335
AXPQ20 PGUM 090100
TWDPQ
TROPICAL WEATHER DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
1100 AM CHST TUE SEP 9 2025
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
NONE.
..OTHER WEATHER SYSTEMS
SURFACE TROUGHS...
A PAIR OF WESTWARD-MOVING SURFACE TROUGHS IS SEEN WITHIN THE ITCZ
AND ARE ACTING TO CONSOLIDATE HEAVY SHOWERS AND THUNDERSTORMS OVER
CHUUK AND KOSRAE STATES AND THE SOUTHERN MARSHALL ISLANDS. SEE THE
ITCZ SECTION, BELOW, FOR MORE INFORMATION ON THESE TROUGHS AND THE
ITCZ.
SURFACE CIRCULATION...
A WEAK LOW-LEVEL CIRCULATION HAS FORMED IN THE NORTHERN PHILIPPINE
SEA AT 23N141E. THIS CIRCULATION IS THE OFFSHOOT OF THE FAR WESTERN
END OF THE WEAKENING STATIONARY FRONT. FAVORABLE UPPER-LEVEL WINDS
ALOFT ARE HELPING TO SPARK SCATTERED SHOWERS AND THUNDERSTORMS,
INCLUDING A NOTABLE AMOUNT OF LIGHTNING, BETWEEN 20N AND 24N FROM
135E TO 143E. CONVECTION WILL PERSIST THE NEXT 12-24HR AS THE
CIRCULATION HEADS WEST, EVENTUALLY OPENING INTO A SURFACE TROUGH.
TUTT CIRCULATIONS...
UPPER-LEVEL CIRCULATIONS ARE FOUND NORTH OF THE MARIANAS NEAR 21N146E
AND NORTHEAST OF WAKE NEAR 22N170E. THE FIRST IS HELPING TO SPARK A
FEW THUNDERSTORMS NEAR SAIPAN, WHILE THE SECOND IS INTERACTING WITH A
SUBTLE SURFACE TROUGH TO GENERATE WIDESPREAD SHOWERS AND
THUNDERSTORMS EAST-NORTHEAST OF WAKE ISLAND BETWEEN 19N AND 25N FROM
169E TO 175E. THESE TWO UPPER LOWS WILL CONTINUE TO DRIFT WEST. THE
MARIANAS UPPER LOW WILL LIKELY CONTINUE SPARKING BRIEF THUNDERSTORMS
IN ITS PERIPHERY IN THE OPEN PHILIPPINE SEA, WHILE THE WAKE ISLAND
UPPER LOW WILL LIKELY CONTINUE TO GENERATE WIDESPREAD SHOWERS AND
THUNDERSTORMS AS IT DRIFTS IN TANDEM WITH THE SURFACE DISTURBANCE.
THESE SHOWERS AND THUNDERSTORMS WILL GENERALLY STAY NORTH OF WAKE
ISLAND, THOUGH SHORTER PERIODS OF SHOWERS AND THUNDERSTORMS WILL BE
POSSIBLE THROUGH MIDWEEK.
STATIONARY FRONT...
THE STATIONARY FRONT HAS RETREATED TO THE NORTH OF THE GUAM AOR DUE
TO A STRENGTHENING HIGH PRESSURE RIDGE IMMEDIATELY TO ITS SOUTH.
OTHER SYSTEMS...
..ITCZ
HEAVY SHOWERS AND THUNDERSTORMS HAVE INCREASED IN COVERAGE ACROSS
CENTRAL AND EASTERN MICRONESIA ALONG THE ITCZ. CONVECTION SPANS
FROM EASTERN YAP STATE TO MAJURO, GENERALLY BETWEEN 3N AND 11N. THE 2
WESTWARD-MOVING SURFACE TROUGHS NOTED ABOVE ARE HELPING TO
CONSOLIDATE SHOWERS AND THUNDERSTORMS JUST WEST OF CHUUK, NEAR
KOSRAE, AND JUST SOUTH OF KWAJALEIN. RECENT OBSERVATIONS OUT OF CHUUK
SHOW A 3HR RAIN ACCUMULATION OF NEARLY 1.5IN. WHILE WIND OBSERVATIONS
SHOW GENTLE TO MODERATE WINDS, SATELLITE-DERIVED DATA SHOWS PATCHES
OF 15-20 MPH WINDS SUGGESTING HEAVY CONVECTIVE COULD BE CAPABLE OF
GUSTS OF 25-30 MPH. OVER THE NEXT COUPLE OF DAYS, THE BROADER
CLUSTER OF CONVECTION ACROSS CHUUK STATE WILL CONTINUE WESTWARD
TOWARD YAP AND PALAU, WHILE THE SHOWERS AND THUNDERSTORMS FARTHER
EAST GRADUALLY DIMINISHES WHILE PUSHING TO THE WEST-NORTHWEST.
AYDLETT
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