Tropical Cyclone 05W (Doksuri) / Invest 91W
Monday, July 24, 2023

Current Snapshot

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By PDC’s Senior Weather
Specialist Glenn James

The Pacific Disaster Center’s (PDC Global) Monday, July 24, 2023, Tropical Cyclone Activity Report…for the Pacific Ocean, the Indian Ocean, and adjacent Seas

Current Tropical Cyclones:

Super Typhoon 05W (Doksuri)…is located approximately 279 NM northeast of Manila, Philippines


Northeast Pacific Ocean:

There are no tropical cyclones


Central Pacific Ocean:

There are no tropical cyclones


Western Pacific, Indian Ocean and adjacent Seas:

Super Typhoon 05W (Doksuri)

According to the JTWC Warning number 15

Sustained winds were 130 knots…with gusts to near 160 knots

Animated enhanced infrared (eir) satellite imagery indicates the system went through a short weakening cycle, followed by another burst of intensification, with the eye temperature and cloud tops cooling, with the coldest cloud tops completely encircling the 25 NM wide eye. However, over just the last hour, the robust eyewall appears to be weakening slightly on the northwest side as the eyewall convection continues to pulse. A microwave image shows that the stationary banding complex (sbc) which was present in earlier imagery remains firmly entrenched along the southern periphery of the system, and the associated moat of relatively dry air devoid of convection, now extends all the way to the southeastern quadrant. This setup marks the early stages of an eyewall replacement cycle (ewrc).

The system is still tapping into the poleward outflow channel into the cutoff low south of Kyushu, with eastward outflow being enhanced by the development of an upper-level anticyclone to the southeast near 15N 130E. Shear remains very low and sea surface temperatures are warm, providing an overall favorable environment.

The latest global model fields suggest this ridge complex will shift eastward but remain oriented on a general northwest-southeast axis through to a north-south axis through 72 hours before shifting to a more north-south axis thereafter. This will allow for TY 05W to continue tracking northwestward through the majority of the forecast, before turning more northward towards the later portion of the forecast period. the exact orientation of the ridge will have a significant impact on the track of TY 05W, which when combined with the wobbles frequently associated with strong typhoons, introduces uncertainty into the exact track in the first 72 hours of the forecast. The system is expected to skirt the northeast tip of Luzon by 24 hours, then track southwest of Taiwan after 48 hours, making landfall along the eastern coast of China near Xiamen after 72 hours.

From an intensity perspective, the system has likely already reached its peak intensity, or will within the next 6 to 12 hours. While shear, outflow and ocean conditions remain favorable, the primary influence in the near-term intensity forecast will be the onset of the ewrc. As discussed above, the latest microwave imagery indicates the process has already started or will imminently. Once the secondary eyewall formation (sef) process starts in earnest, the intensity will drop quickly, though the duration of the cycle and the amount of weakening is unpredictable.

The current forecast calls for about 15 knots of weakening due to the ewrc, with a slow pace of weakening to 48 hours as the system attempts to recover. The combination of decreasing sea surface temperatures and upper-level outflow and disruption of the low-level flow due to terrain influences passing Taiwan, will result in a more rapid pace of weakening as the system approaches landfall. the system will likely dissipate by 120 hours to the west of Shanghai.

>>> There’s an area of disturbed weather being referred to as Invest 91W…which is located approximately 211 NM east-southeast of Yap.

Animated infrared imagery show an area of flaring and cycling deep convection to the southwest of a broad and slowly consolidating low level circulation center (llcc). Recent  scatterometery revealed a broad circulation relatively weak circulation, with some high winds up to 25-30 knots along the southern flank as part of a westerly wind burst, but otherwise shows winds of 15 knots or less in the other quadrants..

Environmental analysis indicates that current conditions are marginal for intensification with warm sea surface temperatures, and low (05-10 knot) vertical wind shear being offset by moderate northerly flow coming from
the outflow of TY 05W to the northwest.

Global models are in agreement that 91W will continue to meander slowly towards the north-northwest for the next 24 hours before picking up speed towards the northwest after 48 hours, while ensembles are predicting a northeastward track before recurving to the northwest along a similar timeline. Global models suggest the system will slowly consolidate through 48 hours, before gradually intensifying thereafter.

Maximum sustained surface winds are estimated at 10 to 15 knots.

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