By PDC’s Senior Weather
Specialist Glenn James
Tropical Cyclone 26W (Nalgae)…is located approximately 220 NM south-southeast of Hong Kong
Tropical Cyclone 27W (Banyan)…is located approximately 108 NM north of Sonsorol – Final Warning
Northeast Pacific Ocean:
There are no tropical cyclones nor any areas of disturbed weather under investigation by the NHC
There are no tropical cyclones nor any areas of disturbed weather under investigation by the CPHC
Northwest and Southwest Pacific Ocean, Indian Ocean, Arabian Sea:
Northwest Pacific Ocean
Tropical Cyclone 26W (Nalgae)
According to the JTWC Warning number 21, sustained winds were 70 knots with gusts to near 85 knots.
Animated multi-spectral satellite imagery depicts a large cluster of persistent deep convection over the western and southern semicircle of a broad low-level circulation center (llcc). Animated enhanced infrared satellite imagery indicates intense convective bursts, and vortical hot towers, now beginning to fully wrap upshear around the outer periphery of the llcc, indicating the system is strengthening.
Environmental conditions are generally favorable, characterized by low (10-15 knots), warm sea surface temperatures and moderate radial outflow and a developing favorable poleward outflow channel.
Tropical storm 26W will continue to track northward over the next 48 hours along the western side of the steering ridge to the east, which is oriented almost due north-south. Additionally, the system is expected to intensify, as an upper-level point source aloft is anticipated to develop aloft along with increased poleward outflow.
These improved environmental factors will allow for steady intensification to a peak of 75 knots by 24 hours. However, after 36 hours, the system will be impacted by cooling sea surface temperatures, dry air entrainment, and reduced outflow which will lead to a steady weakening trend through 120 hours.
Furthermore, the steering pattern evolves, as the ridge to the east builds westward, along with lower-level flow out of the north-northeast. These steering factors will gradually turn TS 26W to the west and then southwest. The system is expected to dissipate over Hainan Island by 120 hours.
Tropical Cyclone 27W (Banyan) – Final Warning
According to the JTWC Warning number 5A, sustained winds were 25 knots with gusts to near 35 knots.
Over the past six hours animated enhanced infrared satellite imagery indicates that tropical storm 27W (Banyan) has continued to hold together surprisingly well, as the system has retained a small central dense overcast of deep convection obscuring the low level circulation center.
The overall environment is marginal, with warm sea surface temperatures and strong equatorward outflow being offset by strong northeasterly flow aloft around the system. However, in the midst of strong and persistent northeasterly flow aloft, the convective burst has enabled a small region of relatively less shear allowing the system to maintain a current intensity of 35 knots.
Tropical storm 27W has gradually turned and tracked toward the west-northwestward on the southern periphery of a deep-layer subtropical ridge positioned to the north. By 12 hours, the system is expected to track toward the northwestward as the steering ridge to the north is forecast to reorient to a northwest-southeast direction, this will allow the system to stay a northwestward track through the end of the forecast period.
The JTWC intensity forecast calls for the system to maintain its current ts strength over the next 12 hours under marginal conditions. However, the upper level environment is forecast to become less favorable due to upper-level convergence, along with mid-level dry air entrainment.
These unfavorable environmental characteristics will result in a slow weakening trend after 12 hours. The environmental conditions will continue to degrade further with dissipation just to the east of the southeastern Philippines by 48 hours.