Current Snapshot

The Pacific Disaster Center’s (PDC Global) Thursday, September 5, 2024, Tropical Cyclone Activity Report…for the Pacific Ocean, the Indian Ocean, and adjacent Seas

Current Tropical Cyclones:

Tropical Cyclone 12W (Yagi)…is located approximately 371 NM east-southeast of Hanoi, Vietnam

Tropical Cyclone 13W (Leepi)…is located approximately 421 NM east of Yokosuka, Japan

Northeast Pacific Ocean: There are no Tropical Cyclones

>>> Offshore of Southwestern Mexico:

An area of low pressure is forecast to form early next week off the coast of southern Mexico. Environmental conditions could support gradual development of this system thereafter while it moves generally west-northwestward, roughly parallel to the coast of southwestern Mexico.

* Formation chance through 48 hours…low…near 0 percent
* Formation chance through 7 days…low…30 percent

Central Pacific Ocean: There are no Tropical Cyclones…nor any areas of disturbed weather under investigation by the Central Pacific Hurricane Center (CPHC)

Western Pacific, Indian Ocean, and adjacent Seas:

Super Typhoon 12W (Yagi)

According to the JTWC Warning number 19, sustained winds are 130 knots with gusts to near 160 knots

Typhoon 12W has weakened slightly while undergoing an eyewall replacement cycle (erc). Animated enhanced infrared (eir) satellite imagery depicts a 20 NM round eye, which supports the initial position with high confidence. Eir imagery does indicate a strengthening eyewall with cooling cloud top temperatures, which could lead to a slight intensification over the next six hours or so. A microwave image shows that the small inner eyewall has remained intact, with the outer eyewall weakening over the southwest quadrant.

Environmental conditions remain favorable with radial outflow and low vertical wind shear thus, the current weakening trend is solely attributed to the erc. While environmental conditions remain favorable over the next 06-12 hours, some re-intensification is possible after the erc completes. After 12 hours, the system will track westward approaching Hainan Island, with a more pronounced weakening trend due to interaction with land.

After 24 hours, rapid weakening will occur as the system tracks over southern China and northern Vietnam, with landfall expected near 48 hours. As the system tracks into the rugged terrain of northern Vietnam, it will dissipate by 72 hours.

Tropical Cyclone 13W (Leepi)

According to the JTWC Warning number 9, sustained winds are 30 knots with gusts to near 40 knots

Animated multi-spectral satellite imagery (msi) depicts a small cluster of flaring convection sheared to the south of the low level circulation center (llcc), which accounts for the recent full-exposure of the llcc. Vigorous equatorward outflow with transverse banding around the eastern and southern peripheries aided in the system reaching a peak intensity of 35 knots; however, the intensity weakened to 30 knots once the system decoupled. TD 13W is located underneath a tutt cell and immediately adjacent to an extensive area of dry air and subsidence to the west of its current position and forecast track.

TD 13W has a few advantages in the short term, including the vigorous equatorward outflow mentioned above, a well-wrapped low level cloud system, and warm sea surface temperatures throughout the forecast period. Although the intensity weakened slightly (by 5 knots) after the system became decoupled, the marginally favorable environmental conditions will allow the intensity to fluctuate upwards to 35 knots again near 12 hours.

However, the position in relation to the tutt cell overhead is problematic due to a weak convergent influence aloft, which will inhibit further development. TD 13W has a strong steering influence which will recurve it around the ridge axis and cause it to accelerate northeastward as it nears the mid-latitude westerlies. The environment will become increasingly hostile with unfavorable vertical wind shear (30-34 knots) by 24 hours and beyond. By 36 hours, the system will venture into mid-latitude territories where a strong shared energy jet max exists poleward. A baroclinic influence in the higher latitudes will lead to the extra-tropical transition of TD 13W by 48 hours.

>>> There’s an area of disturbed weather, being referred to as Invest 95W, which is located approximately 208 NM east-northeast of Kosrae.

Enhanced infrared imagery and a microwave image depicts a broad area of turning obscured by flaring convection to the southwest.

Environmental analysis indicates 95W is in a favorable environment for development with low to moderate (10-15 knot) vertical wind shear, good poleward outflow aloft, and warm sea surface temperatures.

Global models are in good agreement that 95W will continue to track west-northwestward and continue to intensify over the next 48 hours.

Maximum sustained surface winds are estimated at 13 to 18 knots.

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