Tropical Weather Discussion
Issued by NWS
Issued by NWS
995 AXPQ20 PGUM 030218 TWDPQ Tropical Weather Discussion National Weather Service Tiyan GU 1218 PM ChST Thu Jul 3 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... MONSOON TROUGH... The monsoon trough enters near 15N130E and extends northeastward north of the northern CNMI and continues northeastward until it exits the region near 25N152E, and into TS Mun (04W). This trough is producing scattered to numerous showers and isolated thunderstorms over the northern CNMI and scattered thunderstorms around 12N132E (far west of Guam and northwest of Palau and Yap). Showers associated with the monsoon trough can be seen as far as 630 miles south of the axis. Heavy showers are possible over the northern CNMI with a modest risk of lightning, and heavy showers and thunderstorms for the area around 12N132E. This feature is expected to move northwestward over the coming days. SURFACE TROUGH... There is a surface trough located between Satawal and Chuuk, starting near 9N149E and extending southwestward to near EQ145E. Shower coverage increases the further south down the axis one travels with the majority of showers near the Equator. A few flashes of lightning have been detected near the Equator. This feature is expected to maintain its intensity and move westwards over the next few days. CONVERGENCE ZONE... There is a convergence zone extending across central Micronesia in the vicinity of Chuuk, Pohnpei, Nukuoro and Kapingamarangi. This feature is producing scattered showers and isolated thunderstorms across the area, mainly along its southern extent near Kapingamarangi. This feature is expected to decay over the coming days. TRADE WIND TROUGH... There is a trade-wind trough located near 10N169E which extends southwest to near 4N163E. This passes over the islands and atolls of Utirik, Wotje, Kwajalein, Ailinglaplap within the RMI and Kosrae. This trough is on the leading edge of the ITCZ (more on that in the ITCZ Section). Showers are observed mainly along and up to 175 miles north of the trough axis. Showers are most pronounced near the northeast and southwest extents of the axis with the heaviest across the northern RMI. Showers may be heavy at times and the lightning risk will be moderate. This trough will gradually move westwards over the coming days. TUTT... The TUTT enters the region near 25N180 and extends southwest through a TUTT cell near 17N165E (southwest of Wake Island), and continues south to near EQ160E. The TUTT is interacting with a several surface troughs to produce numerous showers and scattered thunderstorms, mainly near the TUTT cell to the southeast and southwest of Wake Island, and then further south over the northern RMI and near Kosrae. Scatterometry data shows a few stronger gusts of around 22 knots (25 mph) over the northern RMI. This feature is expected to remain quasi-stationary over the next few days and maintain unsettled, stormy conditions. OTHER SYSTEMS... ...ITCZ... A fragmented ITCZ enters the region near 4N180 and extends west- northwestward to near 5N160E where it intersects with the aforementioned trade-wind trough. Most of the convection along the ITCZ is seen near the Date Line and along the trough axis over the northern CNMI. The ITCZ looks to persist over eastern Micronesia through the weekend with little change in organization or intensity through early next week. $$ Bowsher