331
FXAK68 PAFC 010054
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
454 PM AKDT SAT MAY 31 2025
SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3)
DISCUSSION:
A WEAKENING SURFACE TROUGH OVER PRINCE WILLIAM SOUND AND
ASSOCIATED UPPER-LEVEL TROUGH CONTINUE TO SLOWLY MOVE OFF TO THE
EAST THIS AFTERNOON. LINGERING MOISTURE, SURFACE HEATING FROM
BREAKS IN THE CLOUDS THIS MORNING, AND LIFT FROM THE TROUGH, HAVE
ALL ALLOWED SCATTERED SHOWERS TO REDEVELOP ALONG THE FOOTHILLS OF
THE THE KENAI, CHUGACH, AND TALKEETNA MOUNTAINS. THESE SHOWERS ARE
DRIFTING SLOWLY NORTHWARD, TRAINING NEAR HOPE, ALONG THE ANCHORAGE
HILLSIDE, AND FROM WILLOW TO TALKEETNA. THE INCREASED SHOWER
ACTIVITY SHOULD WIND DOWN THROUGH THE EVENING HOURS AS
TEMPERATURES COOL AND THE TROUGH EXITS THE REGION.
SIMILAR CONDITIONS ARE ALSO TAKING PLACE ACROSS EASTERN PRINCE
WILLIAM SOUND AND THE COPPER BASIN, WITH THE BULK OF THE SHOWERS
FIRING UP ALONG THE SOUTHERN FACING SLOPES OF THE MOUNTAINS IN
UPSLOPE FLOW. TEMPERATURES ACROSS SOUTHCENTRAL HAVE PUSHED INTO
THE MID 50S FOR MOST LOCATIONS, ESPECIALLY AWAY FROM THE IMMEDIATE
COAST, DUE TO THE DIMINISHING CLOUD COVER AND BREAKS OF SUN.
THE NEXT FEATURE OF NOTE IS A ELONGATED LOW THAT IS DROPPING
SOUTHWARDS INTO THE BERING SEA. THIS LOW WILL CONTINUE TO DEEPEN
OVER THE BERING THIS WEEKEND AS A SECONDARY LOW DROPS SOUTH AND
MERGES WITH THE PRIMARY LOW BY SUNDAY. MODEST SOUTHWESTERLY FLOW
ALONG OF THIS SYSTEM (ALSO NOTED WELL IN WATER VAPOR IMAGERY) WILL
PULL A GOOD FETCH OF MOISTURE NORTH. AS THE ASSOCIATED FRONT LIFTS
ACROSS THE WESTERN GULF, MODERATE TO HEAVY RAIN WILL SET-UP ALONG
THE EASTERN ALASKA PENINSULA, KODIAK ISLAND, AND EASTERN KENAI
PENINSULA. IN ADDITION TO HEAVY RAINFALL, WINDS WILL INCREASE ALONG
THE FRONT WITH GALES AND POSSIBLY STORM FORCE WINDS DEVELOPING OVER
THE WESTERN GULF...INCLUDING THE BARREN ISLANDS AND KAMISHAK BAY
AREAS. CROSS-BARRIER FLOW WILL SET-UP OVER THE KENAI AND CHUGACH
MOUNTAINS HELPING TO DOWNSLOPE THE WESTERN KENAI PENINSULA,
ANCHORAGE BOWL, AND MAT VALLEY. FOR THESE AREAS, LITTLE TO NO
RAINFALL IS ANTICIPATED, BUT GUSTY WINDS ARE LIKELY BY SUNDAY
AFTERNOON AS THE GRADIENT TIGHTENS OVER THE MOUNTAINS AND GAP
WINDS TURN SOUTHERLY ONCE AGAIN.
PRECIPITATION LINGERS THROUGH MONDAY AS THE FRONT STALLS OVER
PRINCE WILLIAM SOUND. GAP WINDS WILL ALSO PERSIST, BUT WILL LIKELY
BE NOT QUITE AS STRONG AS THE WINDS SUNDAY DUE TO A SLIGHTLY
WEAKER PRESSURE GRADIENT AS THE FRONT BEGINS TO FALL APART.
ANOTHER ROUND OF RAIN ARRIVES FOR TUESDAY. MEASURABLE RAINFALL IS
LIKELY FOR INTERIOR LOCATIONS WITH THIS SYSTEM AS THE
SOUTHWESTERLY CROSS-BARRIER FLOW FROM THE PREVIOUS SYSTEM WEAKENS
AND BECOMES SOUTHWESTERLY.
- PP/TM
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (DAYS
1 THROUGH 3: TODAY THROUGH TUESDAY AFTERNOON)...
A STRONG NORTH PACIFIC LOW PRESSURE SYSTEM TRACKING ACROSS THE
EASTERN ALEUTIANS THIS AFTERNOON CONTINUES TO DEEPEN AS IT TRACKS
NORTHWARDS INTO THE BERING SEA. PERSISTENT RAINFALL AND GALE-FORCE
WINDS WITH THE POTENTIAL FOR STORM-FORCE GUSTS WILL CONTINUE THIS
AFTERNOON THROUGH SUNDAY MORNING ACROSS THE ALASKA PENINSULA AS
THE SYSTEM CONTINUES TO PHASE WITH THE DECAYING LOW IN THE CENTRAL
BERING. THE STRONGEST CORE OF WINDS WILL REACH THE SOUTHWEST
COAST TONIGHT AND PERSIST THROUGH THE MORNING HOURS ON SUNDAY,
BRINGING ONSHORE GALE- FORCE WINDS WITH STORM-FORCE GUSTS
POSSIBLE. A COASTAL FLOOD ADVISORY FOR THE KUSKOKWIM DELTA COAST
INCLUDING KWIGILLINGOK, KONGIGANAK, AND KIPNUK REMAINS IN EFFECT
THROUGH 9 PM SUNDAY NIGHT AS THESE STRONG ONSHORE WINDS IN
COMBINATION WITH HIGH TIDES ARE EXPECTED TO RESULT IN WATER LEVELS
1.5 TO 2.5 FEET ABOVE THE NORMAL HIGHEST TIDE LINE. LIGHT RAIN
SPREADS INLAND WITH THE FRONT BY SUNDAY MORNING, SLOWLY WEAKENING
THROUGHOUT THE DAY.
A POTENT UPPER-LEVEL SHORTWAVE DROPPING DOWN ON THE BACK SIDE OF
THE LOW WILL SPREAD RAIN SHOWERS AND GUSTY WINDS WEST TO EAST
ACROSS THE ALEUTIAN CHAIN THROUGH TOMORROW NIGHT. BY MONDAY, THE
LOW CENTER TRACKS INTO THE EASTERN BERING SEA AND BRINGS ANOTHER
ROUND OF ENHANCED SOUTHEASTERLY WINDS AND RAINFALL TO SOUTHWEST
ALASKA BEHIND THE INITIAL FRONT. FOR THE KUSKOKWIM DELTA COAST,
ELEVATED WATER LEVELS ARE AGAIN POSSIBLE DURING HIGH TIDE MONDAY,
BUT SHOULD REMAIN BELOW LEVELS OF PREVIOUS HIGH TIDE CYCLES DUE TO
WEAKER WINDS AND LOWER TIDE HEIGHT. UNSETTLED AND SHOWERY WEATHER
CONTINUES ACROSS THE ALASKA PENINSULA AND SOUTHWEST ALASKA
THROUGH TUESDAY MORNING AS THE LOW WEAKENS AND BECOMES QUASI-
STATIONARY NEAR THE SOUTHWEST ALASKA COAST.
.LONG TERM FORECAST (DAYS 4 THROUGH 7: WEDNESDAY THROUGH
SATURDAY)...
GENERAL UPPER LEVEL LONGWAVE TROUGHING ACROSS THE SOUTHWEST AND
ALEUTIANS WILL CONTINUE THROUGH THE LONG TERM. THIS FEATURE, ALONG
WITH EMBEDDED ROTATING SHORTWAVES, WILL CONTINUE TO SUPPORT
COOLER AND WETTER THAN AVERAGE WEATHER CONDITIONS FOR MUCH OF THE
STATE AS WAVES OF SURFACE LOW PRESSURE MOVE ACROSS THE REGION.
DETERMINISTIC AND ENSEMBLE GUIDANCE SUGGEST TWO ROUNDS OF
PRECIPITATION WILL IMPACT SOUTHCENTRAL WITH A TROUGH MOVING
ONSHORE OF THE GULF COAST ON TUESDAY AND A SECOND TROUGH TO LIFT
THROUGH THE REGION ON WEDNESDAY. THIS WILL HELP TO MAINTAIN COOLER
TEMPERATURES AND KEEP RAIN CHANCES IN THE FORECAST FOR
SOUTHCENTRAL. A BREAK FROM PRECIPITATION MAY THEN DEVELOP ON
THURSDAY AND MORE LIKELY FRIDAY FOR THE REGION BETWEEN SYSTEMS,
THOUGH ANY CLEARING WILL PRESENT A CHANCE FOR AFTERNOON
THUNDERSTORMS.
-AM/BL
AVIATION
PANC...VFR WILL GENERALLY PERSIST THROUGH THE TAF PERIOD.
SCATTERED SHOWERS WILL CONTINUE ACROSS THE AREA TODAY AND WILL
GRADUALLY DISSIPATE WITH THE LOSS OF HEATING THIS EVENING. WIND
WILL GRADUALLY INCREASE TODAY AND THEN BECOME GUSTY OUT OF THE
SOUTHEAST / TURNAGAIN ARM THIS EVENING. DOWN-INLET PRESSURE
GRADIENT SHOULD RESULT IN NORTHERLY FLOW LATE OVERNIGHT INTO
TOMORROW MORNING, BUT THERE DOES REMAIN A CHANCE WIND REMAINS
SOUTHEAST. WIND WILL INCREASE IN STRENGTH TOMORROW, PARTICULARLY
IN THE AFTERNOON WITH THE APPROACH OF A FRONT AND IN RESPONSE TO
INLAND HEATING.
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