103
FXAK68 PAFC 251345
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
545 AM AKDT MON OCT 25 2021
ANALYSIS AND UPPER LEVELS
A COMPACT LOW CENTERED SOUTH OF SEWARD IS SPREADING LIGHT
RAIN/SPRINKLES ACROSS THE EASTERN KENAI PENINSULA. A NARROW BAND
OF SOMEWHAT HEAVIER RAIN IS MOVING NEAR SEWARD. ELSEWHERE, NEARLY
ALL OF SOUTHCENTRAL AND SOUTHWEST ALASKA IS QUIET WITH WEAK HIGH
PRESSURE OVER THE AREA. UNLIKE THE PRECIPITATION, THE CLOUD COVER
IS QUITE EXTENSIVE OVER MUCH OF SOUTHERN ALASKA, WITH LOW CLOUDS
AND EVEN A BIT OF LIGHT SNOW OVER THE LOWER KUSKOKWIM VALLEY, AND
CLOUD COVER FROM THE GULF LOW SPREADING NORTH OVER MUCH OF
SOUTHCENTRAL. A STORM FORCE LOW THAT TRACKED ALONG THE ALEUTIAN
CHAIN YESTERDAY IS BEGINNING TO MAKE ITS EXIT BACK INTO THE NORTH
PACIFIC SOUTH OF THE AKPEN.
IN THE UPPER LEVELS, THE FLOW REMAINS LARGELY CHAOTIC OVER MUCH OF
SOUTHERN MAINLAND ALASKA, THOUGH ON AVERAGE, THE UPPER LEVEL FLOW
IS ABOUT 10 TO 20 KTS OUT OF THE SOUTH IN THE MID-LEVELS. THE
SUBTROPICAL PACIFIC JET IS NOW ZONAL AND IS CENTERED SOUTH OF 50N,
AND THEREFORE REALLY NOT IMPACTING THE STATE AT ALL THIS MORNING.
MODEL DISCUSSION
MODEL AGREEMENT IS GOOD ON THE LARGE SCALE THIS MORNING. FOR THE
MOST PART, THE WEATHER REMAINS QUIET OVER NEARLY ALL OF THE AREA.
THE STORM FORCE LOW WHICH TRACKED THE LENGTH OF THE ALEUTIAN CHAIN
YESTERDAY IS NOW MOVING SOUTH OF ALASKA AS IT HEADS SOUTH OF THE
GULF. IT WILL MOVE INTO THE PANHANDLE TUESDAY, AT WHICH POINT IT
MAY DRIFT BACK WESTWARD AS IT WEAKENS, WHICH MAY CAUSE SOME
PRECIPITATION ALONG THE COAST TO PRINCE WILLIAM SOUND BY
WEDNESDAY. THERE ARE SOME TIMING DIFFERENCES WITH A WEAK LOW
APPROACHING THE KUSKOKWIM DELTA TUESDAY EVENING, BUT IMPACTS FROM
THIS LOW REGARDLESS WERE MINIMAL. FORECAST CONFIDENCE IS HIGH.
AVIATION
PANC...VFR CONDITIONS AND LIGHT WINDS WILL PERSIST.
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 2:
MONDAY THROUGH TUESDAY NIGHT)...
LOW PRESSURE OVER THE GULF IS WEAKENING THIS MORNING WHILE
SUSTAINING LIGHT SHOWERS OVER PRINCE WILLIAM SOUND AND PORTIONS OF
THE KENAI PENINSULA. THIS LOW WILL EVENTUALLY LIFT NORTHWARD INTO
SOUTHCENTRAL ON TUESDAY AND DISSIPATE. HOWEVER, LINGERING SHOWERS
MAY PERSIST THROUGH THE MORNING HOURS ON MONDAY FOR PORTIONS OF
KODIAK WHILE OFF AND ON RAIN MAY PERSIST INTO THE OVERNIGHT HOURS
FOR CORDOVA. ANY ADDITIONAL AREAS OF PRECIPITATION WILL GRADUALLY
CLEAR OUT WITH PARTLY CLOUDY SKIES FOR MUCH OF THE DAY THROUGHOUT
SOUTHCENTRAL. MOSTLY BENIGN CONDITIONS ARE FORECAST THE NEXT
COUPLE OF DAYS WITH A LACK OF ANY SIGNIFICANT AREAS OF FORCING OR
TROUGH MOVEMENT THROUGH THE REGION. THE ARRIVAL OF COLDER AIR
FILTERING IN FROM THE NORTH AND NORTHWEST IS ANTICIPATED ON
TUESDAY AND TUESDAY NIGHT WITH A FEW FLURRIES POSSIBLE FOR THE
ANCHORAGE BOWL EARLY ON WEDNESDAY. LIGHT SNOW WILL ALSO BE
POSSIBLE ACROSS THE TALKEETNAS INTO THE COPPER BASIN WITH
NEGLIGIBLE ACCUMULATIONS. OTHERWISE, THE COLDER UPPER TEMPERATURES
ARE FORECAST TO BRING INCREASINGLY GUSTY WINDS TO OUTFLOW PRONE
REGIONS ALONG THE COAST, INCLUDING WEST AND EAST OF THE BARREN
ISLANDS, ACROSS SEWARD AND RESURRECTION BAY, VALDEZ PORT, AS WELL
AS THOMPSON PASS BY THE MIDDLE OF THE WEEK.
SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 TO 2)
A GENERALLY QUIET PATTERN IS IN TRACK TO CONTINUE OVER THE COURSE
OF THE NEXT COUPLE DAYS. COOL NORTHERLY FLOW WILL CONTINUE EAST
OF A SHORTWAVE RIDGE CENTERED OVER THE BERING, KEEPING CONDITIONS
DRY BY AND LARGE WITH PARTLY CLOUDY SKIES THROUGH TUESDAY.
OCCASIONAL SNOW SHOWERS ARE POSSIBLE NEAR THE KUSKOKWIM DELTA
COAST AS THEY MOVE ONSHORE FROM THE BERING WITH WEAK WAVES PASSING
THROUGH ALOFT. TEMPERATURES ARE SEASONABLY COOL, WITH HIGHS
AROUND THE FREEZING MARK TODAY AND TUESDAY AND INLAND LOWS DIPPING
INTO THE 10S FOR MOST AREAS FOR EARLY TUESDAY AND WEDNESDAY
MORNINGS.
ON TUESDAY AFTERNOON, A LOW MOVING OFF OF KAMCHATKA WILL ENTER THE
NORTHERN BERING AND DROP SOUTH BETWEEN THE PRIBILOFS AND NUNIVAK
ISLAND BY WEDNESDAY MORNING. THIS SHOULD BRING A FRONT ONSHORE AT
SOME POINT ALONG THE SOUTHWEST COAST, ALTHOUGH MODELS VARY
SOMEWHAT WITH THE PROGRESSION OF BOTH THE FRONT AND ITS PARENT
LOW BY THIS POINT IN TIME. THE FASTER SOLUTIONS BRING A BAND OF
POTENTIALLY MODERATE SNOWFALL INTO PARTS OF THE Y-K DELTA AND
NORTHERN BRISTOL BAY BY AROUND MIDDAY WEDNESDAY, WITH SLOWER
SOLUTIONS KEEPING FRONTAL PRECIP LIMITED TO COASTAL LOCATIONS
UNTIL LATER IN THE DAY. THE CURRENT FORECAST REFLECTS A MIDDLE
GROUND SOLUTION, WITH SNOWFALL SPREADING SLOWLY INLAND FROM WEST
TO EAST ON WEDNESDAY MORNING.
SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 TO 2)
A NORTH PACIFIC LOW SOUTH OF THE ALASKA PENINSULA THIS MORNING
WILL EXIT THE PICTURE BY THIS AFTERNOON AS IT MOVES OUT TOWARDS
THE GULF, WITH EASTERLY GALE FORCE WINDS ALONG AND SOUTH OF THE
EASTERN ALEUTIANS QUICKLY SUBSIDING. A HIGH PRESSURE RIDGE WILL
MOVE OVER THE BERING IN ITS PLACE FROM TONIGHT INTO TUESDAY,
YIELDING A SHORT BREAK IN THE ACTIVE WEATHER FOR MUCH OF THE
REGION. GAP WINDS ON TUESDAY WILL PICK UP THROUGH THE SOUTHERN
AKPEN AS NORTHERLY FLOW STRENGTHENS BETWEEN THE BERING RIDGE AND
LOW MOVING SOUTH OF THE GULF. WIDELY SCATTERED CONVECTIVE RAIN AND
SNOW SHOWERS WILL CONTINUE OVER MUCH OF THE BERING AS COLD AIR
ADVECTING OVER THE SEA SURFACE PICKS UP MOISTURE AND WARMTH AND
BECOMES UNSTABLE NEAR SEA LEVEL.
A KAMCHATKA LOW WILL DROP SOUTH INTO THE NORTHERN BERING LATE ON
TUESDAY, BRINGING ANOTHER ROUND OF MORE ACTIVE WEATHER BACK INTO
PLAY. GALES ARE NOW ANTICIPATED TO WRAP AROUND THE WESTERN SIDE OF
THE SYSTEM, SPREADING SOUTH TOWARDS THE PRIBILOFS ON WEDNESDAY
MORNING. A SWIFTLY MOVING BAND OF MOSTLY RAIN MIXING WITH SNOW
WILL MOVE OUT AHEAD OF THE LOW ALONG ITS FRONT, PASSING OVER THE
PRIBILOFS TUESDAY NIGHT AND MOVING SOUTHEAST INTO THE ALEUTIANS BY
EARLY WEDNESDAY MORNING.
MARINE (DAYS 3 THROUGH 5: WEDNESDAY THROUGH FRIDAY)
CONFIDENCE IS HIGH WITH A BENIGN PATTERN SETTING UP FOR THE GULF
OF ALASKA WATERS THROUGH FRIDAY. WEAK LOW PRESSURE WILL DEVELOP
NEAR PRINCE WILLIAM SOUND WEDNESDAY NIGHT BEFORE MOVING OVER
CANADA. THURSDAY NIGHT AND INTO FRIDAY, LOW PRESSURE WILL TRACK
NEAR KODIAK. AN ATTENDANT FRONT WILL MOVE NORTH, POTENTIALLY
CREATING A GALE FORCE BARRIER JET FRIDAY EVENING.
A SIBERIAN LOW WILL MOVE INTO THE NORTHERN BERING WEDNESDAY. THIS
LOW WILL DEEPEN AS IT MOVES TOWARDS BRISTOL BAY THURSDAY,
PROVIDING LOW END GALES, WITH HIGHER END GALES POSSIBLE. LOW
PRESSURE DEVELOPING OFF OF THE COAST OF JAPAN EARLY THIS WEEK WILL
MOVE NORTH TOWARDS THE ALEUTIAN WATERS. CONFIDENCE REMAINS LOW ON
THE FORECAST TRACK. PRESENTLY IT REMAINS SOUTH OF THE FORECAST
MARINE AREA.
.LONG TERM DISCUSSION (DAYS 4 THROUGH 7: THURSDAY THROUGH
SUNDAY)...
LOW PRESSURE THAT IS DEVELOPING NEAR JAPAN WILL BE THE PRIMARY
WEATHER MAKER INTO THE LONG TERM FORECAST. THE FORECAST CHALLENGES
FOR THE ALEUTIANS WILL BE HOW FAR NORTH THIS LOW MOVES. AMERICAN
GUIDANCE LIFTS IT CLEAR ACROSS ADAK, WHILE EUROPEAN GUIDANCE KEEPS
IT A FEW HUNDRED NAUTICAL MILES SOUTH. BY THE WEEKEND, THE
PICTURE DOES GET A LITTLE CLEARER AS A FRONT WILL LIFT NORTH
ACROSS THE GULF OF ALASKA AND IMPACT THE COAST OF SOUTH CENTRAL
AND KODIAK. FOR COASTAL AREAS FACING THE GULF AND INLAND AREAS
NEAR COOK INLET, FREEZING LEVELS ARE PROGGED TO BE IN THE 2.5 TO 3
KFT RANGE, KEEPING COLD RAIN IN THE FORECAST FROM HOMER THROUGH
PALMER. MEANWHILE THE CHUGACH AND PARTS OF THE ALASKA, TALKEETNA
AND WRANGELL RANGES WILL SEE SNOW ABOVE. TEMPERATURES ARE NOT
EXPECTED TO DEVIATE MUCH FROM NORMAL FOR THIS TIME OF YEAR.
AFC WATCHES/WARNINGS/ADVISORIES
PUBLIC...NONE.
MARINE...GALE WARNING: 130 131 138 150.
SYNOPSIS AND MODEL DISCUSSION...JPW
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...AS
MARINE/LONG TERM...SS
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