Current Snapshot

The Pacific Disaster Center’s (PDC Global) Thursday, September 26, 2024, Tropical Cyclone Activity Report…for the Pacific Ocean, the Indian Ocean, and adjacent Seas

Current Tropical Cyclones:

Tropical Cyclone John, is located about 65 miles west of Lazaro Cardenas, Mexico

Tropical Cyclone 18W (Cimaron), is located about 297 NM south-southeast of Sasebo, Japan – Final Warning

Tropical Cyclone 19W, is located about 457 NM south-southeast of Iwo To, Japan

Northeast Pacific Ocean:

Tropical Cyclone John

CENTER OF JOHN JUST OFFSHORE THE COAST OF THE MEXICAN STATE OF MICHOACAN…CATASTROPHIC FLASH FLOODING AND MUDSLIDES ONGOING OVER PORTIONS OF SOUTHERN AND SOUTHWESTERN MEXICO

According to the NHC advisory number 17

John is moving toward the northwest near 5 mph (7 km/h) and this motion is expected to continue through early Friday morning. On the forecast track, the center of John is forecast to approach and move along the coast of southwestern Mexico or just inland later tonight or early Friday.

Maximum sustained winds are near 70 mph (110 km/h) with higher gusts. Gradual weakening is expected tonight, with faster weakening forecast on Friday while the center interacts more with the topography of Mexico.

Tropical-storm-force winds extend outward up to 160 miles (260 km) from the center.

HAZARDS AFFECTING LAND

RAINFALL: Through Friday, Hurricane John is expected to produce additional rainfall amounts of 10 to 20 inches across portions of the Mexican States of Guerrero and Michoacán. Additional rainfall of 2 to 4 inches with locally up to 6 inches expected across the Mexican States of Colima and western Oaxaca.

STORM SURGE: A dangerous storm surge is expected to produce coastal flooding near and to the east of where the center makes landfall. Near the coast, the surge will be accompanied by large and destructive waves.

WIND: Hurricane conditions are expected along the coast within the
hurricane warning area by tonight or early Friday. Winds are expected to first reach tropical storm strength later within a few hours. Wind speeds atop and on the windward sides of hills and mountains are often up to 30 percent stronger than the near-surface winds indicated in this advisory, and in some elevated locations could be even greater.

Tropical storm conditions are currently occurring over portions of the coast within the tropical storm warning area, and should continue through today.

SURF: Swells associated with John are forecast to continue to affect the coast of southern and southwestern Mexico through the week, with the potential for dangerous surf and rip currents.

Central Pacific Ocean: There are no Tropical Cyclones.

Western Pacific, Indian Ocean, and adjacent Seas:

Tropical Cyclone 18W (Cimaron) – Final Warning

According to the JTWC warning number 10, sustained winds were 25 knots, with gusts to 35 knots.

Animated multi-spectral satellite imagery (msi) depicts a fully exposed low level circulation center (llcc), with persistent flaring convection along convergent low-level flow lines to the northeast. Animated water vapor imagery and high-resolution model fields show a significant amount dry of mid-level air over and west of the llcc, and the latest cimss upper-level analysis reveals an area of convergent flow aloft pushing southward over top of the system from the north.

The environment is unfavorable, with moderate poleward outflow and warm sea surface temperatures offset by moderate to high (20-25 knot) vertical wind shear, and copious amounts of dry mid-level air. The system has tracked westward over the past six hours, meandering in a weak steering pattern.

TD 18W is meandering within the weak steering pattern, having taken a bit of an unexpected jog to the west over the past six hours. The system is likely to make it a little further west in the next few hours, before it starts moving north then northeast as it starts to ride up the enhanced gradient along the frontal boundary to the northeast. Due to the copious dry air and convergent flow aloft, there is little to no chance for convective activity to reform over the center of TD 18W.

What convection has been able to develop over the last 12 hours has been along convergent flow lines and is immediately sheared to the
northeast away from the center. After 12 hours, shear is expected to
increase even more as the system begins to interact with the southern edge of a jet stream max over Japan, which will lead to the rapid dissipation of TD 18W by 24 hours.

As with the previous forecast, it bears mentioning that the GFS model continues to show the vorticity associated with the remnants of TD 18W moving northeastward along the frontal boundary until about 60 hours or so. At this point the GFS shows redevelopment along the leading edge of a northeast surge along the coast of Japan, bringing the remnants of
TD 18W back to life as they slide southwestward in a binary interaction with what is now TD 19W. The system will be closely monitored for signs of this scenario playing out.

Tropical Cyclone 19W

According to the JTWC warning number 3, sustained winds were 35 knots, with gusts to 45 knots.

Animated enhanced infrared (eir) satellite imagery depicts a broad circulation with persistent deep convection forming a central dense
overcast (cdo) feature. Another pass revealed the low level circulation center (llcc) is displaced to the northwestern edge of the cdo feature, and remains mostly obscured in visible imagery.

The accompanying microwave image depicts the broad nature of the circulation well, and shows that the northern hemisphere of the rotation is devoid of significant convection, while the deep convection is oriented in a near-linear band along a northwest to southeast axis. Earlier scatterometer data showed a highly asymmetric wind field, with 25-30 knot winds in a band extending from southeast to north of the llcc, with a radius of maximum winds contracting to about 50 NM.

Analysis reveals a marginal environment. while there appears to be a small point source directly above the system, there is obviously a relatively strong northerly shear component effecting the system. Otherwise, the presence of transverse banding in the eir and water vapor imagery confirms radial outflow directly above the system. Sea surface temperature are very warm but there is a bit of dry air lurking to the west. Lastly there is a well-defined tutt-cell about 600 NM to the northeast and this will have a major effect on TD 19W in the future.

The primary steering mechanism for TD 19W for the full forecast period will be the ridge situated to the northeast. TD 19W will begin rounding the ridge axis by 72 hours, and thereafter begin to rapidly accelerate as the gradient tightens between the ridge to the east and a very strong upper-level trough which moves over Japan. By 96 hours, TD 19W will be moving at nearly 20 knots to the northeast and continuing to accelerate. By the end of the forecast period the system is expected to be east of northern Honshu and moving quickly into the open waters of the northwest Pacific.

In terms of intensity, the main drivers will be dry mid-level air, shear and the tutt-cell. Firstly, the dry air that is currently lurking to the west of TD 19W is expected to remain firmly in place for the first 48 to 60 hours of the forecast. Secondly, deep-layer shear, while currently low, is forecast to pick up to moderate to high levels for roughly the same time period. Lastly, the tutt-cell to the northeast is forecast to move westward while TD 19W moves northwestward, such that the two come almost in alignment by 48 hours. This will place TD 19W to the southwest and south of the tutt-cell, in an unfavorable position with convergent flow aloft.

The combination of factors means that while there may be a very short window of opportunity for a slight amount of intensification in the near-term, that will be it for a while. The forecast calls for steady intensity through 48 hours, but it is possible that the system could weaken slightly during the first 48 hours of the forecast. However, by 72 hours things start to look up. The atmosphere is expected to moisten up, shear drops off considerably, and most importantly the tutt-cell slides west of the system, into a favorable position.

By 72 hours, outflow builds into the base of the approaching trough, allowing for the system to intensify up to a peak of 55 knots by 96 hours. The main limiting factor in the potential intensity will be the relatively large and asymmetric wind field, which will hinder rapid intensification, in an otherwise favorable environment. By 120 hours, the system will be in the throws of extra-tropical transition (ett).

>>> There’s an area of disturbed weather, being referred to as Invest 97W, which is located approximately 278 NM south-southeast of Ishigakijima, Japan

Animated multi-spectral satellite imagery (msi) depicts a more defined and consolidating low level circulation center (llcc), with convective banding wrapping into the center.

Environmental analysis indicates 97W is in a favorable environment for development due to low (5-10 knot) vertical wind shear, good equatorward outflow aloft, and warm sea surface temperatures.

Numerical model guidance is in agreement that 97W will continue to traverse southward, northeast of Luzon, and deepen over the next 24 hours.

Maximum sustained surface winds are estimated at 15 to 20 knots.

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