABOVE
2500-3500 FEET, ANY PRECIPITATION THAT LINGERS MONDAY AND ONWARDS
LIKELY FALLS AS SNOW. ADDITIONALLY, BELOW AVERAGE TEMPERATURES
WILL ALLOW FOR MANY PLACES ACROSS SOUTHWEST AND SOUTHCENTRAL TO
DROP BELOW FREEZING FOR THIS FIRST TIME THIS FALL.
TROUGHING LOOKS TO PERSIST ACROSS MAINLAND ALASKA THROUGH TUESDAY
AS THE UPPER LOW REMAINS STATIONARY OVER THE GULF. REMNANTS OF
THE SURFACE LOW SHOULD MOVE AWAY FROM SOUTHCENTRAL BY TUESDAY
AFTERNOON, TAPERING OFF ANY LINGERING PRECIPITATION ALONG THE
COAST. MEAN ENSEMBLES SHOW ANOTHER POTENTIAL LOW ENTERING THE
WESTERN BERING AND WESTERN ALEUTIANS TUESDAY INTO WEDNESDAY, WHICH
MAY BRING MORE RAIN AND WIND THERE. THERE ALSO IS SOME POTENTIAL
FOR POST-TROPICAL ACTIVITY TO MAKE ITS WAY TO THE WESTERN
ALEUTIANS BETWEEN TUESDAY-WEDNESDAY. CONFIDENCE WITH EITHER
SOLUTION IS CURRENTLY LOW, AND DETAILS WILL BECOME MORE CLEAR IN
THE COMING DAYS. OTHERWISE CONDITIONS LOOK TO BE RELATIVELY
BENIGN ACROSS MOST SOUTHERN ALASKA TUESDAY INTO WEDNESDAY.
- PA
AVIATION
PANC...GUSTY SOUTH WINDS WILL GRADUALLY DIMINISH THROUGH THIS
EVENING, BUT REMAIN SOUTHERLY WITH GUSTS UP TO 15 OR 20 KTS
THROUGH THURSDAY. VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD,
THOUGH CEILINGS COULD LOWER TO AROUND 4,000 FT THURSDAY MORNING
WITH LIGHT RAIN SHOWERS DEVELOPING AROUND THE AREA.
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