702
FXPQ50 PGUM 230639
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
439 PM CHST FRI OCT 23 2026
MARIANAS SYNOPSIS
GENTLE TO MODERATE EASTERLIES PREVAIL ACROSS THE MARIANAS. SATELLITE
IMAGERY AND DOPPLER RADAR INDICATE A FEW SHOWERS IN GUAM WATERS, WITH
MOST OF THE CONVECTION REMAINING NORTH OF SAIPAN WATERS. RECENT
ALTIMETRY PASSES SHOW 6 TO 8 FOOT SEAS TO THE WEST.
DISCUSSION
THE BROAD TROUGH EXTENDING FROM TROPICAL DISTURBANCE 98W IN EASTERN
YAP STATE HAS FINALLY MADE IT TO THE REGION, TO THEN EXIT TO THE WEST
AS ANOTHER CONVERGENCE ZONE FORMS IN ITS PLACE, BRINGING PATCHY
SHOWERS AND SOME THUNDERSTORMS SATURDAY AND SATURDAY NIGHT.
DIFFUSIVE FLOW WILL ENSUE THEREAFTER, ALLOWING MOSTLY PLEASANT
WEATHER TO RETURN TO THE MARIANAS BEGINNING EARLY NEXT WEEK.
MARINE
COMBINED SEAS OF 6 TO 8 FEET WILL PERSIST THROUGH SATURDAY AND THEN
BEGIN TO SLOWLY TAPER DOWN THEREAFTER, AS NORTHEASTERLY SWELL AND
WESTERLY SWELLS CONTINUE TO DIMINISH. A MODERATE RISK OF RIP
CURRENTS IS EXPECTED ALONG NORTH, EAST, AND WEST FACING REEFS OF THE
MARIANAS THROUGH SATURDAY NIGHT. THEN, RIP CURRENT RISK MAY DROP TO
LOW ALONG WEST FACING REEFS AS THE AFOREMENTIONED SWELLS DECREASE.
TROPICAL SYSTEMS
A DEVELOPING TROPICAL DISTURBANCE, THE JOINT TYPHOON WARNING CENTER
(JTWC)'S INVEST 97W, IS CENTERED OVER THE NORTHERN MARSHALL ISLANDS
NEAR 11N166E, AND HAS MOVED VERY LITTLE OVER THE LAST 24 HOURS. AS OF
1130 AM CHST (0130 UTC), INVEST 97W IS NOW THE SUBJECT OF A TROPICAL
CYCLONE FORMATION ALERT (TCFA), RATED "HIGH" FOR DEVELOPMENT,
MEANING DEVELOPMENT INTO A SIGNIFICANT TROPICAL CYCLONE (A TROPICAL
DEPRESSION) IS EXPECTED WITHIN 24 HOURS. HIMAWARI VISIBLE SATELLITE
IMAGERY THIS AFTERNOON SHOWS WIDESPREAD SHOWERS AND ISOLATED
THUNDERSTORMS ACROSS THE MARSHALLS NORTH OF MAJURO, EXTENDING
EASTWARD TO BEYOND THE DATE LINE, WITHIN A BROAD, ELONGATED REGION OF
CYCLONIC TURNING. DEEP CONVECTION IS BUILDING OVER AND JUST WEST OF
THE CENTER IN THE VICINITY OF ENEWETAK, BIKINI, AND RONGELAP ATOLLS.
MODELS FAVOR 97W DEVELOPING RAPIDLY IN THE NEXT FEW DAYS, REMAINING
QUASI-STATIONARY THROUGH SATURDAY BEFORE GRADUALLY LIFTING NORTH OUT
OF THE RMI AROUND SATURDAY NIGHT, LIKELY AS A TROPICAL DEPRESSION OR
EVEN A LOW-END TROPICAL STORM. THE TRACK OF 97W THEN BECOMES MORE
UNCERTAIN, WITH MOST SOLUTIONS SHOWING A VERY SLOW NORTHEAST
MEANDERING THROUGH EARLY NEXT WEEK, BEFORE AN EVENTUAL WESTWARD TURN
BY THE END OF NEXT WEEK.
IN THE MEANTIME, INVEST 97W WILL MAINTAIN A WET AND GUSTY PATTERN
ACROSS THE NORTHERN MARSHALLS FOR THE NEXT DAY OR TWO.
SCATTEROMETRY FROM THIS MORNING SHOWED FRESH TO STRONG WESTERLY
WINDS JUST SOUTH OF 97W'S CENTER, OVER THE WESTERNMOST ISLANDS AND
ATOLLS OF THE CENTRAL RMI. SURFACE OBSERVATIONS ON KWAJALEIN ISLAND
SHOW MODERATE TO FRESH WESTERLY WINDS WITH FREQUENT STRONG GUSTS
OVER 25 MPH, AND SIGNIFICANT BOAT DAMAGE WAS REPORTED THIS MORNING
THERE ALONG WESTERN EXPOSURES. WESTERLY WINDS OVER THE CENTRAL
WESTERN MARSHALLS WILL STRENGTHEN AND SHIFT SOUTHWESTERLY THROUGH THE
WEEKEND AS 97W DEVELOPS AND MOVES NORTHWARD. THIS WILL BE CLOSELY
MONITORED FOR ADDITIONAL IMPACTS ACROSS THE MARSHALL ISLANDS, AND A
SPECIAL WEATHER STATEMENT WAS ISSUED FOR MAJURO AND THE
CENTRAL/NORTHERN RMI.
ANOTHER WEAK TROPICAL DISTURBANCE IS SEEN OVER FAR EASTERN YAP
STATE NEAR 9N147E, JTWC'S INVEST 98W. 98W IS A VERY BROAD, WEAK
CIRCULATION SPANNING NEARLY THE ENTIRETY OF YAP AND CHUUK STATES.
MOST OF THE CONVECTION IS SEEN WITHIN THE SOUTH TO SOUTH-SOUTHWEST
FLOW ALONG ITS EASTERN PERIPHERY, COVERING CHUUK LAGOON AND SATAWAL,
AND TO THE WEST NEAR YAP. ALONG THE NORTHERN EDGE OF INVEST 98W,
SCATTERED SHOWERS ARE SEEN WITHIN A WESTWARD-PROPAGATING TRADE-WIND
TROUGH, MOVING ACROSS THE NORTHERN CNMI THIS AFTERNOON. INVEST 98W
IS STILL RATED "SUB-LOW," MEANING IT IS NOT FAVORED TO DEVELOP MUCH
IN THE NEXT FEW DAYS AS IT CONTINUES WESTWARD ACROSS YAP STATE.
HOWEVER, IT STILL LOOKS TO MAINTAIN GENERALLY WETTER CONDITIONS FOR
CHUUK TONIGHT, AND THE MARIANAS THROUGH THE WEEKEND.
FOR MORE INFORMATION ON INVEST 97W, SEE BULLETINS ISSUED BY JTWC
UNDER WMO HEADER ABPW10 PGTW. ADDITIONAL INFORMATION ON INVEST
98W MAY BE FOUND THERE AS WELL, IF IT BECOMES RATED "LOW" FOR
DEVELOPMENT OR HIGHER.
EASTERN MICRONESIA
POHNPEI AND KOSRAE REMAIN WITHIN A FAIRLY DRY RIDGING PATTERN THIS
AFTERNOON, WHILE MAJURO SITS JUST SOUTHEAST OF DEVELOPING INVEST 97W,
DISCUSSED IN THE TROPICAL SYSTEMS SECTION ABOVE. NUMEROUS TO
WIDESPREAD SHOWERS ARE SEEN ACROSS THE MARSHALL ISLANDS NORTH OF
MAJURO ATOLL, BUT ARE SCATTERED NEAR MAJURO ITSELF. INVEST 97W,
CURRENTLY CENTERED NEAR 11N166E, WILL BE THE PRIMARY WEATHER CONCERN
WITHIN EASTERN MICRONESIA FOR THE NEXT FEW DAYS, PRODUCING A SURGE IN
WEST WINDS AND SWELL ACROSS THE CENTRAL AND NORTHERN RMI AS IT
STRENGTHENS NEAR RONGELAP ATOLL. A SPECIAL WEATHER STATEMENT WAS
ISSUED EARLIER THIS AFTERNOON FOR IMPACTS RELATED TO INVEST 97W.
MODERATE WEST TO SOUTHWEST WINDS WITH STRONG GUSTS TO 25 KTS ARE
EXPECTED FOR MAJURO THROUGH SUNDAY AS 97W GRADUALLY LIFTS NORTH OUT
OF THE MARSHALL ISLANDS, BUT MOST OF THE SHOWERS ARE EXPECTED TO STAY
NORTH OF MAJURO. LOCALLY HEAVY SHOWERS WILL BE POSSIBLE TONIGHT, AND
OUTFLOW BOUNDARIES COULD PRODUCE STRONG GUSTS AT TIMES, WITH HIGHER
WINDS, GUSTS, AND IMPACTS EXPECTED FOR ISLANDS AND ATOLLS ALONG THE
CENTRAL RALIK CHAIN, SUCH AS UJAE AND KWAJALEIN ATOLL, WHERE BOAT
DAMAGE WAS REPORTED THIS MORNING ALONG WESTERN EXPOSURES. WEST WINDS
WILL SHIFT SOUTHWESTERLY THIS WEEKEND AS 97W ORGANIZES AND SHIFTS
NORTH. BOATS SHOULD BE SAFELY SECURED AWAY FROM WEST AND SOUTH-FACING
EXPOSURES OVER THE NEXT FEW DAYS, IF POSSIBLE. WINDS WILL DIMINISH
EARLY NEXT WEEK, BUT ELEVATED WEST TO SOUTHWEST SWELL WILL
CONTINUE FOR THE RMI FOR SLIGHTLY LONGER, AND SURF ALONG THESE
EXPOSURES WILL REMAIN ELEVATED AS WELL.
FOR KOSRAE AND POHNPEI, WEST TO SOUTHWEST WINDS ARE EXPECTED TO
REMAIN LIGHT TO MODERATE THROUGH THE FORECAST PERIOD. CONVERGENT
WEST TO SOUTHWEST FLOW WILL BRING SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS AT TIMES SATURDAY NIGHT THROUGH MONDAY. GENERALLY
BENIGN MARINE CONDITIONS WILL PREVAIL, WITH COMBINED SEAS OF 4 TO 7
FEET EXPECTED ACROSS THE REGION, COMPRISED OF A PRIMARY NORTH SWELL
AND A SECONDARY SOUTHEAST SWELL, BUT WEST TO SOUTHWEST SWELL IS
EXPECTED TO BUILD IN FOR MAJURO THIS WEEKEND AS COMBINED SEAS
INCREASE BY A FOOT OR SO, PRODUCING ELEVATED, POTENTIALLY HAZARDOUS
SURF ALONG WEST- AND SOUTH- FACING REEFS AROUND SUNDAY. SEAS WILL BE
CHOPPY ACROSS THE NORTHERN MARSHALLS THIS WEEKEND AS INVEST 97W
DEVELOPS, AND INTER-ISLAND TRAVEL IS DISCOURAGED. COMBINED SEAS
COULD EXCEED 10 FEET ACROSS PARTS OF THE NORTHERN RMI BY SATURDAY
EVENING, BRINGING CONDITIONS HAZARDOUS TO SMALL CRAFT.
WESTERN MICRONESIA
THE "GAMES AFOOT" TODAY, AS AN UNEXPECTED LOW HAS FORMED BETWEEN
EAURIPIK AND SOROL. CONVERGENCE ON THE BACKSIDE OF THIS CIRCULATION
IS BRINGING SCATTERED SHOWERS AND THUNDERSTORMS TO YAP. MEANWHILE, TO
ITS EAST WE HAVE INVEST 98W (RATED AS "SUB-LOW" BY THE JOINT TYPHOON
WARNING CENTER), WHICH CONTINUES TO MEANDER/DRIFT SLOWLY NORTH-
NORTHWEST. IT APPEARS 97W AND THE SOROL LOW ARE IN A MERGING PROCESS,
WITH TODAY'S MODEL RUNS SHOWING THIS FEATURE WASHING OUT IN 48 TO 72
HOURS. UNTIL THEN, THESE DISTURBANCES WILL BRING PERIODS OF
SCATTERED SHOWERS TO YAP AND CHUUK, WITH A FEW THUNDERSTORMS POSSIBLE
AS WELL, MAINLY AT YAP.
IT REMAINS IF NORTHERN PALAU WILL "GET IN ON THIS ACTION (RAINFALL)",
BEFORE THE SYSTEM DISSOLVES. WE OPTED FOR A "MIDDLE GROUND APPROACH"
IN THE FORECAST, RAISING RAINFALL PROBABILITIES SIGNIFICANTLY AT YAP
FOR THE NEXT 48 HOURS, AND SLIGHTLY BUT SUFFICIENTLY FOR SCATTERED
SHOWERS AT PALAU OVER THE SAME TIME PERIOD. FOR CHUUK, AS THE
DISTURBANCES MERGE/PULL AWAY FROM YOUR AREA, SHOWERS BECOME ISOLATED
IN COVERAGE AFTER TONIGHT.
FOUR OUR MARINERS, LIGHT TO GENTLE WINDS PREVAIL AREA-WIDE, WITH SEAS
IN THE 4 TO 6 FOOT RANGE POSSIBLY DROPPING A FOOT BY THE MIDDLE OF
NEXT WEEK.
SIDE NOTE:
SMOKE FROM INDONESIAN WILDFIRES HAS IMPROVED SLIGHTLY TODAY AT PALAU,
BUT IT MAY STILL AFFECT FOLKS WITH RESPIRATORY ILLNESSES. ALSO, KING
TIDES WILL ELEVATE SURF AND SEA LEVELS SOMEWHAT IN THE COMING DAYS,
BUT NOT TO THE EXTENT ANY EROSION CONCERNS ARE PRESENT.
GUM WATCHES/WARNINGS/ADVISORIES
GU...NONE.
MP...NONE.
MARIANAS WATERS...NONE.
MARIANAS: MONTVILA
EAST MICRONESIA/TROPICAL: DECOU
WEST MICRONESIA: DOLL
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