🌪️ WESTERN PACIFIC Tropical Weather Update: New Cyclone Threat Developing Near Guam as In-Fa Moves Away

Friday, November 6, 2026 | Western North Pacific

By Paul Harrison | Founder & Publisher, Orbis Weather

GUAM / WESTERN PACIFIC — A new tropical disturbance east-northeast of Guam has become the main focus of tropical cyclone monitoring across the Western North Pacific, with forecasters identifying favorable conditions for further development during the next 24 to 48 hours.

The Joint Typhoon Warning Center (JTWC) has classified Invest 99W as having a HIGH potential for significant tropical cyclone development within 24 hours, raising concerns about strengthening winds, heavy rainfall and deteriorating marine conditions around the Mariana Islands.

Meanwhile, Tropical Storm In-Fa (30W), previously a typhoon, has accelerated northeastward into the open Pacific east of Japan. JTWC has issued its final tropical cyclone warning on the system.

Although the Western Pacific currently has no active tropical cyclones listed in JTWC’s November 6 basin-wide summary, the developing disturbance near Guam warrants close attention.

This Orbis Weather report examines the latest tropical activity, development potential, regional threats, forecast uncertainty and conditions to monitor over the coming days.

🌀 1. Western Pacific Tropical Activity — Latest Status

JTWC ADVISORY | NOVEMBER 6, 2026, 06:00 UTC (2:00 PM GUAM TIME)

Important: A high development potential is not the same as a confirmed tropical storm or typhoon. The disturbance must develop a sufficiently organized circulation and meet operational classification criteria before receiving a tropical cyclone designation.

🌧️ 2. Invest 99W — Tropical Cyclone Formation Threat Near Guam

The most significant tropical weather development today involves Invest 99W, a consolidating disturbance over the western Pacific Ocean.

According to JTWC’s November 6 advisory, satellite observations show an increasingly organized low-level circulation accompanied by developing deep thunderstorms.

Latest analyzed information

The disturbance is moving through an environment containing warm ocean water and generally supportive upper-atmospheric conditions.

Satellite and scatterometer observations indicate that winds are beginning to wrap more completely around the developing circulation, suggesting that the system is becoming better organized.

JTWC reports that numerical weather prediction models generally support continued consolidation as the disturbance approaches and passes the Mariana Islands region.

However, the precise track, timing of development and eventual intensity remain uncertain.

🌡️ 3. Why Conditions Favor Tropical Development

Several atmospheric and oceanic factors are influencing Invest 99W.

Warm ocean temperatures: Sea surface temperatures near 28–29°C provide sufficient oceanic heat to support tropical convection and potentially intensifying thunderstorms.

Vertical wind shear: JTWC identifies low-to-moderate wind shear in the surrounding environment. Stronger shear can disrupt cyclone organization, while weaker shear generally allows thunderstorms to remain closer to the circulation center.

Upper-level outflow: Ventilation in the upper atmosphere can help remove air rising through deep thunderstorms, supporting the development of a more organized tropical system.

Improving circulation: Recent satellite observations suggest that the low-level circulation is consolidating, although its structure remains under development.

These factors support an elevated development risk, but they do not guarantee that the disturbance will become a named tropical storm or typhoon.

🧭 4. Where Is Invest 99W Heading?

JTWC guidance indicates that Invest 99W should generally move west-northwestward over the next 24 hours, approaching the vicinity of the Mariana Islands.

The system could strengthen while moving across the western Pacific, but substantial differences can develop between model projections, particularly when a disturbance has not yet established a well-defined center.

Forecast monitoring timeline

This timeline describes monitoring priorities, not confirmed forecast positions or intensities.

Residents and maritime operators should avoid interpreting a projected track as an exact prediction. Even a disturbance that passes offshore can generate heavy showers, gusty winds and dangerous seas.

⚠️ 5. Latest Development — Invest 99W Upgraded to Tropical Depression 31W

Important November 6 update: A later National Weather Service Guam bulletin confirms that JTWC has upgraded Invest 99W to Tropical Depression 31W.

The bulletin, issued at 7:09 p.m. Chamorro Standard Time on November 6, reports:

• Maximum sustained winds: 30 mph (48 km/h).

• Movement: Northwest at 21 mph (34 km/h).

• Expected track: Passing north of Agrihan early Saturday.

• Intensity outlook: Potential strengthening into a weak tropical storm.

• Main concern: Heavy showers, gusty winds and deteriorating local conditions.

The National Weather Service indicates that tropical-storm-force winds are expected to remain north of the center, with damaging winds not currently anticipated for Alamagan, Pagan or Agrihan. Residents should nevertheless follow subsequent warnings because the forecast could change.

🇬🇺 6. Guam and Northern Mariana Islands — Regional Impacts

The Northern Mariana Islands are the primary area of concern as Tropical Depression 31W approaches.

The National Weather Service has highlighted the possibility of increasing showers, thunderstorms and gusty winds, especially across the northern islands.

An earlier November 6 special weather statement indicated that rainfall totals of approximately 1–2 inches (25–51 mm) and wind gusts reaching 40 mph (64 km/h) were possible near the northern islands.

The most important locations to monitor include Alamagan, Pagan and Agrihan.

For Guam, Saipan and Tinian, conditions may vary considerably depending on the cyclone’s track and the distribution of rainbands.

Residents should monitor official forecasts for any changes in wind, rainfall, coastal and marine hazards.

🇯🇵 7. Tropical Storm In-Fa — Final Warning Issued

Tropical Storm In-Fa, designated 30W by JTWC, is no longer listed as an active tropical cyclone in the agency’s November 6 basin-wide summary.

The system previously strengthened into a typhoon before encountering increasingly unfavorable atmospheric conditions as it moved northeastward east of Japan.

Latest available storm analysis

These figures refer to the latest available observations, not a new live tropical cyclone position.

In-Fa has moved into the midlatitude Pacific environment, where interaction with frontal systems and strong upper-level winds can change the character of a storm.

Although tropical cyclone warnings have ended, a transitioning or extratropical system can still produce dangerous winds and waves over open water.

Mariners should continue consulting marine forecasts rather than assuming that the final tropical cyclone warning means all hazards have ended.

🇵🇭 8. Philippines — Tropical Weather Outlook

The Philippines remains an important monitoring area during November, particularly for tropical systems developing east of the archipelago.

Tropical Depression 31W is currently focused much farther northeast, near the Mariana Islands, rather than immediately approaching the Philippine coastline.

However, its longer-range movement and intensity remain important to monitor.

Weather systems that develop over the Philippine Sea can follow substantially different tracks depending on the strength and position of subtropical high pressure and surrounding steering currents.

Residents of Luzon, the eastern Visayas and other Pacific-facing coastal areas should continue checking PAGASA advisories for any new tropical cyclone information.

No specific Philippine tropical cyclone wind signal or landfall threat has been independently confirmed for this report.

🇹🇼 9. Taiwan, Southern Japan and East China Sea

There is no verified immediate landfall forecast for Tropical Depression 31W affecting Taiwan or the Japanese mainland in the advisories reviewed for this report.

Nevertheless, longer-range model guidance should be monitored as the system develops.

The main factors influencing future movement include:

• The position of the western Pacific subtropical ridge.

• Changes in upper-level steering winds.

• Interaction with approaching midlatitude weather systems.

• The cyclone’s eventual intensity and circulation depth.

Any significant change in these atmospheric features could alter the forecast track.

Forecast uncertainty generally increases with time, so five-day model projections should not be interpreted as confirmed future storm positions.

🌊 10. Western Pacific Marine Conditions

Tropical cyclones and developing disturbances can generate hazardous seas well beyond their immediate centers.

The primary marine concerns associated with Tropical Depression 31W include increasing winds near the developing circulation, rough seas and reduced visibility in heavy thunderstorms.

The National Weather Service Guam has also highlighted elevated surf and rip-current concerns along exposed reefs in the Mariana Islands.

Mariners, fishing vessels and recreational boaters should monitor marine forecasts, especially when operating near the Northern Mariana Islands.

Marine safety guidance: Avoid navigating through strong thunderstorms, monitor updated wind and wave forecasts, and follow local port authority instructions.

🌏 11. El Niño and the Western Pacific Tropical Environment

The broader tropical Pacific climate is also being influenced by an exceptionally strong El Niño event.

In its October 9, 2026 outlook, the Japan Meteorological Agency reported that El Niño conditions had strengthened considerably during 2026.

The agency identified a September sea surface temperature anomaly of +4.0°C in the Niño 3 region, exceeding the previous record in its dataset.

JMA expects the event to persist into the Northern Hemisphere winter.

El Niño can influence tropical cyclone activity by altering atmospheric circulation, wind shear, convection and the location of tropical cyclone formation.

However, the relationship between El Niño and individual typhoons is complex.

A strong El Niño does not mean every disturbance will intensify rapidly, nor does it guarantee that a particular location will experience a typhoon.

Individual storm development still depends on short-term atmospheric and oceanic conditions.

📅 12. Western Pacific Tropical Outlook — Next Five Days

NOVEMBER 6–11, 2026

JMA-based guidance reported on November 6 indicates that the system could reach typhoon strength around November 10. This is a forecast scenario, not a confirmed outcome.

🔎 13. What Orbis Weather Is Monitoring

The most important developments over the next 24–72 hours are the strengthening and movement of Tropical Depression 31W, its proximity to the Northern Mariana Islands, and whether the cyclone develops into a named tropical storm.

Additional priorities include changes in rainfall and wind forecasts for the islands, dangerous marine conditions, and any new tropical disturbances elsewhere across the basin.

Orbis Weather will continue monitoring official tropical cyclone information from regional meteorological agencies.

🛡️ 14. Tropical Cyclone Preparedness

People living in cyclone-prone areas of the Western Pacific should maintain basic emergency preparations throughout the tropical cyclone season.

Useful precautions include keeping drinking water and essential medication available, charging mobile devices and backup power supplies, securing loose outdoor objects, and knowing where to obtain official evacuation information.

During heavy rainfall, avoid driving or walking through flooded roads. Coastal residents should also remain alert for dangerous surf and strong rip currents.

For Guam and the Northern Mariana Islands, official National Weather Service Guam bulletins should take priority over general regional weather summaries.

📚 15. Official Weather Sources and Forecast Verification

Orbis Weather uses publicly available meteorological information to explain tropical weather developments and potential hazards.

The following agencies provide the primary operational information relevant to this report.

Editorial methodology

This report is independently written for Orbis Weather using official meteorological advisories, satellite-based assessments and published forecast guidance.

Storm positions, wind estimates and classifications can differ between agencies because of observation times, wind-averaging methods and operational classification criteria.

Forecast tracks and intensities are subject to revision as new observations become available.

The analysis distinguishes observed conditions from forecast scenarios and does not treat model guidance as a confirmed outcome.

Reporting cutoff: This article incorporates November 6, 2026 advisories, including the evening Guam-time upgrade to Tropical Depression 31W. Conditions may change after publication.

🌪️ 16. Final Outlook

The Western Pacific’s tropical weather focus has shifted from the departing In-Fa to a newly developing cyclone near the Northern Mariana Islands.

Tropical Depression 31W is now the principal system to watch, with further strengthening possible as it moves northwestward.

The immediate priority is monitoring conditions across the northern CNMI, where heavy showers, thunderstorms and gusty winds may accompany the developing system.

Further west, the longer-range track remains uncertain, and it is too early to establish a reliable landfall threat for the Philippines, Taiwan or Japan.

Orbis Weather will continue following official advisories as the situation evolves.