743
FXPQ50 PGUM 260823
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
623 PM CHST MON OCT 26 2026
MARIANAS SYNOPSIS
GENTLE TO MODERATE EAST-NORTHEASTERLIES PREVAIL ACROSS THE MARIANAS
THIS EVENING. ISOLATED TO SCATTERED SHOWERS ARE VISIBLE ON RADAR AND
SATELLITE. MODEL AND OBSERVATION DATA INDICATE COMBINED SEAS OF
AROUND 6 FEET.
DISCUSSION
ISOLATED SHOWERS TONIGHT ACROSS THE MARIANAS ARE EXPECTED TO
CONTINUE FOR GUAM FOR THE WHOLE FORECAST PERIOD WITH THE EXCEPTION OF
SCATTERED ISLAND EFFECT SHOWERS IN THE AFTERNOON TUESDAY AND
WEDNESDAY. DUE TO LIGHT NORTHEAST OR NORTH WINDS, THESE WILL LIKELY
BE CONCENTRATED MORE OVER CENTRAL AND SOUTHERN GUAM. FOR THE CNMI, A
TROUGH IS EXPECTED TO MOVE INTO THE REGION AND BRING A PERIOD OF
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS BEFORE RETURNING BACK TO
ISOLATED TUESDAY NIGHT. SHOWERS WILL LIKELY REMAIN ISOLATED UNTIL
FRIDAY WHEN COVERAGE CHANGES TO SCATTERED UPON THE PASSAGE OF TYPHOON
IN-FA SOMEWHERE TO THE NORTH THROUGH THE FAR NORTHERN CNMI. CURRENT
TYPHOON IN-FA IS EXPECTED TO MAKE IT'S CLOSEST POINT OF APPROACH
SOMETIME FRIDAY OR EARLY SATURDAY WHICH WILL BRING SCATTERED SHOWERS
FOR THE CNMI AND POTENTIALLY BREEZY CONDITIONS. THE CURRENT JTWC
TRACK PUTS A 30% CHANCE OF TROPICAL STORM SUSTAINED WINDS FOR TINIAN
AND SAIPAN AND ONLY 10% FOR ROTA. THIS SITUATION REMAINS HIGHLY
UNCERTAIN, THOUGH MOST MODELS SHOW A PASSAGE THROUGH THE REMOTE, FAR
NORTHERN CNMI SOMEWHERE BETWEEN JUST NORTH OF SAIPAN TO AS FAR NORTH
AS MAUG ISLAND. THIS WILL CONTINUE TO BE MONITORED CLOSELY FOR ANY
POTENTIAL CHANGES. SEE THE "TROPICAL SYSTEMS" SECTION FOR MORE
DETAILS.
MARINE
..HAZARDOUS SEAS AND SURF LIKELY FRIDAY THROUGH EARLY SATURDAY
GENTLE EASTERLIES WILL PREVAIL ACROSS TINIAN AND SAIPAN THROUGH AT
LEAST WEDNESDAY NIGHT, BECOMING LIGHT OVER ROTA AND GUAM COASTAL
WATERS TONIGHT. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL BE
POSSIBLE FOR THE CNMI TUESDAY AS A TROUGH MOVES INTO THE REGION.
THEREFORE, THERE IS A MODERATE RISK OF LIGHTNING FOR THE CNMI
TUESDAY. THERE WILL BE A MODERATE RISK OF RIP CURRENTS THROUGH AT
LEAST TUESDAY FOR WEST-, NORTH-, AND EAST-FACING REEFS DUE TO A
PRIMARY EAST-NORTHEAST SWELL AND A SECONDARY WEST-NORTHWEST SWELL.
COMBINED SEAS ARE EXPECTED TO WAVER BETWEEN 5 AND 6 FEET THROUGH
THURSDAY. BY LATE THURSDAY OR FRIDAY, SEAS ARE EXPECTED TO INCREASE
SIGNIFICANTLY AND BECOME HAZARDOUS AHEAD OF CURRENT TYPHOON IN-FA.
WIDESPREAD SEAS OF 10 TO 15 FEET ARE EXPECTED WITH SEAS UP TO 20 FEET
POSSIBLE FOR TINIAN AND SAIPAN IF IN-FA TAKES A SOUTHERN TRACK.
MARINERS SHOULD START TO PLAN NOW AND TAKE ANY NECESSARY PRECAUTIONS.
TROPICAL SYSTEMS
AT 100 PM CHST, THE CENTER OF TYPHOON IN-FA WAS LOCATED NEAR 13.9N
163.1E. IN-FA WAS MOVING WEST-NORTHWEST AT 9 MPH. MAXIMUM SUSTAINED
WINDS WERE 90 MPH. IN-FA IS EXPECTED TO MAINTAIN THIS GENERAL COURSE
WITH A DECREASE IN FORWARD SPEED OVER THE NEXT COUPLE OF DAYS. THE
LATEST FORECAST TRACK TAKES IN-FA TO THE NORTH OF SAIPAN, NEAR PAGAN
LATE IN THE WEEKEND OR OVER THE WEEKEND. IN-FA IS ALSO EXPECTED TO
STRENGTHEN OVER THE NEXT COUPLE OF DAYS, LIKELY BECOMING A CATEGORY 2
TYPHOON LATER THIS EVENING AND CATEGORY 3 AROUND THURSDAY. ALTHOUGH
TY IN-FA IS EXPECTED TO MOVE THROUGH THE FAR NORTHERN CNMI, IT IS
IMPORTANT TO REMEMBER THAT THE EXPECTED TRACK, SPEED AND INTENSITY
MAY, AND LIKELY WILL, CHANGE OVER THE NEXT COUPLE OF DAYS. THEREFORE,
RESIDENTS OF ALL ISLANDS IN THE CNMI NEED TO MONITOR PROGRESS AND
CHANGES TO THE FORECAST.
TYPHOON FORCE WINDS EXTEND OUTWARD FROM THE CENTER UP TO 15 MILES.
TROPICAL STORM FORCE WINDS EXTEND OUTWARD FROM THE CENTER UP TO 75
MILES.
EASTERN MICRONESIA
A PRETTY DRY PATTERN IS IN PLACE ACROSS EASTERN MICRONESIA THIS
AFTERNOON. LITTLE TO NO SHOWERS ARE PRESENT ACROSS KOSRAE AND THE
MARSHALL ISLANDS, SOUTH OF 10N. POHNPEI IS SEEING A FEW MORE SHOWERS,
THOUGH NOTHING MORE THAN ISOLATED. FOR KOSRAE AND MAJURO, THIS DRY
PATTERN LOOKS TO CONTINUE FOR THE NEXT SEVERAL DAYS, WITH MAJURO
SEEING NO SHOWERS TUESDAY OR TUESDAY NIGHT, WITH ONLY ISOLATED
SHOWERS EXPECTED FOR THE REMAINDER OF THE WEEK. KOSRAE CAN EXPECT
ONLY ISOLATED SHOWERS INTO THE WEEKEND. FOR POHNPEI, THE DRY PATTERN
LOOKS TO CHANGE A BIT AROUND TUESDAY NIGHT. AS TY IN-FA MOVES WEST-
NORTHWEST, EXPECT A BAND OF CONVECTION, ASSOCIATED WITH A FEEDER
BAND INTO THE TYPHOON, TO MOVE OVER POHNPEI. THIS WILL PRODUCE A
COUPLE OF DAYS OF INCREASED CONVECTION OVER THE ISLAND, WITH POPS
(PROBABILITY OF PRECIPITATION) IN THE 30 TO 40 PERCENT RANGE. POPS
LOOK TO DECREASE TO 20 PERCENT AGAIN AROUND FRIDAY.
FOR THE MARINE FORECAST, NOTHING REALLY SIGNIFICANT IS EXPECTED.
COMBINED SEAS LOOK TO REMAIN AT OR BELOW 6 FEET. GENTLE TO MODERATE
WINDS WILL CONTINUE AT POHNPEI INTO THURSDAY AS IN-FA CONTINUES TO
MOVE FARTHER AWAY FROM THE ISLAND. ELSEWHERE, LIGHT TO GENTLE WINDS
WILL PREVAIL INTO THE WEEKEND.
WESTERN MICRONESIA
THE MAIN FOCUS IN THE SHORT TERM (NEXT 48 HOURS) WAS RAINFALL
COVERAGE/POTENTIAL, WHEN PERIODS OF SCATTERED SHOWERS LOOK PROBABLE.
PALAU SAW LIGHT SHOWERS (ISLAND CONVECTION) DEVELOP THIS AFTERNOON
UNDER LIGHT WINDS, AND A REPEAT PERFORMANCE IS ANTICIPATED TUESDAY.
MEANWHILE, YAP WILL SEE INCREASING SHOWER POTENTIAL, AS SURFACE
CONVERGENCE INCREASES DUE TO A SURFACE TROUGH TO THE NORTHEAST
MOVING OVERHEAD. THEN AT CHUUK, A MONSOON WEST TO SOUTHWEST FLOW
INTO TYPHOON IN-FA HAS DEVELOPED, AUGMENTED BY A WEAK CIRCULATION
NEAR SATAWAL.
HEADING INTO THE LATTER HALF OF THE WEEK, A NORTH TO NORTHEASTERLY
SWELL WILL ARRIVE INITALLY AT CHUUK, MOVING WEST WITH TIME, AS IN-FA
WILL LIKELY BE A STRONG TYPHOON OR SUPER TYPHOON AS IT CROSSES THE
FAR NORTHERN CNMI. AT THIS TIME, GIVEN IN-FAS FAST PROJECTED FORWARD
SPEED, MAXIMUM WAVE HEIGHTS LOOK TO REMAIN BELOW HIGH SURF AND SMALL
CRAFT CRITERIA. HOWEVER, DEPENDING HOW THINGS UNFOLD, A HEADLINE FOR
ELEVATED SURF MAY BE NEEDED AT YAP OR CHUUK LATER THIS WEEK. WINDS
WILL GENERALLY BE LIGHT TO GENTLE AREA-WIDE FOR THE REST OF THE
WEEK.
GUM WATCHES/WARNINGS/ADVISORIES
GU...NONE.
MP...NONE.
MARIANAS WATERS...NONE.
MARIANAS: OGLE
EAST MICRONESIA/TROPICAL: KLEESCHULTE
WEST MICRONESIA: DOLL
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