380
FXPQ50 PGUM 231919
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
519 AM CHST WED JUN 24 2026
MARIANAS SYNOPSIS
TROPICAL DEPRESSION HIGOS IS MOVING AWAY FROM THE ISLANDS, ENDING THE
POSSIBILITY OF DAMAGING WINDS FOR GUAM, ROTA, TINIAN AND SAIPAN.
COMBINED SEAS OF 5 TO 7 FEET WILL GRADUALLY DIMINISH AS THE WEEK
UNFOLDS.
DISCUSSION
WEATHER IN THE MARIANAS HAS BEEN GRADUALLY TONING DOWN AS TROPICAL
DEPRESSION HIGOS MOVES FARTHER AWAY. COMBINED SEAS ARE DOWN FROM 7 TO
9 FEET EARLIER TO MORE LIKE 5 TO 7 FEET NOW. WINDS OF 20 TO 35 MPH
WITH GUSTS TO 50 MPH ARE NOW 15 TO 20 MPH WITH GUSTS TO 30 MPH, AND
THEY ONLY HAD 0.05 INCHES OF RAIN OVER THE PAST 6 HOURS AT SAIPAN
AIRPORT. SO, CONDITIONS ARE NEARLY BACK TO NORMAL, AND WINDS ARE BACK
TO SOUTHEAST, ALMOST IN THE NORMAL TRADE-WIND DIRECTION. WAS ABLE TO
RECOMBINE THE ZONES AS CONDITIONS NORMALIZE.
MARINE
COMBINED SEAS AND WINDS ARE DIMINISHING AND TURNING TOWARD NORMAL
DIRECTIONS. THESE TRENDS WILL CONTINUE OVER THE NEXT DAY OR SO UNTIL
MARINE CONDITIONS HAVE FULLY NORMALIZED. COMBINED SEAS HAVE
ESSENTIALLY NORMALIZED ALREADY, AND WINDS ARE ABOUT TO FINISH.
FIRE WEATHER
GUAM INTERNATIONAL AIRPORT RECEIVED 0.13 INCHES OF RAIN YESTERDAY.
THIS ALLOWED THE KEETCH-BYRAM DROUGHT INDEX TO RISE A LITTLE TO 245.
THIS IS IN THE LOW FIRE DANGER RANGE, AND THE FIRE DANGER SHOULD
REMAIN LOW FOR AT LEAST THE NEXT 3 OR 4 DAYS.
TROPICAL SYSTEMS
TROPICAL DEPRESSION HIGOS IS CENTERED NEAR 14.8N AND 143.9E. IN
ADDITION TO HAVING WEAKENED, WHICH REMOVED THE THREAT OF DAMAGING
WINDS, IT HAS BEEN SLOWLY PULLING AWAY FROM TINIAN AND SAIPAN. IT IS
EXPECTED TO INTENSIFY AGAIN NOW, BUT ONLY SLOWLY, AND TURN FROM
MOVING WEST TO MOVING NORTHWEST. THIS WILL BRING IT SOUTH OF JAPAN,
WHERE IT WILL RECURVE NORTHEAST TO FINALLY PASS EAST OF JAPAN AS IT
UNDERGOES EXTRATROPICAL TRANSITION TO BECOME A MID-LATITUDE CYCLONE.
FOR FURTHER INFORMATION ON HIGOS, PLEASE REFER TO EITHER THE TROPICAL
CYCLONE WARNING FROM THE JOINT TYPHOON WARNING CENTER UNDER WMO
HEADER WTPN32 PGTW, OR THE TROPICAL CYCLONE PUBLIC ADVISORY FROM THE
NATIONAL WEATHER SERVICE UNDER WMO HEADER WTPQ32 PGUM.
EASTERN MICRONESIA
THE NEAR-EQUATORIAL TROUGH (NET) CONTINUES TO BE THE MAIN WEATHER
FEATURE ACROSS EASTERN MICRONESIA. SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS WILL PREVAIL THROUGH THE REST OF THE WEEK, WITH MAJURO
POTENTIALLY REACHING LOW-END NUMEROUS COVERAGE TODAY (60%). LOCALLY
HEAVY RAIN WILL BE POSSIBLE WITH ANY HEAVIER SHOWERS AND
THUNDERSTORMS TODAY AT MAJURO. WINDS WILL REMAIN LIGHT TO GENTLE AT
KOSRAE AND POHNPEI OVER THE NEXT SEVERAL DAYS AND GENTLE TO MODERATE
AT MAJURO. COMBINED SEAS OF 4 TO 6 FEET WILL CONTINUE THROUGH THE
REST OF THE WEEK.
WESTERN MICRONESIA
UNSETTLED WEATHER WILL CONTINUE TODAY ACROSS WESTERN MICRONESIA AS
SURFACE CONVERGENCE IS BEING SUPPORTED BY BROAD UPPER-LEVEL TROUGHING
NORTH OF THE REGION. SCATTERED TO NUMEROUS SHOWERS AND ISOLATED
THUNDERSTORMS WILL BE POSSIBLE THROUGH TONIGHT, WITH SHOWERS CHANCES
TOPPING AT AROUND LOW-END NUMEROUS AT YAP TODAY. LOCALLY HEAVY RAIN
WILL BE POSSIBLE AT YAP WITH ANY HEAVIER SHOWERS AND THUNDERSTORMS.
LIGHT TO GENTLE WINDS ARE GENERALLY EXPECTED AT ALL FORECAST POINTS
OVER THE NEXT COUPLE OF DAYS WITH THE POSSIBILITY OF YAP EXPERIENCING
SOME PERIODS OF LOW-END MODERATE WINDS. SEA CONDITIONS WILL CONTINUE
TO REMAIN BENIGN THIS WEEK WITH COMBINED SEAS OF 3 TO 5 FEET
FORECAST FOR THE REMAINDER OF THE WEEK.
PREV DISCUSSION
/ISSUED 647 PM CHST TUE JUN 23 2026/
MARIANAS SYNOPSIS...
TROPICAL STORM HIGOS (08W) IS NOW WNW OF TINIAN AND SAIPAN. VISIBLE
SATELLITE IMAGERY DEPICTS MOSTLY CLOUDY SKIES AND SCATTERED SHOWERS
OVER GUAM AND ROTA, WHILE TINIAN AND SAIPAN HAVE CLOUDY SKIES AND
NUMEROUS SHOWERS, WITH THE HEAVIEST OF SHOWERS AND CONVECTION IN
THEIR WESTERN WATERS. TANAPAG BUOY IS SHOWING 6 TO 8 FEET, WITH
LARGER SEA HEIGHTS EXPECTED AROUND THE CENTER OF TS HIGOS.
DISCUSSION...
AS TROPICAL STORM HIGOS (08W) CONTINUES ITS WNW TREK AWAY FROM THE
MARIANAS, CONDITIONS WILL IMPROVE, POSSIBLY FALLING BELOW TROPICAL
STORM CONDITIONS STARTING AROUND MIDNIGHT TONIGHT. UNTIL THEN,
TROPICAL STORM FORCE WINDS ARE TO BE EXPECTED FOR TINIAN AND SAIPAN,
WHILE WINDS OVER ROTA AND GUAM WILL MAINTAIN SPEEDS OF 10 TO 15 MPH,
SHIFTING FROM THE NORTHWEST TO SOUTH AROUND MIDNIGHT. TRAILING
CONVERGENCE AND SOUTHERLY FLOW INTO TS HIGOS WILL KEEP THE MARIANAS
IN A WETTER PATTERN, SO HIGH-END SCATTERED SHOWERS ARE TO BE EXPECTED
ON WEDNESDAY, TAPERING DOWN WEDNESDAY NIGHT. A BRIEF LULL IN SHOWER
ACTIVITY MAY OCCUR BEFORE A SURFACE TROUGH AND TRADE-WIND SURGE
ENVELOP THE REGION LATER IN THE WEEK. A WEAK UPPER-LEVEL LOW MAY
ALSO SET ITS EYES ON THE MARIANAS, SO THUNDERSTORM POTENTIAL COULD
INCREASE DURING THIS TIME PERIOD.
MARINE...
COMBINED SEAS OF 4 TO 5 FT FOR GUAM AND ROTA WILL INCREASE TO 5 TO 6
FT STARTING TOMORROW AS THE COMBINED IMPACTS OF TS HIGOS AND A
TRADE-WIND SURGE UPSTREAM REINVIGORATE THE EAST SWELL THROUGHOUT THE
WEEK. AS FOR TINIAN AND SAIPAN, SEAS ARE MOST LIKELY BETWEEN 9 TO 13
FT CLOSER TO THE CENTER OF TS HIGOS, WITH HEIGHTS EXPECTED TO DROP
TO 6 TO 8 FT STARTING WEDNESDAY ACROSS BOTH COASTAL WATERS, POSSIBLY
EVEN LATER TONIGHT. THERE IS A MODERATE RISK OF RIP CURRENTS ALONG
EAST-FACING REEFS FOR THE MARIANAS AT LEAST FOR THE NEXT FEW DAYS,
AS WELL AS A MODERATE RISK OF LIGHTNING. THE WEST SWELL MAY INCREASE
BY A FOOT LATER IN THE WEEK.
TROPICAL SYSTEMS...
INVEST 94W FROM YESTERDAY, WHICH WAS RATED AT MEDIUM FOR
DEVELOPMENTAL POTENTIAL BY JTWC, BECAME A TCFA (TROPICAL CYCLONE
FORMATION ALERT) LAST NIGHT, AND THEN IT STRENGTHENED TO TROPICAL
STORM HIGOS (08W) THIS MORNING. HIGOS HAS A HISTORY OF TAKING "A
DIFFERENT PATH" THAN EARLIER MODEL GUIDANCE SUGGESTED, HAVING
STRENGTHENED FASTER THAN ANTICIPATED. OVER THE LAST 9 HOURS, HIGOS
TRACKED WEST AND HAS PASSED SOUTH OF TINIAN, VERSUS PASSING NORTH OF
SAIPAN AS PREVIOUSLY ANTICIPATED. TS HIGOS IS LOCATED 40 MILES WEST-
SOUTHWEST OF TINIAN, AND 50 MILES WEST-SOUTHWEST OF SAIPAN. IT'S
FORECASTED TO CONTINUE STRENGTHENING THROUGH THURSDAY, BECOMING A
STRONG TROPICAL STORM (STS), AND POSSIBLY A WEAK TYPHOON.
FOR MORE INFORMATION PLEASE REFER TO BULLETINS FROM THE JOINT
TYPHOON WARNING CENTER UNDER WMO HEADER WTPN32 PGTW AND FROM
THE NATIONAL WEATHER SERVICE UNDER WMO HEADER WTPQ32 PGUM.
EASTERN MICRONESIA...
THE NEAR-EQUATORIAL TROUGH (NET) HAS BECOME MORE "ENERGIZED" TODAY,
AS INCREASING SURFACE CONVERGENCE HAS LED TO GREATER CONVECTIVE
COVERAGE THIS AFTERNOON, WITH THE LATEST SATELLITE AND NUMERICAL DATA
SUGGESTING THIS TREND WILL CONTINUE FOR AT LEAST THE REMAINDER OF
THIS WEEK, AND POSSIBLY INTO THE FIRST HALF OF NEXT WEEK, WITH AN
EVENTUALLY DECREASING RAINFALL POTENTIAL FROM EAST TO WEST
COMMENCING. FOR NOW, WE SENT OUT A FORECAST UPDATE TO ACCOUNT FOR THE
MODEL/SATELLITE TRENDS GIVEN INCREASED FORECASTER CONFIDENCE.
RESIDENTS CAN EXPECT AT LEAST SCATTERED SHOWERS TO CONTINUE AREA-WIDE
FOR THE NEXT FEW DAYS, WITH A FEW PERIODS OF LOCALLY HEAVY RAINFALL
POSSIBLE. AFTER THAT, IT'LL DEPEND ON THE NET ORIENTATION AND IF ANY
TROPICAL DISTURBANCE DEVELOPS.
AS FOR MARINE CONDITIONS, MAINLY LIGHT TO GENTLE WINDS WITH SEAS OF 3
TO 5 FEET WILL CONTINUE THROUGH THE FORECAST PERIOD.
WESTERN MICRONESIA...
A FAIRLY UNSETTLED AND MESSY PATTERN CONTINUES ACROSS THE REGION,
INFLUENCED BY SEVERAL FEATURES. THERE IS A WEAK ANTICYCLONE LOCATED
OVER YAP STATE ROUGHLY WEST-SOUTHWEST OF EAURIPIK, EMBEDDED WITHIN A
BROAD SURFACE RIDGE THAT EXTENDS SOUTHEAST ACROSS MUCH OF THE
REGION FROM YAP AND PALAU TO THE EQUATOR SOUTH OF CHUUK. THIS WOULD
TYPICALLY SUPPORT DRIER WEATHER ACROSS THE REGION, BUT MOIST
CONVERGENCE WITHIN THE RIDGE IS DEVELOPING BANDS OF SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS, LIKELY SUPPORTED BY A BROAD
UPPER-LEVEL TROUGH JUST NORTH OF THE AREA. THIS UPPER TROUGH SITS
OVER A BROAD MONSOON-LIKE SURFACE TROUGH THAT BRIDGES TY MEKKHALA AND
TS HIGOS, WITH INCREASED CONVERGENCE IN THE WIND FIELD JUST SOUTHWEST
OF TS HIGOS AND THE MARIANAS. THIS WILL KEEP MOST OF THE SHOWERS AND
THUNDERSTORMS FARTHER NORTH NEAR YAP PROPER FOR TONIGHT, WHILE PALAU
CAN EXPECT DRYING CONDITIONS OVERNIGHT.
THE BROAD SURFACE RIDGE WILL GRADUALLY WEAKEN AND RETREAT SOUTH
THROUGHOUT THE WEEK, ALLOWING THE EXTENSIVE SURFACE TROUGH TO THE
NORTH TO GRADUALLY REORGANIZE OVER THE AREA AS TY MEKKHALA AND TS
HIGOS MOVE FAR AWAY. WEAK DISTURBANCES AND CONVERGENCE WITHIN THIS
ENVIRONMENT WILL MAINTAIN SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS NEAR PALAU AND YAP THROUGHOUT THE WEEK, WITH A GENERAL
TREND OF HIGHER SHOWER COVERAGE NEAR YAP PROPER.
FAR TO THE EAST, CHUUK IS SITUATED WITHIN THE BROAD SURFACE TROUGH
EXTENDING SOUTHEAST FROM TS HIGOS, WITH AN AREA OF SCATTERED TO
NUMEROUS SHOWERS LOCATED WITHIN THE CONVERGENCE BOUNDARY SOUTH OF
WENO. CHUUK CAN EXPECT PERIODS OF AT LEAST SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS THROUGHOUT THE REST OF THE WEEK AS IT REMAINS
IN THIS UNSETTLED PATTERN, WITH A PEAK ON WEDNESDAY AND WEDNESDAY
NIGHT AS THE TRAILING CONVERGENCE BEHIND TS HIGOS DEVELOPS SHOWERS
OVERHEAD.
BENIGN SEA CONDITIONS CONTINUE ACROSS THE REGION. LATEST ALTIMETRY
AND YAP BUOY DATA SHOW COMBINED SEAS BETWEEN 3 AND 5 FEET. THERE IS
A PRIMARY WEST TO SOUTHWEST SWELL FOR YAP, AND A MIXED LIGHT SWELL
FROM THE SOUTHWEST AND EAST TO SOUTHEAST FOR PALAU. FOR CHUUK, THERE
REMAINS A PRIMARY SOUTHEAST TO EAST SWELL, WITH A LIGHT SECONDARY
SWELL OUT OF THE NORTHEAST.
GUM WATCHES/WARNINGS/ADVISORIES
GU...NONE.
MP...NONE.
MARIANAS WATERS...NONE.
MARIANAS: STANKO
EAST/WEST MICRONESIA: WHISNANT
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