Tropical Cyclone Discussion
406 WTPA43 PHFO 261436 TCDCP3 Tropical Depression Olana Discussion Number 5 NWS Central Pacific Hurricane Center Honolulu HI CP032026 Issued by NWS National Hurricane Center Miami FL 500 AM HST Mon Oct 26 2026 Olana's structure on satellite imagery has rapidly degraded early this morning. The deep convection that had been near the center yesterday has separated well off to the northeast, leaving behind a broad low-level swirl that is south of the previous satellite estimates. This degradation in structure is likely due to increasing southwesterly vertical wind shear that has led to the circulation decoupling vertically overnight. Consequently, subjective and objective intensity estimates are decreasing, and Olana is being downgraded to a tropical depression in this advisory with maximum sustained winds of 30 kt. As noted above, Olana's circulation has been moving south of the previous forecast track, and the initial motion is slowly off to the southeast or 140 degrees at 4 kt. Now that the circulation has become vertically shallow, its motion will mostly be governed by light and variable low-level steering, due to the competing influences of a westerly wind burst to Olana's south and a weak low-level ridge to the cyclone's north. The NHC track forecast has been adjusted southward, mostly due to the change in the initial position. This track attempts to blend the faster and eastward HFIP Corrected Consensus Approach (HCCA) with the much slower ECMWF (EMXI) track aids. Increasing vertical wind shear from an upper-level trough, coupled with dry air entrainment should ultimately lead to Olana's demise over the next couple of days. Given the current degraded structure, the latest forecast now shows the tropical cyclone degenerating into a remnant low in 24 hours, and this could occur sooner if convection does not soon return closer to the circulation center. Thereafter, the model guidance shows the upper-level trough cutting off and interacting with Olana's remnants. This could result in some baroclinic redevelopment in 3-4 days, though the majority of the guidance shows Olana's circulation becoming too elongated to be trackable before that time, and dissipation is now shown in 60 hours. Based on the latest forecast, Olana is expected to dissipate prior to reaching Johnston Atoll. However, the sheared shower and thunderstorm activity displaced well northeast of the center could affect the area over the next couple of days, producing gusty winds and heavy rainfall. FORECAST POSITIONS AND MAX WINDS INIT 26/1500Z 13.9N 176.8W 30 KT 35 MPH 12H 27/0000Z 13.7N 176.5W 25 KT 30 MPH 24H 27/1200Z 13.5N 176.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 36H 28/0000Z 13.8N 175.1W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 28/1200Z 14.3N 174.6W 25 KT 30 MPH...POST-TROP/REMNT LOW 60H 29/0000Z...DISSIPATED