Tropical Cyclone Discussion
677 WTPA44 PHFO 092035 TCDCP4 Tropical Storm Lowell Discussion Number 55 NWS Central Pacific Hurricane Center Honolulu HI EP122026 Issued by NWS National Hurricane Center Miami FL 1100 AM HST Wed Sep 09 2026 Lowell is dealing with moderate wind shear and dry air. Recent satellite imagery reveals that earlier deep convection has collapsed, with only shallow convection remaining sheared to the eastern side of the circulation. The latest subjective Dvorak intensity estimates from PHFO and JTWC have decreased to T2.5/35 kt, which is consistent with the system's degraded satellite presentation. UW-CIMSS objective intensity estimates currently range from 39 to 49 kt. Metop-B and Metop-C scatterometer passes are anticipated over Lowell near the advisory time, which will help better assess the current intensity and wind radii structure. Although current satellite estimates have decreased, the initial intensity is held at 50 kt for this advisory, which may be generous. Subsequent adjustments will await the incoming scatterometer wind data. Lowell is expected to remain within a dry environment with moderate vertical wind shear. Model-simulated infrared imagery suggests that Lowell will continue to produce intermittent bursts of deep convection over the next several days, aided by some upper-level divergence in about 48 hours. The official NHC intensity forecast follows the latest consensus model guidance, depicting a gradual weakening of the system throughout the forecast period. By the end of the period, the cyclone is forecast to move over cooler sea surface temperatures while continuing to deal with dry air and moderate shear. Although some uncertainty remains late in the period due to the system's eventual track and intermittent convective bursts, these hostile environmental conditions should cause Lowell to become a post-tropical cyclone by day 4. The initial motion is northwestward, or 320/12 kt. Lowell should gradually turn west-northwestward and then westward, steered by a building mid-level ridge to the north and east. In a few days, the cyclone is forecast to round the western periphery of the ridge and slow forward speed. This decrease in forward speed will occur as the steering pattern collapses, leaving Lowell caught between high-pressure ridges over the northwestern and northeastern Pacific. Track model guidance begins to diverge considerably late in the period. This spread in the guidance largely depends on the vertical depth of the cyclone, and if the system remains a shallow low, it could begin to move southwestward, steered by the low-level flow on the eastern edge of the northwestern Pacific ridge. The official NHC track forecast lies near the HCCA and GDMI consensus aids in the near term, and then shifts toward the simple consensus later in the period, reflecting the higher uncertainty toward the end of the forecast cycle. KEY MESSAGES: 1. Post-storm safety: Follow advice of local officials and avoid areas of downed power lines and flooding. Ensure generators are properly ventilated and placed outside at least 20 feet away from dwellings and garages to avoid carbon monoxide poisoning. During clean up, be careful when using chainsaws and power tools. Drink plenty of water to avoid heat exhaustion. FORECAST POSITIONS AND MAX WINDS INIT 09/2100Z 28.9N 163.7W 50 KT 60 MPH 12H 10/0600Z 29.3N 165.7W 45 KT 50 MPH 24H 10/1800Z 29.3N 168.1W 45 KT 50 MPH 36H 11/0600Z 29.3N 170.5W 40 KT 45 MPH 48H 11/1800Z 29.9N 171.7W 40 KT 45 MPH 60H 12/0600Z 30.9N 171.8W 40 KT 45 MPH 72H 12/1800Z 32.3N 172.3W 40 KT 45 MPH 96H 13/1800Z 33.2N 174.8W 35 KT 40 MPH...POST-TROPICAL 120H 14/1800Z 32.7N 176.0W 30 KT 35 MPH...POST-TROP/REMNT LOW