Tropical Cyclone Discussion
634 WTPA42 PHFO 220842 TCDCP2 Hurricane Lala Discussion Number 40 NWS Central Pacific Hurricane Center Honolulu HI CP012026 Issued by NWS National Hurricane Center Miami FL 1100 PM HST Fri Aug 21 2026 Lala's structure has evolved over the past 6-12 hours due to interaction with an upper-level trough to its west and southwest. Deep convection has been sheared away from the center due to nearly 30 kt of south-southwesterly shear, and moderate convection now wraps around the northern and western side of the circulation, very similar to the structure of an occluded extratropical low. Dvorak Current Intensity numbers from HFO and JTWC are still 4.5/77 kt, and given that winds can be slow to decrease when a tropical cyclone positively interacts with an upper-level trough, the current intensity estimate remains 75 kt. It is estimated that Lala's wind field has also expanded as a result of the trough interaction. A pair of ASCAT passes should hit the cyclone soon to give us a better estimate of Lala's intensity and size. The interaction with the trough has also caused Lala to turn and temporarily accelerate toward the northwest (325/12 kt). A mid-level ridge to the northeast should force the cyclone on a northwestward trajectory for the next 3 days, but the steering is so weak that Lala is likely to slow down considerably, only moving at 4-5 kt on Sunday and Monday. A motion toward the north-northwest could occur by Tuesday and Wednesday as the ridge shifts east of Lala, but there is model spread regarding the degree and speed of that turn. The NHC track forecast lies just left of the center of the guidance envelope, leaning toward the HCCA and GDMI guidance, and is also not very different from the previous forecast. Deep-layer shear is forecast to fall to 10 kt or less in about 12 hours once Lala becomes embedded within the larger-scale longwave trough. Since the hurricane is expected to slow down, water temperatures and atmospheric instability are only expected to gradually decrease during the next few days, which should allow for at least moderate convection to continue. The NHC intensity forecast continues to show gradual weakening, generally close to the IVCN intensity consensus, and Lala could still be a tropical cyclone at the end of the 5-day forecast period. FORECAST POSITIONS AND MAX WINDS INIT 22/0900Z 30.3N 172.0W 75 KT 85 MPH 12H 22/1800Z 31.3N 172.7W 70 KT 80 MPH 24H 23/0600Z 32.2N 173.6W 65 KT 75 MPH 36H 23/1800Z 33.0N 174.4W 60 KT 70 MPH 48H 24/0600Z 33.6N 175.0W 55 KT 65 MPH 60H 24/1800Z 34.3N 175.6W 50 KT 60 MPH 72H 25/0600Z 35.1N 176.4W 45 KT 50 MPH 96H 26/0600Z 36.8N 178.1W 45 KT 50 MPH 120H 27/0600Z 38.9N 179.4W 40 KT 45 MPH