109
FXAK68 PAFC 311254
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
454 AM AKDT SAT MAY 31 2025
SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3)
DISCUSSION:
SEVERAL FEATURES SHOWING UP NICELY ON WATER VAPOR IMAGERY THIS
MORNING. THE FIRST OF THESE IS A COMPACT LOW THAT IS NOW MOVING INTO
PRINCE WILLIAM SOUND. ON THE BACKSIDE OF THIS LOW, A LINE OF
SCATTERED SHOWERS HAS REDEVELOPED FROM THE SEWARD NORTH TO THE
TOWARDS THE TALKEETNA MOUNTAINS AND EASTERN SUSITNA VALLEY. THE
SHOWERS ARE EXPECTED TO WIND DOWN LATER THIS MORNING AS THE LOW
CONTINUES TO MOVE OUT OF THE AREA. HOWEVER, DEPENDING ON THE AMOUNT
OF CLEARING THIS AFTERNOON, COULD SEE DIURNALLY DRIVEN SHOWERS
DEVELOP ALONG THE WESTERN SIDE OF THE CHUGACH AND TALKEETNA
MOUNTAINS, AND POSSIBLY SOME ISOLATED STORMS IN THE SUSITNA AND
COPPER RIVER VALLEY. TEMPERATURES WILL START OUT COOL TODAY BUT WITH
SHORTWAVE RIDGING MOVING IN AND MODEST CLEARING FOR MANY AREAS,
TEMPERATURES SHOULD REBOUND BY THIS AFTERNOON.
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 AS THE GRADIENT
TIGHTENS OVER THE MOUNTAINS.
- PP
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (DAYS
1 THROUGH 3: TODAY THROUGH MONDAY NIGHT)...
A BROAD LOW PRESSURE SYSTEM OVER THE BERING SEA CONTINUES TO
BRING WIDESPREAD RAIN AND ENHANCED SOUTHERLY WINDS TO THE CENTRAL
AND EASTERN BERING SEA. A STRONG NORTH PACIFIC LOW IS CURRENTLY
LIFTING UP TOWARD THE BERING SEA, AND WILL BRING MODERATE TO HEAVY
PRECIPITATION AND GALE FORCE WINDS TO THE EASTERN
ALEUTIANS/BERING SEA AND ALASKA PENINSULA THROUGH THE WEEKEND.
ENERGY FROM THIS SYSTEM PHASES WITH THE BERING LOW, PUSHING HIGH-
END GALE FORCE SOUTHEASTERLY WINDS UP ALONG THE SOUTHWEST COAST
TONIGHT. A COASTAL FLOOD ADVISORY FOR THE KUSKOKWIM DELTA COAST
REMAINS IN EFFECT THROUGH 9 PM TOMORROW DUE TO THESE STRONG ALONG-
SHORE WINDS CAUSING AN ONSHORE SURGE OF WATER. WATER LEVELS ARE
EXPECTED TO REACH 1.5 TO 2.5 FEET ABOVE THE NORMAL HIGHEST TIDE
LINE DURING HIGH TIDE TODAY AND TOMORROW, AND RECEDE BETWEEN THE
MAIN HIGH TIDES EACH DAY. LIGHT RAIN SPREADS INLAND WITH THE FRONT
ON SUNDAY MORNING, SLOWLY WEAKENING THROUGH 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. THIS IS SOMETHING WE WILL
CONTINUE TO KEEP A CLOSE EYE ON.
.LONG TERM FORECAST (DAYS 4 THROUGH 7: TUESDAY THROUGH
FRIDAY)...
ABOVE NORMAL PRECIPITATION CHANCES AND BELOW NORMAL TEMPERATURES
REMAIN FORECAST FOR THE ENTIRE STATE AND THROUGH THE FIRST HALF OF
THE LONG TERM PERIOD. A BROAD UPPER LOW/LONGWAVE TROUGH IS
FORECAST TO BE ESTABLISHED OVER THE BERING AND WESTERN ALASKA ON
TUESDAY. UNSETTLED WEATHER CHANCES WILL PERSIST WITH SHOWERY
CONDITIONS LIKELY BENEATH THE UPPER LOW ACROSS SOUTHWEST ALASKA
AND THE BERING, WHILE SHORTWAVES LIFTING AHEAD OF THE TROUGH WILL
POSE ELEVATED RAIN CHANCES FOR SOUTHCENTRAL ALASKA AS WELL.
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. A BREAK FROM PRECIPITATION CHANCES MAY THEN DEVELOP
ON THURSDAY AND FRIDAY BETWEEN SYSTEMS.
- BL
AVIATION
PANC...SOUTHERLY WINDS WILL REMAIN MUCH LIGHTER AT THE TERMINAL
TODAY AS VFR CONDITIONS PERSIST. LINGERING SHOWERS SHOULD ALSO
CLEAR OUT BY MIDDAY TODAY. STRONGER AND GUSTY SOUTHEAST WINDS
COMING UP FROM THE TURNAGAIN ARM WILL START UP AGAIN LATE TONIGHT
INTO SUNDAY MORNING.
- AS
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