613
AXPQ20 PGUM 230958 AAA
TWDPQ
TROPICAL WEATHER DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE TIYAN GU
758 PM CHST WED JUL 23 2025
UPDATED TO INCLUDE THE TROPICAL CYCLONE FORMATION ALERT (TCFA)
FOR INVEST 98W
TROPICAL WEATHER DISCUSSION FOR THE WESTERN NORTH PACIFIC BETWEEN
THE EQUATOR AND 25N FROM 130E TO 180. THE FOLLOWING INFORMATION IS
BASED ON RECENT SATELLITE IMAGERY/DATA, WEATHER OBSERVATIONS, RADAR,
AND METEOROLOGICAL ANALYSIS.
..SPECIAL FEATURES
TROPICAL CYCLONES...
TROPICAL STORM (TS) FRANCISCO (10W) HAS EXITED WEST OF OUR AREA
OF RESPONSIBILITY (AOR). NO DIRECT IMPACTS FROM TS FRANCISCO WILL
BE FELT ACROSS THE MARIANAS OR MICRONESIA.
TROPICAL AND MONSOON DISTURBANCES...
THE TROPICAL DISTURBANCE KNOWN AS JTWC INVEST 98W IS CURRENTLY
LOCATED NEAR 12.9N, 145.0E. INVEST 98W HAS BEEN UPGRADED TO HIGH
BY THE JOINT TYPHOON WARNING CENTER (JTWC), AND A TROPICAL CYCLONE
FORMATION ALERT (TCFA) HAS BEEN ISSUED, MEANING THAT DEVELOPMENT
INTO A SIGNIFICANT TROPICAL CYCLONE (TROPICAL DEPRESSION) IS
EXPECTED WITHIN THE NEXT 24 HOURS. 98W IS FORECASTED TO SLOWLY
DEVELOP AS IT SHIFTS NORTHWEST ONCE IT CROSSES THE SOUTHERN
MARIANAS, LIKELY STAYING TO THE WEST OF TINIAN AND SAIPAN. HEAVY
RAINFALL AND GUSTY WINDS ARE EXPECTED ACROSS THE MARIANAS THE NEXT
SEVERAL DAYS DUE TO INVEST 98W AND THE TRAILING MONSOON SURGE.
FOR MORE INFORMATION ON INVEST 98W (TCFA), SEE BULLETINS ISSUED BY
JTWC UNDER WMO HEADER WTPN21 PGTW.
..OTHER WEATHER SYSTEMS
MONSOON TROUGH...
THE MONSOON TROUGH ENTERS THE REGION AT 20.5N, 130E, OR WHERE TD 10W
IS CURRENTLY LOCATED. THE MONSOON TROUGH THEN EXTENDS SOUTHEASTWARD
TO 9N149E. NUMEROUS SHOWERS AND ISOLATED THUNDERSTORMS ARE SEEN WHERE
THE MONSOON TROUGH AND THE TRADE-WINDS CONVERGE, JUST SOUTH OF THE
MARIANAS. THE MONSOON TROUGH IS FORECASTED TO LIFT NORTHWARD OVER THE
NEXT DAY OR TWO. THE MONSOON TROUGH IS EXPECTED TO INTERACT WITH
INVEST 98W TO BRING HEAVY RAINFALL TO THE MARIANAS.
TRADE-WIND TROUGHS...
A TRADE-WIND TROUGH IS LOCATED NORTHEAST OF WENO AND NORTHWEST OF
POHNPEI, OR FROM 9N155E TO 14N156E. SCATTERED TO NUMEROUS
SHOWERS AND ISOLATED THUNDERSTORMS ARE SEEN ALONG THIS TROUGH. THIS
FEATURE WILL MOVE GENERALLY WESTWARD BEFORE MERGING WITH THE MONSOON
TROUGH TO THE WEST.
TUTT...
A TUTT ENTERS OUR REGION AT 25N155E AND THEN SPLITS SOUTH-SOUTHWEST
TO 12N147E AND EASTWARD TO 25N165E. LITTLE SHOWER ACTIVITY IS SEEN
ALONG THE TUTT. THE TUTT HAS CONTINUED TO WEAKEN AND IS FORECASTED TO
WEAKEN FURTHER OVER THE COMING DAYS.
..ITCZ
THE ITCZ HAS WEAKENED AND FRAGMENTED AND IS EXPECTED TO REMAIN WEAK
OVER THE COMING DAYS. LITTLE ACTIVITY IS SEEN ALONG THE REMNANTS OF
THE ITCZ LOCATED OVER KOSRAE AND POHNPEI.
WILLIAMS/SLAGLE
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