911
FXPQ50 PGUM 142028
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
628 AM CHST WED APR 15 2026
MARIANAS UPDATE
TYPHOON SINLAKU IS MOVING SLOWLY AND AT TIMES IT HAS BECOME NEARLY
STATIONARY. THIS IS CONTINUING DEVASTATING WINDS OF 115 MPH OR
GREATER OVER TINIAN AND SAIPAN. WHILE HEAVY RAIN BANDS CONTINUE
ACROSS GUAM AND ROTA, BRINGING STRONG GUSTS TO AROUND 70 MPH (SEE
TROPICAL SYSTEMS SECTION BELOW). DUE TO THE SLOW MOTION AND LARGE
SIZE OF SINLAKU, THE FLOOD WATCH WAS EXTENDED THROUGH TONIGHT. FOR
GUAM AND ROTA, WESTERLY WINDS ARE DRIVING THE HIGHEST SURF AND
INUNDATION ALONG WEST FACING REEFS AND WRAPPING AROUND TO NORTH AND
SOUTH FACING REEFS, WHILE RELAXING SOMEWHAT ALONG EAST FACING REEFS.
FOR TINIAN AND SAIPAN, WINDS HAVE SHIFTED TO THE SOUTHEAST AND SOUTH
AS THE CENTER IS NOW WEST-NORTHWEST OF THE ISLANDS. THIS IS PLACING
THE HIGHEST SURF ALONG EAST, SOUTH AND WEST FACING REEFS, BUT AT
SINLAKU MOVE AWAY TO THE NORTHWEST, THE NORTHWEST SWELL WILL
INCREASING, REBUILDING SURF ALONG NORTH FACING REEFS ACROSS THE
ISLANDS. COASTAL FLOOD WARNING CONTINUES THROUGH THURSDAY MORNING,
WITH HIGH SURF WARNING THROUGH THURSDAY AFTERNOON.
TROPICAL SYSTEMS UPDATE...
AS OF 5AM CHST POSITION AND 1 AM CHST FORECAST FROM JTWC, TYPHOON
SINLAKU HAD MAX WINDS OF 145 MPH AND WAS ABOUT 20 MILES NORTHWEST OF
TINIAN, 25 MILES WEST-NORTHWEST OF SAIPAN, 70 MILES NORTH OF ROTA,
AND 125 MILES NORTH-NORTHEAST OF GUAM. THE FORWARD MOTION WAS
NORTHWEST AT 5 MPH OVERNIGHT, BUT RECENT SATELLITE IMAGERY SUGGEST
FORWARD SPEED HAS DECREASED AGAIN AND SINLAKU WAS NEARLY STATIONARY
EARLY THIS MORNING. THIS IS KEEPING SAIPAN AND TINIAN NEAR THE
EASTERN EYEWALL WHERE DEVASTATING WINDS OF 115 MPH OR GREATER ARE
OCCURRING, AND POTENTIALLY PEAKING AT 145 MPH. ROTA AND GUAM ARE
STILL WELL WITHIN THE TROPICAL STORM FORCE WINDS, WITH OBSERVATIONS
ON GUAM REPORTING WINDS AROUND 46 MPH WITH GUSTS OF 71 MPH,
ESPECIALLY AS HEAVY RAIN BANDS CONTINUE TO MOVE OVER THE ISLANDS. IT
WILL TAKE A LONG TIME FOR DECREASE IN THE WINDS ACROSS GUAM, ROTA,
TINIAN AND SAIPAN DUE SINLAKU'S SLOW MOTION AND LARGE SIZE AS
TROPICAL STORM WINDS EXTEND UP TO 265 MILES FROM THE CENTER. WINDS
WILL BE INCREASING AT ALAMAGAN, PAGAN, AND AGRIHAN AS SINLAKU MOVES
NORTHWEST, THEN NORTHERLY AND PASSES TO THE WEST OF THE NORTHERN
ISLANDS, BRINGING STRONG TROPICAL STORM AND POTENTIALLY LOW-END
CATEGORY 1 TO 2 TYPHOON WINDS TOWARD THE END OF THE WEEK.
FOR MORE INFORMATION, PLEASE REFER TO BULLETINS FROM THE JOINT
TYPHOON WARNING CENTER (JTWC) UNDER WMO HEADER WTPN31 PGTW AND FROM
THE NATIONAL WEATHER SERVICE UNDER WMO HEADER WTPQ31 PGUM AND WTPQ81
PGUM.
EASTERN MICRONESIA UPDATE
SATELLITE IMAGERY THIS MORNING SHOWS A BROADLY UNSETTLED PATTERN
ACROSS MUCH OF THE MARSHALL ISLANDS WITH NUMEROUS SHOWERS AND
ISOLATED THUNDERSTORMS, WHILE RELATIVELY QUIET CONDITIONS NEAR
POHNPEI AND KOSRAE. THE CONVECTION BY THE MARSHALL ISLANDS LOOKS TO
BE ALONG CONVERGENT FLOW THAT IS ALONG THE TRADE WINDS AROUND THE
MARSHALL ISLANDS AND THE SOUTHWEST FLOW SOUTH OF TYPHOON SINLAKU
THAT STILL JUST PUSHING INTO POHNPEI. SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS ARE SEEN SOUTH OF POHNPEI AND KOSRAE, NEAR THE EQUATOR,
WITHIN THE SURFACE TROUGH EXTENDING SOUTHWEST FROM STY SINLAKU,
PASSING NEAR CHUUK AND SOUTH OF POHNPEI AND KOSRAE. THE BROAD AREA OF
CONVERGENCE WILL GRADUALLY SHIFT NORTHWARD WITH THE MOVEMENT OF
SINLAKU AND FRAGMENTING THROUGH REST OF THE WEEK, MAINTAINING
SCATTERED TO NUMEROUS SHOWERS FOR THE RMI, INCLUDING MAJURO, OVER THE
NEXT FEW DAYS, WHILE RELATIVELY DRIER CONDITIONS PERSIST FOR KOSRAE
AND POHNPEI. LATEST ALTIMETRY DATA SHOWS 6 TO 8 FOOT SEAS ACROSS MUCH
OF THE REGION. ELEVATED WEST TO NORTHWEST SWELL WILL MAINTAIN
ELEVATED, POTENTIALLY NEAR HAZARDOUS SURF ALONG WEST AND NORTH FACING
REEFS OF POHNPEI THROUGH AT LEAST THE NEXT DAY OR TWO.
WESTERN MICRONESIA UPDATE
SATELLITE IMAGERY SHOWS PARTLY TO MOSTLY CLOUDY SKIES ACROSS PALAU,
YAP, AND CHUUK WITH SHOWERS STILL PATCHY AS DRIER AIR IS BEING PULLED
INT THE REGION SOUTH OF TYPHOON SINLAKU AS IT CONTINUES TO MOVE
NORTHWEST JUST WEST OF TINIAN AND SAIPAN.
FOR CHUUK, NORTHWEST TO SOUTHWEST SWELL ARE KEEPING SURF AND SEAS
ELEVATED BUT SO FAR MODEL GUIDANCE AND ALTIMETRY DATA SUGGEST SEAS
AND SURF BELOW HAZARDOUS THRESHOLDS, AND GUIDANCE SUPPORTS A SLOW
DECREASE IN SEAS AND SURF AS SINLAKU CONTINUES AWAY AND GRADUALLY
WEAKENS OVER THE NEXT FEW DAYS.
FOR YAP AND PALAU, MARINE AND SURF CONDITIONS WILL BE THE MAIN
CONCERN THIS WEEK. LARGE NORTHEAST SWELL FROM DISTANT TYPHOON
SINLAKU CONTINUES TO PRODUCE HAZARDOUS SEAS WITHIN YAP COASTAL WATERS
AND COULD PEAK AROUND 11 TO 13 FEET BEFORE SLOWLY TAPERING OFF ON
THURSDAY. A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR YAP THROUGH
THURSDAY AFTERNOON. THIS LONG-PERIOD SWELL IS ALSO EXPECTED TO BRING
HAZARDOUS SURF ALONG NORTH AND EAST FACING REEFS FACING REEFS OF
YAP, REACHING TO AROUND 9 TO 13 FT. HAZARDOUS SURF, COMBINED WITH
THE HIGHER HIGH TIDES WITH THE NEW MOON CYCLE, THERE MAY BE A CONCERN
FOR SOME MINOR COASTAL INUNDATION ALONG NORTHERN AND EASTERN
SHORELINES AT TIMES OF HIGH TIDE OVER THE NEXT FEW DAYS. HAZARDOUS
SURF HAS ALSO DEVELOPED AT PALAU ALONG NORTH AND EAST FACING REEFS
WITH SURF AROUND 9 TO 13 FEET. SIMILAR TO YAP, MINOR COASTAL
INUNDATION ALONG NORTHERN AND EASTERN REEFS COULD ALSO BE AN ISSUE
DURING HIGH TIDE.
PREV DISCUSSION
/ISSUED 752 PM CHST TUE APR 14 2026/
MARIANAS SYNOPSIS...
SUPER TYPHOON SINLAKU IS SEEN JUST SOUTH-SOUTHEAST OF TINIAN AND
SAIPAN THIS EVENING. TROPICAL STORM FORCE WINDS CONTINUE ACROSS ROTA
AND GUAM, WITH TYPHOON FORCE WINDS OCCURRING AT TINIAN AND SAIPAN.
SINLAKU CONTINUES TO SLOWLY MOVE TOWARD TINIAN AND SAIPAN. NUMEROUS
TO WIDESPREAD LOCALLY HEAVY SHOWERS ARE SEEN ACROSS THE MARIANAS,
WITH ISOLATED THUNDERSTORMS NEAR THE EYE WALL.
DISCUSSION...
NOT MUCH HAS CHANGED FROM THE PREVIOUS FORECAST. SUPER TYPHOON
SINLAKU CONTINUES TO TRACK TOWARD TINIAN AND SAIPAN. TROPICAL STORM
FORCE WINDS REMAIN FROM SOUTH OF GUAM TO THE NORTHERN CNMI, WITH
TYPHOON FORCE WINDS OVER TINIAN AND SAIPAN. WINDS WILL CONTINUE TO
INCREASE AT BOTH TINIAN AND SAIPAN, REACHING AS HIGH AS 150 MPH WITH
GUSTS OVER 180 MPH. THEREFORE, AN EXTREME WIND WARNING WAS ISSUED
FOR BOTH ISLANDS. THIS WARNING WILL BE UPDATED THROUGH THE NIGHT
UNTIL WINDS LOOK TO FALL BELOW 115 MPH SUSTAINED. AFTER EYE PASSAGE
AT TINIAN AND SAIPAN, WINDS WILL GRADUALLY SUBSIDE, BUT LOOK TO
REMAIN AT OR ABOVE TROPICAL STORM FORCE THROUGH THURSDAY AFTERNOON.
FOR GUAM AND ROTA, WINDS ARE PEAKING OR HAVE JUST PEAKED AND WILL BE
SLOWLY SUBSIDING AT BOTH LOCATIONS LATER TONIGHT, THOUGH TROPICAL
STORM FORCE WINDS LOOK TO CONTINUE AT GUAM WEDNESDAY EVENING AND AT
ROTA UNTIL AFTER MIDNIGHT WEDNESDAY. AFTER STY SINLAKU MOVES OUT OF
THE MARIANAS, A DRY PATTERN WILL MOVE INTO THE REGION AND PERSIST FOR
SEVERAL DAYS AFTER.
MARINE...
MARINE CONDITIONS REMAIN DANGEROUS ACROSS THE MARIANAS. SEAS HAVE
PEAKED OVER GUAM AND ROTA WATERS AND ARE EXPECTED TO SLOWLY SUBSIDE
OVER THE NEXT FEW DAYS. SEAS PEAKED IN GUAM AT 26 FEET, AS SHOWN BY
IPAN BUOY IN THE EARLY MORNING HOURS, WHILE REMAINING AROUND 25 TO 30
FEET IN ROTA WATERS. FOR TINIAN AND SAIPAN, SEAS CONTINUE TO
INCREASE, WITH TANAPAG BUOY SHOWING SEAS OF AROUND 26 FEET, WHILE
ALTIMETRY SHOWS OVER 35 FEET TO THE EAST OF THE EYE OF SINLAKU. SEAS
LOOK TO PEAK FOR TINIAN AND SAIPAN AT AROUND 40 FEET TONIGHT,
BEGINNING TO SUBSIDE AFTER SINLAKU MOVES FARTHER NORTH, AWAY FROM THE
ISLANDS. SMALL CRAFT ADVISORY LEVEL SEAS TO HAZARDOUS SEAS LOOK TO
CONTINUE INTO THE WEEKEND, POSSIBLY FALLING BELOW 10 FEET FOR GUAM
AND ROTA EARLY IN THE WEEKEND AND FOR TINIAN AND SAIPAN LATE IN THE
WEEKEND.
HYDROLOGY...
THE ENSEMBLE TROPICAL RAINFALL POTENTIAL (ETRAP) ESTIMATES FROM
MICROWAVE SATELLITE DATA SHOWS THAT 12 TO 20 ADDITIONAL INCHES OF
RAINFALL ARE POSSIBLE NEAR THE CENTER. WITH THE PAST FEW FORECASTS
SUPPORTING PASSAGE NEAR OR OVER TINIAN AND SAIPAN, THESE ISLANDS WILL
HAVE THE GREATEST POTENTIAL FOR THAT RAINFALL. GUAM COULD STILL SEE
A STORM TOTAL OF 6 TO 12 INCHES, WITH ROTA POTENTIALLY REACHING 10 TO
20 INCHES. FLASH FLOODING IS POSSIBLE SO A FLOOD WARNING WAS ISSUED
FOR ALL 4 ISLANDS.
TROPICAL SYSTEMS...
AS OF THE 700 PM CHST PGUA RADAR FIX, SUPER TYPHOON SINLAKU WAS
CENTERED NEAR 14.7N 145.9E, OR ABOUT 25 MILES SOUTHEAST OF TINIAN
AIRPORT, 30 MILES SOUTH-SOUTHEAST OF SAIPAN AIRPORT, AND 115 MILES
NORTHEAST OF GUAM. THE LATEST 6-HOURLY TRACK SHOWS A STEADY WEST-
NORTHWEST MOTION OF AROUND 5 MPH AT 300 DEGREES, WITH THE EYE LOOKING
TO MOVE DIRECTLY OVER OR JUST SOUTH OF TINIAN. HOWEVER, SINLAKU
LOOKS TO BE STALLING JUST SOUTHEAST OF TINIAN, REMAINING NEARLY
STATIONARY OVER THE LAST HOUR OR TWO. RADAR REFLECTIVITY DEPICTS THE
APPEARANCE OF CONCENTRIC EYEWALLS, WITH THE PRIMARY EYEWALL AROUND 10
TO 15 MILES ACROSS AND THE SECONDARY EYEWALL AROUND 50 MILES ACROSS.
BANDS OF HIGH REFLECTIVITY AND HEAVY SHOWERS WITHIN THE OUTERMOST
EYEWALL ARE ROTATING OVER SAIPAN AND TINIAN THIS EVENING AS THE
CENTER OF SINLAKU STALLS TO THE SOUTHEAST, MOVING WEST TO SOUTHWEST
ACROSS THE ISLANDS. SAIPAN HAS BEGUN TO SEE SUSTAINED TYPHOON FORCE
WINDS OF 78 MPH GUSTING TO 113 MPH, WHILE GUAM IS EXPERIENCING
SUSTAINED WINDS AROUND 50 MPH GUSTING TO 76 MPH THIS EVENING. AS
SINLAKU NEARS TINIAN AND SAIPAN, WINDS WILL CONTINUE TO INCREASE,
WITH VERY DANGEROUS, RAPIDLY WORSENING CONDITIONS TONIGHT AS THE
EYEWALL BEGINS TO MOVE OVERHEAD, AND SUSTAINED CATEGORY 4 TYPHOON
FORCE WINDS DEVELOP, WITH 130 TO 150 MPH WINDS GUSTING TO 175 MPH.
OUTSIDE OF THE EYEWALL, THE HIGHEST REFLECTIVITIES AND HEAVIEST
SHOWERS ARE PRESENTLY SEEN IN THE OUTER RAIN BANDS BETWEEN GUAM AND
ROTA, WEST AND SOUTH OF GUAM, AND JUST NORTH TO NORTHEAST OF ROTA
WITHIN THE SECONDARY EYEWALL. THE LATEST FORECAST TRACK FROM THE
JOINT TYPHOON WARNING CENTER (JTWC) MAINTAINS A NORTH-NORTHWEST
PASSAGE OF SINLAKU OVER OR NEAR TINIAN AND SAIPAN LATE TONIGHT WITH
AN INCREASE IN FORWARD SPEED, BUT POTENTIALLY PASSING DIRECTLY OVER
OR SOUTH OF TINIAN IF THE CURRENT TRACK OBSERVED ON RADAR HOLDS.
SINLAKU'S TRACK LOOKS TO SHIFT MORE NORTHWARD AFTER IT CROSSES
TINIAN AND SAIPAN, MOVING THROUGH THE NORTHERN CNMI JUST WEST OF
ALAMAGAN, PAGAN, AND AGRIHAN ON WEDNESDAY THROUGH THURSDAY NIGHT,
BEFORE MAKING A NORTHEAST TURN AWAY BY THE END OF THE WEEK. SUPER
TYPHOON SINLAKU IS ON A GRADUAL WEAKENING TREND THROUGH THE NEXT FEW
DAYS, BUT IS EXPECTED TO MAINTAIN CATEGORY 4 STRENGTH AS IT CROSSES
THE MARIANAS TONIGHT.
EASTERN MICRONESIA...
SATELLITE IMAGERY LATE THIS AFTERNOON SHOWS A BROADLY UNSETTLED
PATTERN ACROSS MUCH OF THE MARSHALL ISLANDS AND RELATIVELY QUIET
CONDITIONS NEAR POHNPEI AND KOSRAE. SCATTERED TO NUMEROUS SHOWERS AND
ISOLATED THUNDERSTORMS ARE SEEN OVER MUCH OF THE RMI INCLUDING
MAJURO AND KWAJALEIN ATOLLS, EXTENDING FURTHER NORTHWEST, PASSING
WEST OF WAKE ISLAND, WITHIN THE BROAD, TRAILING CONVERGENCE INTO
SUPER TYPHOON SINLAKU, FAR WEST-NORTHWEST OF THE REGION. SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS ARE SEEN SOUTH OF POHNPEI AND
KOSRAE, WITHIN THE SURFACE TROUGH EXTENDING SOUTHWEST FROM STY
SINLAKU, PASSING NEAR CHUUK AND SOUTH OF POHNPEI AND KOSRAE. THE
BROAD AREA OF CONVERGENCE WILL GRADUALLY SHIFT NORTHWARD WITH THE
MOVEMENT OF SINLAKU AND FRAGMENT THROUGH REST OF THE WEEK,
MAINTAINING SCATTERED TO NUMEROUS SHOWERS FOR THE RMI, INCLUDING
MAJURO, OVER THE NEXT FEW DAYS, WHILE RELATIVELY DRIER CONDITIONS
PERSIST FOR KOSRAE AND POHNPEI. LATEST ALTIMETRY DATA SHOWS 6 TO 8
FOOT SEAS ACROSS MUCH OF THE REGION. ELEVATED WEST TO NORTHWEST
SWELL WILL MAINTAIN ELEVATED, POTENTIALLY HAZARDOUS SURF ALONG WEST-
FACING REEFS OF POHNPEI THROUGH AT LEAST THE NEXT DAY OR TWO.
WESTERN MICRONESIA...
SATELLITE IMAGERY SHOWS PARTLY TO MOSTLY CLOUDY SKIES AND PATCHY
SHOWERS ACROSS THE REGION AS SUPER TYPHOON (STY) SINLAKU CONTINUES
TO MOVE ACROSS THE MARIANAS, FURTHER DISTANCING ITSELF FROM THE
REGION. THE SMALL CRAFT ADVISORY, HIGH SURF ADVISORY, AND THE COASTAL
FLOOD STATEMENT WAS ALLOWED TO EXPIRE FOR CHUUK AS CONDITIONS ARE
EXPECTED TO GRADUALLY IMPROVE AS SINLAKU MOVES FURTHER AWAY.
FOR YAP AND PALAU, MARINE AND SURF CONDITIONS WILL BE THE MAIN
CONCERN THIS WEEK. LARGE NORTHEAST SWELL FROM DISTANT SUPER TYPHOON
SINLAKU CONTINUES TO PRODUCE HAZARDOUS SEAS WITHIN YAP COASTAL WATERS
AND COULD PEAK AROUND 11 TO 13 FEET BEFORE SLOWLY TAPERING OFF ON
THURSDAY. A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR YAP THROUGH
THURSDAY AFTERNOON. THIS LONG-PERIOD SWELL IS ALSO EXPECTED TO BRING
HAZARDOUS SURF ALONG NORTH FACING REEFS OF YAP, POSSIBLY REACHING
HAZARDOUS LEVELS OF 12 FEET FOR EAST-FACING REEFS. HAZARDOUS SURF,
COMBINED WITH THE HIGHER HIGH TIDES WITH THE NEW MOON CYCLE, THERE
MAY BE A CONCERN FOR SOME MINOR COASTAL INUNDATION ALONG NORTHERN AND
EASTERN SHORELINES AT TIMES OF HIGH TIDE OVER THE NEXT FEW DAYS.
HAZARDOUS SURF IS ALSO EXPECTED AT PALAU, LIKELY REACHING HAZARDOUS
LEVELS OF AT LEAST 9 FEET ALONG NORTH FACING REEFS AND 12 FEET ALONG
EAST FACING REEFS OVERNIGHT.
GUM WATCHES/WARNINGS/ADVISORIES
GU...COASTAL FLOOD WARNING UNTIL 5 AM CHST THURSDAY FOR GUZ001.
FLOOD WATCH THROUGH LATE TONIGHT FOR GUZ001.
HIGH SURF WARNING UNTIL 6 PM CHST THURSDAY FOR GUZ001.
TROPICAL STORM WARNING FOR GUZ001.
TYPHOON WATCH FOR GUZ001.
MP...COASTAL FLOOD WARNING UNTIL 5 AM CHST THURSDAY FOR MPZ001>003.
FLOOD WATCH THROUGH LATE TONIGHT FOR MPZ001>003.
HIGH SURF WARNING UNTIL 6 PM CHST THURSDAY FOR MPZ001>003.
TYPHOON WARNING FOR MPZ001>003.
MARIANAS WATERS...TROPICAL STORM WARNING FOR PMZ151.
TYPHOON WATCH FOR PMZ151.
TYPHOON WARNING FOR PMZ152>154.
MARIANAS: KLEESCHULTE
EAST MICRONESIA/TROPICAL: DECOU/SCHANK
WEST MICRONESIA: CRUZ/SCHANK
IDSS: MESA
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