900
FXPQ50 PGUM 210641
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
441 PM CHST WED OCT 21 2026
MARIANAS SYNOPSIS
GENTLE TO MODERATE NORTHEASTERLIES PREVAIL ACROSS THE MARIANAS.
SATELLITE IMAGERY AND DOPPLER RADAR INDICATE A FEW SHOWERS MAKING
THEIR WAY ACROSS THE COASTAL WATERS FROM THE NORTHEAST. MOST RECENT
ALTIMETRY PASSES INDICATE 6 TO 8 FOOT SEAS TO THE EAST OF THE REGION.
DISCUSSION
A MOSTLY DRY TRADE-WIND PATTERN IS EXPECTED THROUGH THURSDAY, AS THE
RIDGE FROM PREVIOUS DAYS BEGINS TO EXIT TO THE WEST FOLLOWING DISTANT
STY CHAMPI. AFTER, A TRADE-WIND TROUGH COMING IN FROM THE EAST-
NORTHEAST IS EXPECTED TO MOVE IN, BRINGING LOW-END PATCHY SHOWERS
AND SOME THUNDERSTORMS ENHANCED BY THE PINCHING BETWEEN THE SUBTROPICAL
RIDGE TO THE NORTH, AND BUILDING TROPICAL DISTURBANCES TO THE
SOUTHEAST. A RETURN OF ANOTHER TROPICAL RIDGE SPANNING FROM PALAU IS
LIKELY DURING THE WEEKEND, BRINGING ANOTHER PERIOD OF DRIER
CONDITIONS BEGINNING SUNDAY.
MARINE
COMBINED
SEAS OF 6 TO 8 FEET ARE EXPECTED THROUGH AT LEAST THURSDAY, TO THEN
BRIEFLY INCREASE A FOOT THURSDAY NIGHT AS THE HIGHEST PULSE OF THE
NORTHEASTERLY SWELL ARRIVES THEN. SEAS LOOK TO DIMINISH THEREAFTER AS
THIS SWELL BEGINS TO WEAKEN. A MODERATE RISK OF RIP CURRENTS IS
EXPECTED ALONG NORTH, EAST, AND WEST FACING REEFS OF THE MARIANAS FOR
MUCH OF THIS WEEK DUE TO A STRENGTHENING NORTHEASTERLY SWELL, AND A
SECONDARY WESTERLY SWELL PRODUCED BY DISTANT STY CHAMPI.
TROPICAL SYSTEMS
AT 100 PM CHST, THE CENTER OF SUPER TYPHOON CHAMPI WAS LOCATED NEAR
18N130E ALONG THE NORTHWESTERNMOST EDGE OF THE REGION. CHAMPI IS
MOVING WEST-NORTHWEST AT 17 MPH, AND THEN EXPECTED TO MAKE A SLIGHT
TURN TOWARD THE NORTHWEST WITH A DECREASE IN FORWARD SPEED THROUGH
THURSDAY. MAXIMUM SUSTAINED WINDS HAVE DECREASED TO 180 MPH. CHAMPI
IS FORECAST TO WEAKEN THROUGH TONIGHT, BUT WILL REMAIN A MAJOR
TYPHOON AS IT CONTINUES HEADING TOWARD TAIWAN, BEFORE RECURVING
TOWARD THE RYUKYU ISLANDS. THIS MEANS THAT THE SYSTEM HAS LEFT NWS
GUAM'S AREA OF RESPONSIBILITY (AOR).
FOR MORE INFORMATION, SEE BULLETINS ISSUED BY THE JOINT TYPHOON
WARNING CENTER UNDER WMO HEADER WTPN32 PGTW AND BY THE NATIONAL
WEATHER SERVICE UNDER WMO HEADER WTPQ32 PGUM.
EASTERN MICRONESIA
THE MONSOON TROUGH FRAGMENT REMAINS ACTIVE OVER EASTERN MICRONESIA,
PRIMARILY SOUTH OF THE MAIN FORECAST POINTS. IT IS EXPECTED TO
PRODUCE SCATTERED SHOWERS AND POSSIBLY ISOLATED THUNDERSTORMS AT ALL
THREE LOCATIONS TONIGHT. CONVECTION LOOKS TO LINGER OVER MAJURO
THROUGH THURSDAY AND AT POHNPEI THROUGH THURSDAY NIGHT, WITH KOSRAE
SEEING DRIER CONDITIONS BY THURSDAY MORNING. AFTER THESE SHOWERS
MOVE OUT, EXPECT A DRY PATTERN FOR ALL THREE FORECAST POINTS THAT
WILL LIKELY CONTINUE THROUGH THE BEGINNING OF NEXT WEEK. DURING THE
TIME, THE MONSOON TROUGH LOOKS TO REORGANIZE AND LINK UP WITH A
DEVELOPING MONSOON TROUGH OVER WESTERN MICRONESIA.
FOR THE MARINE FORECAST, FAIRLY BENIGN CONDITIONS WILL CONTINUE FOR
THE NEXT SEVERAL DAYS, WITH MOSTLY LIGHT TO GENTLE WINDS AND SEAS
BETWEEN 3 AND 5 FEET. POHNPEI AND MAJURO WILL SEE OCCASIONAL
MODERATE WINDS THE NEXT DAY OR TWO.
WESTERN MICRONESIA
AS CHAMPI CONTINUES TO MOVE OFF TO THE WEST-NORTHWEST, WINDS AND SEAS
CONTINUE TO SLOWLY SUBSIDE AT PALAU AND YAP. UNFORTNATELY, AS A
RIDGE OF HIGH PRESSURE MOVES SLOWLY WEST, ISOLATED SHOWERS ARE THE
MOST THAT WE CAN HOPE FOR RAINFALL WISE. LIGHT TO GENTLE WINDS WILL
PREVAIL THROUGH THE FORECAST PERIOD.
FURTHER EAST AT CHUUK, A WEAK DISTURBANCE LOCATED JUST TO YOUR SOUTH
HAS PLENTY OF CONVECTION ASSOCIATED WITH IT, MAINLY ACROSS THE
SOUTHEASTERN SEMICIRCLE (THE NORTHEAST THROUGH SOUTHEAST THROUGH
SOUTHWEST REGIONS). SOME OF THIS CONVECTION FEATURES HEAVY RAINFALL,
AS EVIDENT BY CLOUD TOP TEMPERATURES SURPASSING -80 C. THE
CIRCULATION IS NOT FORECAST TO DEVELOP INTO A TROPICAL CYCLONE, BUT
IT WILL DRIFT NORTH-NORTHWEST THE NEXT 60 HOURS OR SO. THIS WILL
BRING MAINLY SCATTERED SHOWERS TO CHUUK, BUT A PERIOD OF LOCALLY
HEAVY RAINFALL ASSOCIATED WITH NUMEROUS SHOWERS IS ALREADY IN THE
FORECAST FOR THURSDAY, AND THIS MAY NEED TO BE EXTENDED AS THE
DISTURBANCE TAKES IT'S TIME CROSSING THE AREA.
MODERATE TO GENTLE WINDS AND A BRIEF INCREASE IN WAVE HEIGHT WILL
OCCUR AS IT MOVES THROUGH THE AREA. AFTER THAT, WINDS AND WAVES WILL
DIMINISH. HOWEVER, A STRENGTHENING SOUTHWEST MONSOON FLOW WILL KEEP
SCATTERED SHOWERS GOING INTO EARLY NEXT WEEK.
GUM WATCHES/WARNINGS/ADVISORIES
GU...NONE.
MP...NONE.
MARIANAS WATERS...NONE.
MARIANAS/TROPICAL: MONTVILA
EAST MICRONESIA: KLEESCHULTE
WEST MICRONESIA: DOLL
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