Current Snapshot

The Pacific Disaster Center’s (PDC Global) Friday, August 11, 2023, Tropical Cyclone Activity Report…for the Pacific Ocean, the Indian Ocean, and adjacent Seas

Current Tropical Cyclones:

Tropical Cyclone 05E (Dora)…is located about 609 miles west of Johnston Island

Tropical Cyclone 07W (Lan)…is located approximately 422 NM south-southeast of Yokosuka, Japan

Northeast Pacific Ocean:

Central East Pacific…

Invest 98E

Satellite data indicate that the circulation associated with an area of low pressure located several hundred miles southwest of Manzanillo, Mexico, is gradually becoming better defined. However, the associated shower and thunderstorm activity remains disorganized. Environmental conditions are conducive for gradual development of this system, and a tropical depression is likely to form late this weekend or early next week while it moves westward or northwestward at about 10 mph across the central portion of the basin.

* Formation chance through 48 hours…medium…50 percent
* Formation chance through 7 days…high…80 percent

Western East Pacific…

A broad area of low pressure associated with a tropical wave is producing a large area of disorganized showers and thunderstorms well to the east-southeast of the Hawaiian Islands. Conditions appear conducive for development of this system, and a tropical depression could form during the next few days while moving toward the west or west-northwest at about 10 mph across the far western portion of the basin, crossing into the Central Pacific basin on Sunday.

* Formation chance through 48 hours…medium…40 percent
* Formation chance through 7 days…medium…60 percent

Off the coast of southern Mexico…

An area of low pressure is forecast to form offshore of Central America and the southern coast of Mexico in a couple of days. Environmental conditions are expected to be conducive for development of this system, and a tropical depression is likely to form during the early or middle part of next week while it moves generally west-northwestward, roughly parallel to the coast of southern and southwestern Mexico.

* Formation chance through 48 hours…low…near 0 percent
* Formation chance through 7 days…high…70 percent

Central Pacific Ocean:

>>> Far east-southeast of the main Hawaiian Islands:

A broad area of low pressure associated with a tropical wave is producing a large area of disorganized showers and thunderstorms well to the east-southeast of the Hawaiian Islands. Conditions appear conducive for development of this system, and a tropical depression could form during the next few days while moving toward the west or west-northwest at about 10 mph across the far western portion of the basin, crossing into the Central Pacific basin on Sunday.

* Formation chance through 48 hours…medium…40 percent
* Formation chance through 7 days…medium…60 percent

>>> Central East Pacific…

Invest 98E

An area of low pressure located about 3000 miles east-southeast of Hilo, Hawaii, is gradually becoming better defined. However, the associated shower and thunderstorm activity remains disorganized. Environmental conditions are conducive for gradual development of this system, and a tropical depression is likely to form late this weekend or early next week while it moves westward or northwestward at about 10 mph across the central portion of the basin.

* Formation chance through 48 hours…medium…50 percent.
* Formation chance through 7 days…high…80 percent.

Western Pacific, Indian Ocean and adjacent Seas:

Western Pacific…

Tropical Cyclone 05E (Dora)

According to the JTWC warning number 47…

Dora the explorer has discovered her third basin, crossing from the central Pacific into the western Pacific, and is now known as Typhoon 05E. Animated multi-spectral satellite imagery depicts a vanishing eye over the past 12 hours as cloud tops have cooled in the center of the storm. Dora’s inner core remains remarkably compact, showing a radius of maximum winds of only 6 NM.

Upper-level outflow is primarily poleward into the southeastern flank of an upper-level trough to the northwest. some mid-level southwesterly shear of about 20 knot magnitude is now impacting the storm, and the central dense overcast has accordingly become asymmetric.

Typhoon 05E (Dora) continues to progress through its decay phase, as the compact inner core is vulnerable to even moderate shear, and southwesterly mid-level shear is now disrupting the core structure. this shear may increase slightly over the next 24-48 hours as Dora rounds the western flank of the subtropical ridge and moves northwestward toward an upper-level trough. This trough is expected to pinch off into a cut-off low, preventing shear from becoming strong enough to kill Dora quickly.

Rather steady weakening is expected during the forecast period as shear and dry air progressively erode Dora’s structure. Some models suggest an opportunity for Dora to restrengthen briefly in 4-5 days if the upper low backs away enough to lower shear values for a time, but this will depend on how much of Dora is left at that moment. For now, the JTWC forecast shows decay to a 30 knot tropical depression by 120 hours.

Tropical Cyclone 07W (Lan)

According to the JTWC Warning number 18…

Sustained winds were 85 knots…with gusts to near 105 knots

Animated enhanced infrared satellite imagery depicts warming convective cloud tops surrounding a still well-defined 29 NM diameter eye, reflecting the first stage of a weakening trend. A previously robust poleward outflow channel has continued to wane as the driving mechanism, an upper-level low to the north, moves away from the system.

TY 07W will continue its turn toward the northwest over the next six hours as subtropical ridging builds to the north and east, uninhibited by features associated with the mid-latitude baroclinic zone well to the north. The system will follow the flow associated with the current steering ridge throughout the forecast period, first northwestward through 36 hours and increasingly poleward thereafter. A deep-layer trough will dig equatorward to the northwest of the system in the extended period, setting a limit to the western extent of the steering ridge and the dependent storm track.

TY 07W is still expected to make landfall at typhoon intensity southeast of Kyoto and Osaka just after 72 hours, although declining ocean heat content, contention with drier air upstream, and reduced divergence aloft will continue to slowly weaken the system.

In the extended range passage over land and interaction with a developing trough to the northwest will accelerate the weakening trend and induce the beginning of extratropical transition.