706  
FXPQ50 PGUM 012046  
AFDGUM  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE TIYAN GU  
646 AM CHST WED JUL 2 2025  
   
MARIANAS UPDATE  
 
INCREASED THE CLOUDS A LITTLE, AS SATELLITE SHOWS THE OUTER CLOUDS  
IN THE MONSOON BAND MOVING THROUGH THE FORECAST ZONES. ALSO LOWERED  
THE COMBINED SEAS/WAVE HEIGHTS LOOKING AT THE BUOYS AND THE ECMWFWAVE  
MODEL DATA. THIS HAD THE EFFECT OF LOWERING BOTH THE EAST AND THE  
SOUTHWEST SWELLS, WHICH MADE THE RISK OF RIP CURRENTS LOW.  
 
 
   
TROPICAL SYSTEMS  
 
TROPICAL DEPRESSION 04W, FORMERLY MONSOON DISTURBANCE INVEST 90W, IS  
CENTERED NEAR 25N147E, MOVING NORTH TO NORTHWEST AT 9 MPH. AT THIS  
TIME, MAXIMUM SUSTAINED WINDS ARE 35 MPH NEAR THE CENTER. 04W IS  
FORECAST TO INTENSIFY THROUGH TONIGHT, POSSIBLY BECOMING A TROPICAL  
STORM AS IT EXITS THE REGION SOMETIME THIS AFTERNOON. NO DIRECT  
IMPACTS ARE EXPECTED TO THE MARIANAS OR MICRONESIA FROM THIS STORM.  
 
 
   
EASTERN MICRONESIA UPDATE  
 
ISOLATED TO SCATTERED SHOWERS ARE SEEN ACROSS THE REGION. ONLY MINOR  
ADJUSTMENTS WERE MADE WITH THIS FORECAST PACKAGE. THE MAIN CHANGES  
WERE TO DELAY THE START OF SCATTERED SHOWERS FOR KOSRAE AND POHNPEI.  
KOSRAE CURRENTLY SITS IN BETWEEN SCATTERED SHOWERS AND ISOLATED  
THUNDERSTORMS LOCATED TOWARDS THE NORTH AND SOUTH. THESE SHOWERS AND  
THUNDERSTORMS ARE FORECAST TO INCREASE IN COVERAGE LATER TODAY AS  
SURFACE CONVERGENCE FROM THE FRAGMENTED ITCZ AND A TRADE-WIND TROUGH  
MOVE OVER KOSRAE. POHNPEI HAS SEEN A DECREASE IN SHOWERS THIS  
MORNING, BUT GUIDANCE SHOWS A RESURGENCE THIS AFTERNOON DUE TO A  
TRADE-WIND TROUGH MOVING THROUGH. SCATTERED SHOWERS WERE KEPT FOR  
MAJURO THROUGH THE DAY AS SATELLITE SHOWS INCREASING COVERAGE OF WEAK  
SHOWERS ACROSS THE RMI.  
 
ONLY MINOR EDITS WERE MADE TO THE MARINE FORECAST. SWELLS WERE  
BUMPED DOWN A FOOT FOR TODAY TO AROUND 5 TO 6 FEET. POHNPEI'S BUOY  
SHOWS THAT A GOOD PORTION OF THE SEA HEIGHT IS FROM WIND WAVE, AND A  
6 FOOT SWELL MAY BE ON THE HIGH SIDE RIGHT NOW.  
 
 
   
WESTERN MICRONESIA UPDATE  
 
SATELLITE SHOWS NUMEROUS SHOWERS SOUTHEAST OF PALAU AND SCATTERED  
SHOWERS JUST SOUTHEAST OF CHUUK. ONLY MINOR CHANGES WERE MADE WITH  
THIS UPDATE. THE MAIN ONE WAS TO START YAP WITH ISOLATED SHOWERS AND  
THUNDERSTORMS. MODELS DO SHOW SCATTERED SHOWERS AND ISOLATED  
THUNDERSTORMS MOVING INTO YAP LATER TODAY. THE SCATTERED SHOWERS  
WERE KEPT FOR PALAU AND CHUUK TODAY. FOR PALAU, NUMEROUS SHOWERS AND  
THUNDERSTORMS ARE SEEN WELL TO THE SOUTHEAST, HOWEVER SOME  
CONVECTION ON THE NORTHERN EDGE OF THE DEEP CONVECTION LOOKS TO MOVE  
INTO THE COASTAL WATERS IN A FEW HOURS, THIS WOULD BRING SCATTERED  
SHOWERS, WITH ADDITIONAL SHOWERS EXPECTED THROUGHOUT THE DAY. FOR  
CHUUK, SCATTERED SHOWERS ARE SEEN JUST TO THE EAST OF WENO WITH A  
STRONGER SHOWER JUST SOUTHEAST OF THE COASTAL WATERS. GUIDANCE WAS  
IN GOOD AGREEMENT WITH INCREASING SHOWER COVERAGE BY 00Z.  
 
NO CHANGES WERE MADE TO THE MARINE FORECAST.  
 
 
   
PREV DISCUSSION  
/ISSUED 544 PM CHST TUE JUL 1 2025/  
 
MARIANAS SYNOPSIS...  
SATELLITE IMAGERY AND RADAR SHOW ISOLATED SHOWERS FOR GUAM AND ROTA  
AND SCATTERED SHOWERS FOR TINIAN AND SAIPAN. ALTIMETRY SHOWS COMBINED  
SEAS OF 3 TO 5 FEET, WHILE IPAN AND RITIDIAN BUOYS SHOW HEIGHTS OF 3  
TO 4 FEET.  
 
DISCUSSION...  
SCATTERED SHOWERS ARE SEEN JUST OUTSIDE THE MARIANAS WATERS. THESE  
SHOWERS ARE ANTICIPATED TO BUILD IN OVERNIGHT FOR MUCH OF CNMI, GUAM  
IS EXPECTED TO REMAIN IN A CLEARER REGION. A BREAK IN THE MONSOON  
TROUGH WILL GIVE WAY TO A DRIER NEXT FEW DAYS. SHOWERS ARE  
ANTICIPATED TO PICK BACK UP AROUND THE END OF THE WORKWEEK. OVER THE  
WEEKEND, SHOWERS ARE ANTICIPATED TO BE MINIMAL.  
 
MARINE...  
BENIGN SEA CONDITIONS ARE ANTICIPATED THROUGHOUT THE FORECAST  
PERIOD. WINDS ARE EXPECTED TO BE LIGHT TO GENTLE. SURF IS THE HIGHEST  
ALONG EAST FACING REEFS. AN INCOMING SOUTHWESTERLY SWELL IS  
ANTICIPATED TO ARRIVE OVER THE WEEKEND. THIS MAY INCREASE SURF AND  
RIP CURRENT RISK ALONG SOUTH AND WEST FACING REEFS. THE RISK OF RIP  
CURRENTS REMAINS MODERATE ALONG EAST FACING REEFS.  
 
TROPICAL SYSTEMS...  
JTWC'S (JOINT TYPHOON WARNING CENTER) INVEST 90W, CURRENTLY SHOWING  
A DEFINED CIRCULATION CENTER, BUT IS ROUGHLY LOCATED WELL NORTH-  
NORTHEAST OF SAIPAN NEAR 22.5N 148.2E, MOVING NORTHWARD. NUMEROUS  
SHOWERS AND ISOLATED THUNDERSTORMS ARE FOUND TO THE EAST OF THE  
INVEST. 90W IS NOW RATED LOW, MEANING IT IS EXPECTED TO DEVELOP, BUT  
NOT EXPECTED TO BECOME A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT  
24 HOURS. ALTHOUGH A CLOSED CIRCULATION IS NOT SEEN NOW, 90W IS  
BECOMING MORE ORGANIZED, WITH A TUTT CELL NEAR 21N145E PROVIDING  
DIVERGENT FLOW IN THE UPPER LEVELS. MODELS DO FAVOR 90W DEVELOPING  
INTO A MORE ORGANIZED CIRCULATION AS IT CONTINUES NORTH. FOR MORE  
INFORMATION ON INVEST 90W, SEE BULLETINS ISSUED BY JTWC UNDER WMO  
HEADER ABPW10 PGTW.  
 
EASTERN MICRONESIA...  
FOR NOW, THE INTER-TROPICAL CONVERGENCE ZONE (ITCZ) HAS WEAKENED A  
BIT, WITH LESS CONVECTION SEEN ALONG THE BOUNDARY. THERE IS A FLARE  
UP OF CONVECTION WITH A TRADE-WIND TROUGH THAT IS MOVING TOWARD  
KOSRAE. THIS TROUGH LOOKS TO BRING INCREASED CONVECTION TO KOSRAE  
LATER THIS EVENING. ANOTHER WEAK TROUGH IS SEEN APPROACHING POHNPEI  
AND IS EXPECTED TO BRING LOW-END SCATTERED SHOWERS AND POSSIBLE  
THUNDERSTORMS TO POHNPEI BY MIDNIGHT. OTHERWISE, THE ITCZ IS EXPECTED  
TO STRENGTHEN A BIT, WITH INCREASING SHOWERS SPREADING ACROSS THE  
REGION. AN OVERALL UNSETTLED PATTERN LOOKS LIKELY FOR THE REGION AS  
THE ITCZ STRENGTHENS AND WEAK TRADE-WIND TROUGHS MOVE THROUGH. THERE  
WILL BE BRIEF PERIODS OF ISOLATED SHOWERS THROUGH THE WEEK DUE TO THE  
WAVERING OF THE ITCZ AND IN BETWEEN TROUGHS MOVING THROUGH.  
 
NO CHANGES WERE MADE TO THE MARINE FORECAST. COMBINED SEAS OF 5 TO 7  
FEET AT MAJURO SLOWLY SUBSIDING OVER THE NEXT FEW DAYS, DROPPING TO  
BETWEEN 3 AND 5 FEET FOR THE WEEKEND. SEAS OF 4 TO 6 FEET FOR KOSRAE  
AND POHNPEI COULD REACH 5 TO 7 FEET TONIGHT INTO WEDNESDAY BEFORE  
SUBSIDING TO BETWEEN 3 AND 4 FEET FOR THE WEEKEND. GENTLE TO MODERATE  
WINDS ARE EXPECTED THROUGH THE WEEK FOR KOSRAE AND MAJURO, WITH  
GENTLE TO MODERATE WINDS BECOMING LIGHT TO GENTLE FOR POHNPEI  
WEDNESDAY NIGHT.  
 
WESTERN MICRONESIA...  
THE WET, SOUTHWESTERLY MONSOON PATTERN LOOKS TO CONTINUE FOR TONIGHT  
WITH ROUNDS OF HEAVIER SHOWERS AND THUNDERSTORMS FOR BOTH YAP AND  
PALAU. COULD SEE FRESH TO POTENTIALLY STRONG GUSTS WITH THE BURSTS OF  
SHOWERS. A SURFACE RIDGE WILL TRY TO CREEP WEST AND MAY PUSH THE  
EDGE OF THE MONSOON FLOW TO THE NORTH AND WEST OF PALAU AND YAP, WITH  
GENERALLY ISOLATED TO LOW-END SCATTERED SHOWERS EXPECTED THROUGH THE  
END OF THE WEEK. THROUGH THE WEEKEND INTO EARLY NEXT WEEK, MAY SEE  
THE RIDGE BREAK DOWN OVER THE REGION AND A SLOW RETURN TO A WETTER,  
MONSOON-LIKE PATTERN.  
 
OUTSIDE OF GUSTY WINDS AND CHOPPY SEAS NEAR HEAVIER SHOWERS AND  
THUNDERSTORMS, FAIRLY BENIGN MARINE CONDITIONS EXPECTED, WITH SEAS 3  
TO 5 FEET AND GENTLE TO AT TIMES MODERATE WINDS WILL DIMINISH  
SLIGHTLY OVER THE COMING DAYS AS THE MONSOON SWELL AND WINDS  
DECREASE. BY LATE WEEKEND INTO EARLY NEXT WEEK, A LONGER-PERIOD  
NORTHWEST SWELL GENERATED BY A POSSIBLE DISTANT TROPICAL CYCLONE  
DEVELOPING NORTHEAST OF THE PHILIPPINES COULD BUILD INTO THE REGION,  
INCREASING SEAS ANS SURF.  
 
FOR CHUUK, A SURFACE TROUGH LIFTING NORTHWEST ALONG THE LEADING EDGE  
OF A BUILDING ITCZ WILL BRING INCREASING SHOWERS OVER THE COMING  
DAYS. EXPECT ISOLATED SHOWERS THIS EVENING TO BECOME SCATTERED AFTER  
MIDNIGHT. HIGH-END SCATTERED TO NUMEROUS SHOWERS AND ISOLATED  
THUNDERSTORMS ARE EXPECTED WEDNESDAY THROUGH THURSDAY AS THE  
AFOREMENTIONED FEATURES PASS THROUGH. WHILE COVERAGE LOOKS TO  
DIMINISH BEYOND THURSDAY AS THE TROUGH PUSHES AWAY AND THE ITCZ  
DIMINISHES, ARE STILL EXPECTING SCATTERED SHOWERS AND ISOLATED  
THUNDERSTORMS INTO THE WEEKEND AS SUBTLE SURFACE FEATURES PASS  
THROUGH AND WEAK EAST-SOUTHEAST FLOW LINGER.  
 
GENTLE TO MODERATE WINDS ARE EXPECTED THROUGH THURSDAY. FRESH TO  
POTENTIALLY STRONG GUSTS ARE POSSIBLE NEAR HEAVIER SHOWERS AND  
THUNDERSTORMS AS WELL. WINDS LOOK BECOME LIGHT TO GENTLE BY FRIDAY AS  
THE TROUGH PUSHES WEST. SEAS OF 4 TO 6 FEET WILL BE POSSIBLE THROUGH  
THURSDAY NIGHT WITH THE DISTURBANCE PUSHING THROUGH, THEN LOWERING  
AROUND 2 FEET BY THE WEEKEND.  
 
 
   
GUM WATCHES/WARNINGS/ADVISORIES  
 
GU...NONE.  
MP...NONE.  
MARIANAS WATERS...NONE.  
 
 
 
 
MARIANAS UPDATE: STANKO  
TROPICAL UPDATE: MONTVILA  
EAST/WEST MICRONESIA UPDATE: WILLIAMS  
MARIANAS: BOWSHER  
EAST MICRONESIA: KLEESCHULTE  
WEST MICRONESIA: SLAGLE  
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