954
FXPQ50 PGUM 270824
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
624 PM CHST TUE OCT 27 2026
MARIANAS SYNOPSIS
LIGHT TO GENTLE NORTH WINDS ARE VISIBLE OVER GUAM AND ROTA THIS
EVENING WITH GENTLE TO MODERATE EAST-NORTHEASTERLIES OVER TINIAN AND
SAIPAN. ISOLATED SHOWERS REMAIN OVER GUAM AND ROTA WITH HIGH-END
SCATTERED SHOWERS OVER TINIAN AND SAIPAN AS A TROUGH MOVES THROUGH
SLOWLY. MODEL AND OBSERVATION DATA INDICATE COMBINED SEAS OF 5 TO 6
FEET.
DISCUSSION
ISOLATED SHOWERS TONIGHT ACROSS GUAM AND ROTA ARE EXPECTED TO
CONTINUE FOR THE WHOLE FORECAST PERIOD WITH THE EXCEPTION OF
SCATTERED ISLAND EFFECT SHOWERS IN THE AFTERNOON WEDNESDAY. FOR THE
TINIAN AND SAIPAN, A TROUGH WILL CONTINUE TO MOVE THROUGH THE REGION
AND BRING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS TONIGHT,
BECOMING ISOLATED WEDNESDAY. SHOWERS WILL LIKELY REMAIN ISOLATED
UNTIL FRIDAY WHEN SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS RETURN
UPON THE PASSAGE OF TYPHOON IN-FA SOMEWHERE TO THE NORTH THROUGH THE
FAR NORTHERN CNMI ANYWHERE FROM JUST NORTH OF SAIPAN TO MAUG ISLAND.
SHOWERS FOR TINIAN AND SAIPAN WILL LIKELY RETURN TO ISOLATED FOR THE
REST OF THE FORECAST PERIOD BY SATURDAY. CURRENT TYPHOON IN-FA IS
EXPECTED TO MAKE IT'S CLOSEST POINT OF APPROACH SOMETIME FRIDAY.
BREEZY CONDITIONS CAN BE EXPECTED FOR TINIAN AND SAIPAN FRIDAY WITH
SUSTAINED WINDS UP TO 30 MPH AND GUSTS TO 45 MPH. THE CURRENT JTWC
TRACK PUTS ONLY A 10-20% CHANCE OF TROPICAL STORM SUSTAINED WINDS FOR
TINIAN AND SAIPAN. THIS SITUATION REMAINS HIGHLY UNCERTAIN AND WILL
CONTINUE TO BE MONITORED CLOSELY FOR ANY POTENTIAL CHANGES. SEE THE
"TROPICAL SYSTEMS" SECTION FOR MORE DETAILS.
MARINE
GENTLE NORTHEAST WINDS WILL PREVAIL ACROSS TINIAN AND SAIPAN
THROUGH AT LEAST WEDNESDAY NIGHT, WHILE MOSTLY LIGHT WINDS PREVAIL
OVER ROTA AND GUAM. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WILL BE POSSIBLE FOR TINIAN AND SAIPAN TONIGHT AS A TROUGH MOVES
THROUGH THE REGION, WITH ISOLATED THUNDERSTORMS POSSIBLE FOR ALL
ISLANDS WEDNESDAY. THEREFORE, THERE IS A MODERATE RISK OF LIGHTNING
ALONG THE COASTLINES TONIGHT FOR TINIAN AND SAIPAN, AND ALL ISLANDS
WEDNESDAY. THERE WILL BE A MODERATE RISK OF RIP CURRENTS ALL WEEK FOR NORTH-
AND EAST-FACING REEFS DUE TO A PRIMARY EAST-NORTHEAST SWELL AND A
SECONDARY WEST-NORTHWEST SWELL THAT WILL BECOME NEGLIGIBLE BY
WEDNESDAY. COMBINED SEAS ARE EXPECTED TO WAVER BETWEEN 5 AND 6 FEET
THROUGH THURSDAY. BY LATE THURSDAY, SEAS ARE EXPECTED TO INCREASE
SIGNIFICANTLY AND BECOME HAZARDOUS AHEAD OF TYPHOON IN-FA THAT IS
ANTICIPATED TO PASS SOMEWHERE THROUGH THE FAR NORTHERN CNMI BETWEEN
JUST NORTH OF SAIPAN TO MAUG ISLAND. WIDESPREAD SEAS OF 10 TO 15 FEET
ARE EXPECTED FOR TINIAN AND SAIPAN WITH SEAS POTENTIALLY UP TO 20
FEET POSSIBLE IF IN-FA TAKES A MORE SOUTHERN TRACK. SEAS OF 10+ FEET
ARE ALSO POSSIBLE FOR GUAM AND ROTA. THEREFORE, THE SURF WILL ALSO BE
HAZARDOUS ON ALL ISLANDS, PARTICULARITY FOR NORTH AND EAST FACING
REEFS.
TROPICAL SYSTEMS
AT 1 PM CHST, TYPHOON IN-FA WAS LOCATED 205 MILES NORTH OF ENEWETAK,
ABOUT 1265 MILES EAST OF GUAM, NEAR 14N162E. IN-FA IS NEARLY
STATIONARY, MOVING WEST AT ONLY 1 MPH. MAXIMUM SUSTAINED WINDS WERE
125 MPH. TY IN-FA IS EXPECTED TO MOVE WEST THROUGH THURSDAY, THEN
BEGIN TO TURN WEST-NORTHWEST BY FRIDAY, HEADING TOWARD THE ISLAND OF
PAGAN IN THE FAR NORTHERN CNMI. IN-FA IS EXPECTED TO WEAKEN SLIGHTLY
THROUGH TONIGHT, THEN BEGIN TO STRENGTHEN AGAIN WEDNESDAY. TY IN-FA
COULD BECOME A SUPER TYPHOON AS EARLY AS THURSDAY, AND REACH THE
NORTHERN CNMI AT THAT INTENSITY FRIDAY AFTERNOON. RESIDENTS OF
TINIAN, SAIPAN AND THE FAR NORTHERN CNMI SHOULD CONTINUE TO MONITOR
FORECASTS FOR ANY UPDATES OR CHANGES AND THE POSSIBILITY OF ANY
WATCHES OR WARNINGS, AS CHANGES IN INTENSITY, TRACK AND TIMING WILL
OCCUR OVER THE NEXT FEW DAYS. A SIGNIFICANT SHIFT SOUTH COULD BRING
TC CONDITIONS TO TINIAN AND SAIPAN, THOUGH THIS IS NOT EXPECTED AT
THIS TIME.
FOR MORE INFORMATION ON TY IN-FA, SEE BULLETINS ISSUED BY THE JOINT
TYPHOON WARNING CENTER UNDER WMO HEADER WTPN31 PGTW AND BY THE
NATIONAL WEATHER SERVICE UNDER WMO HEADER WTPQ31 PGUM.
EASTERN MICRONESIA
A FAIRLY DRY PATTERN IS IN STORE FOR EASTERN MICRONESIA THROUGH THE
WEEKEND. MOSTLY CLEAR SKIES ARE EXPECTED AT MAJURO AND KOSRAE
TONIGHT, CONTINUING AT KOSRAE THROUGH WEDNESDAY NIGHT. THE MOST THAT
CAN BE EXPECTED FOR POHNPEI AND KOSRAE IS ONLY ISOLATED SHOWERS
THROUGH THE WEEKEND. FOR MAJURO, THE MONSOON TROUGH LOOKS TO DRIFT
WEST OVER THE NEXT COUPLE DAYS, WITH A BAND OF WEAK CONVERGENCE
SETTING UP BRIEFLY OVER MAJURO. THIS IS EXPECTED TO BRING SCATTERED
SHOWERS TO THE ATOLL WEDNESDAY THROUGH WEDNESDAY NIGHT. BY THURSDAY,
THE DRY PATTERN LOOKS TO RETURN TO MAJURO.
FOR THE MARINE FORECAST, NOTHING HAS REALLY CHANGED. STILL LOOKS LIKE
COMBINED SEAS AT OR BELOW 6 FEET THROUGH THE WEEKEND. GENTLE TO
MODERATE WINDS AT POHNPEI WILL SUBSIDE TO LIGHT TO GENTLE BY
THURSDAY, WHILE LIGHT TO GENTLE WINDS WILL PREVAIL AT KOSRAE AND
MAJURO THROUGH THE WEEKEND.
WESTERN MICRONESIA
THE MAIN FORECAST CHALLENGE CONTINUES TO BE ANY RAINFALL FOR PALAU
AND YAP IN THE SHORT TERM, AS THE MONSOON TROUGH REMAINS OVERHEAD OR
VERY NEAR HERE. HOWEVER, THE LATEST INFRARED SATELLITE IMAGERY SHOWS
RAPIDLY WARMING CLOUD TOPS. A WEAK CIRCULATION THAT WAS NEAR THERE
THE LAST 48 HRS HAS DISSOLVED. AS SUCH, OPTED FOR JUST ISOLATED
SHOWERS THROUGH THURSDAY NIGHT. THEREAFTER, THE SOUTHWEST MONSOON
FLOW WILL BRIEFLY STRENGTHEN AT CHUUK THURSDAY, ASSOCIATED WITH
TYPHOON IN-FA. THEN, IT QUICKLY (THE MONSOON TROUGH AND AREA OF
INCREASED WINDS/SURFACE CONVERGENCE) PEELS WEST THURSDAY NIGHT,
ARRIVING AND PALAU AND YAP FRIDAY INTO SATURDAY. THIS WILL NEED TO BE
WATCHED THOUGH (IN-FA AND THE MONSOON TROUGH) AS THERE'S SOME
CONCERNS THAT IN-FA COULD TAKE A MORE SOUTHERLY TRACK THEN CURRENTLY
FORECAST, WHICH COULD IN TURN PROLONG INFLOW-RELATED CONVECTION.
OTHERWISE, SEAS OF 3 TO 5 FEET WILL BRIEFLY INCREASE A FOOT FRIDAY,
INTO SATURDAY, MAINLY NEAR YAP, AS IN-FA PASSES THROUGH THE NORTHERN
CNMI, THE WINDS WILL GENERALLY BE LIGHT TO GENTLE, ALBEIT BRIEFLY
HIGHER AT CHUUK THURSDAY AS THE SOUTHWESTERLY INFLOW INTO IN-FA
BRIEFLY STRENGTHENS.
GUM WATCHES/WARNINGS/ADVISORIES
GU...NONE.
MP...NONE.
MARIANAS WATERS...NONE.
MARIANAS: OGLE
EAST MICRONESIA/TROPICAL: KLEESCHULTE
WEST MICRONESIA: DOLL
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