Tropical Cyclone Flossie / Tropical Cyclone 04W / Invest 98W – Pacific
Tuesday, July 1, 2025

Current Snapshot

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By PDC’s Senior Weather
Specialist Glenn James

The Pacific Disaster Center’s (PDC Global) Tuesday, July 1, 2025, Tropical Cyclone Activity Report…for the Pacific Ocean, the Indian Ocean, and adjacent Seas

Current Tropical Cyclones:

Tropical Cyclone 06E (Flossie)…is located about 150 miles southwest of Manzanillo, Mexico

Tropical Cyclone 04W…is located about 782 NM southeast of Yokosuka, Japan

 

Northeast Pacific Ocean:  

Tropical Cyclone 06E (Flossie)

FLOSSIE MOVING WEST-NORTHWESTWARD

According to the NHC advisory number 11

Flossie is moving toward the northwest near 7 mph (11 km/h). A west-northwest to northwest motion is anticipated during the next few days. Maximum sustained winds are near 110 mph (175 km/h) with higher gusts. Some additional strengthening is possible today and tonight. By Wednesday, steady to rapid weakening is expected. Hurricane-force winds extend outward up to 25 miles (35 km) from the center and tropical-storm-force winds extend outward up to 90 miles (150 km).

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Warning is in effect for…

* Punta San Telmo to Playa Perula

A Tropical Storm Watch is in effect for…

* East of Punta San Telmo to Zihuatanejo
* North of Playa Perula to Cabo Corrientes

HAZARDS AFFECTING LAND

RAINFALL: Hurricane Flossie should produce additional rainfall totals of 2 to 4 inches, with isolated maximum totals of 6 inches, across coastal portions of the Mexican states of Michoacán, Colima, and Jalisco into Wednesday. This rainfall could lead to localized flash flooding.

WIND: Tropical storm conditions are expected within portions of the warning area, and are possible within the watch areas, for the next several hours.

SURF: Swells generated by Flossie will affect portions of the coast of southwestern Mexico during the next few days. These swells are likely to cause life-threatening surf and rip current conditions.


South of Southwestern Mexico:

>>> An area of low pressure is forecast to develop several hundred miles offshore of southwestern Mexico late this week. Environmental conditions appear conducive for some gradual development of this system thereafter, and a tropical depression could form over the weekend while it moves generally west-northwestward.

* Formation chance through 48 hours…low…near 0 percent
* Formation chance through 7 days…medium…40 percent

 

Central Pacific Ocean: There are no Tropical Cyclones

Tropical cyclone formation is not expected during the next 7-days.

 

Western Pacific, Indian Ocean, and adjacent Seas:  

Western Pacific

Tropical Cyclone 04W

According to the JTWC Warning number 1, sustained winds are 30 knots with gusts to 40 knots

Tropical depression 04w with deep convection slightly offset to the north of a partially exposed low-level circulation center (llcc) and a large band of convection along the eastern periphery of the system. An ascat image revealed the asymmetric nature of the wind field with the strongest winds (25-30 knots)confined to the eastern semicircle.

Environmental analysis indicates that 04W is in a marginally favorable environment characterized by strong poleward outflow aloft, low to moderate (15-20 knots) vertical wind shear, and warm sea surface temperatures. The tropical upper tropospheric trough (tutt) cell that is centered about 300 NM to the southwest of the system is currently hindering the equatorward outflow and is the main cause of the southerly vertical wind shear. The tutt cell is also introducing a tongue of dry air to the southern and southwestern portions of the circulation.

TD 04W is forecast to continue on a north-northwesterly track along the western periphery of the str through 48 hours. After 48 hours, ridging to the west will build and pull the vortex toward the northeast through the remainder of the forecast period.

Regarding intensity, 04W is forecast to steadily intensify to a peak intensity of 55 knots at 72 hours due to the overall conducive environment. The system will continue to distance itself from the tutt cell, which will allow for improvements to the equatorward outflow channel as the system gains latitude.

After 72 hours, sea surface temperatures will begin to cool, putting a halt to further intensification. And by 120 hours, sea temperatures are expected to drop, which will initiate a weakening trend. Additionally, an upper-level trough is forecast to propagate eastward and begin interacting with the system near 120 hours.

>>> An area of disturbed weather, which is being referred to as Invest 98W, is located approximately 240 NM northeast of Legazpi, Philippines

Multi-spectral satellite imagery (msi) depicts a slowly consolidating low level circulation center (llcc) with isolated convection throughout the circulation. An ascat-c pass shows turning in the northern periphery, continuing to show a more defined circulation.

Environmental analysis reveals a highly favorable environment for development with low level vertical wind shear (vws) of 10-15 knots, good upper-level outflow and warm sea surface temperatures (sst).

Deterministic and ensemble models are in good agreement for development with a low likelihood of development over the next 48 hours.

Maximum sustained surface winds are estimated at 13 to 25 knots.

The potential for the development of a significant tropical cyclone within the next 24 hours remains low.