The Western Pacific has become a bustling hub of tropical activity, with multiple systems churning across the region—each posing unique hazards from strong winds to flooding rains. While the official peak of the typhoon season typically arrives later in August and September, current conditions would suggest otherwise.
A newly-formed tropical storm, located due south of Tokyo, is already being tracked closely by meteorologists. The Joint Typhoon Warning Center (JTWC) has upgraded the system to tropical storm status, although the Japan Meteorological Agency (JMA) has yet to name it, often taking a more conservative approach. Satellite imagery reveals a lopsided structure, typical of developing systems, with the strongest winds displaced to the east of the storm’s center.
Impacts to Japan
Forecast models suggest the center of this tropical storm will pass near or just southeast of Tokyo. While the city may be spared direct tropical storm-force winds if the storm maintains its current path, even a slight westward jog could bring gusty winds and heavy rain to major population centers including Chiba, Kanagawa, and even U.S. military facilities in areas like Yokosuka and Zushi.
Rainfall remains a major concern. Even if the storm does not make direct landfall, it will drag in a significant plume of tropical moisture. Widespread showers and embedded thunderstorms are expected across eastern and northeastern Japan, including the Tohoku region. These rains will arrive in pulses, increasing the risk of flooding and landslides—especially in mountainous and volcanic terrain along the Kii Peninsula, the Izu Islands, and parts of Shikoku.
Second System Across Southwestern Japan and Korea
Simultaneously, a separate area of low pressure is organizing over the southern Japanese islands, including Okinawa. This tropical depression is contributing to messy weather, with gusty winds and locally heavy downpours. As it drifts toward the Korean Peninsula, it is expected to interact with the broader monsoon flow, amplifying rainfall across southwestern Japan and potentially fueling a conveyor belt of moisture through Tuesday and Wednesday.
This atmospheric “river” will tap into the warm, moist air over the Pacific, delivering rounds of rain across central and southern Japan. Flash flooding, urban ponding, and landslides are all possible hazards in the coming days.
Remnants Still Lingering
Meanwhile, the remnants of Severe Tropical Storm Danas—known locally in the Philippines as Bising—continue to impact southeastern China. Guangdong province has been particularly hard-hit, with ongoing rainfall still contributing to flood risks nearly two weeks after the storm’s initial formation.
The long-lasting system previously affected Taiwan, where it produced record-breaking winds and heavy rain. Despite its classification now being downgraded, the storm’s moisture-laden remnants remain active and are adding to the broader meteorological complexity in the region.
Watching the Philippine Sea: 94W and Beyond
Looking farther south and west, meteorologists are paying close attention to Invest 94W, a broad area of low pressure currently over the Philippine Sea. Long-range guidance, including ensemble models from the ECMWF and GFS, shows a high probability for tropical cyclone development between July 17 and 20.
While operational models are not yet in perfect agreement, both the European and American runs show a sizable low-pressure system forming and potentially tracking west-northwest. More importantly, this system is expected to enhance the southwest monsoon—or Habagat—across the Philippines. This “monsoonal gyre” pattern, although not a formal meteorological term, aptly describes the sprawling nature of the developing system, which could spin up a wide shield of rain impacting multiple countries.
Regardless of whether a named storm emerges, the enhanced monsoonal flow will increase rainfall across the central and northern Philippines. Initial impacts are expected across the Visayas around Tuesday or Wednesday of next week, before precipitation gradually shifts toward Luzon.
This setup is known to create persistent “training” thunderstorms—lines of storms that repeatedly pass over the same areas. In these situations, rainfall totals can quickly climb, triggering flash floods and mudslides, especially in mountainous areas and along riverbanks.
An Interconnected Web of Systems
Adding to the challenge is the sheer number of active systems in the basin. Each tropical entity—from Japan to China to the Philippines—acts as a cog in a larger meteorological machine. These storms don’t simply form and move in isolation; they influence one another through shifts in pressure, steering flow, and moisture distribution.
The current state of the Western Pacific resembles a chaotic pool table—systems bouncing off one another and redistributing energy across the region. There is no indication that these storms will consolidate into a single large typhoon, but their cumulative effects are already being felt.
Model Consensus Builds
Model ensembles—those “spaghetti plots” familiar to anyone tracking tropical cyclones—are in broad agreement that something will take shape in the Philippine Sea. The tight clustering of circles from the ECMWF ensemble around July 17 to 20 suggests growing confidence in development.
Both the GFS and ECMWF operational runs show a large, loosely organized storm forming during this window. While there is still variability in exact track and intensity, the implications for increased rainfall across the Philippines—and possibly Taiwan or southern China later—are increasingly likely.
A Busy Start to Typhoon Season
Although it’s still early July, the Western Pacific is behaving as though the heart of typhoon season has already arrived. With multiple systems simultaneously active or developing, it’s a reminder that vigilance is necessary even before the traditional peak.
For residents of Japan, China, Korea, and the Philippines, this week brings a mix of storm hazards: tropical wind gusts, torrential rains, and flooding. As new systems continue to emerge, staying informed and prepared is key.
As always, meteorological monitoring continues around the clock. Further updates will be issued as forecasts evolve and impacts become clearer. For now, eyes remain fixed on the Philippine Sea and the broader Western Pacific as this complex weather pattern continues to unfold.
Robert Speta is a meteorologist specializing in Western Pacific tropical weather. He provides ongoing coverage through video briefings and detailed analysis. To support his continued work, you can join his Patreon community.