189 WTPZ42 KNHC 040251 TCDEP2 Hurricane Lorena Discussion Number 9 NWS National Hurricane Center Miami FL EP122025 800 PM MST Wed Sep 03 2025 Objective satellite intensity estimates from UW-CIMSS (ADT, AiDT, and SATCON) have increased by 5 to 10 kt since the Air Force Reserve reconnaissance mission into Lorena earlier this afternoon. Since the plane's data suggested an intensity of 70 kt at that time, the current intensity is estimated to be about 75 kt. That said, Lorena is probably at its peak intensity. There are already signs in conventional and microwave satellite imagery that vertical shear is beginning to strengthen, with a sharpening of the southern side of the upper-level cloud pattern and some tilt of the circulation with height. The shear is forecast to gradually increase over the next couple of days, and Lorena will also be moving over waters colder than 26 degrees Celsius in about 6 to 12 hours. Therefore, quick weakening is shown in the official forecast. Lorena continues to move toward the northwest, or 310 degrees, but at a slightly slower 10 kt. As the cyclone moves farther into a break in the subtropical ridge, it is expected to turn northward and slow down further by Thursday evening, and then move only slowly north-northeastward into the weekend. The 18z GFS run is finally playing the same tune as much of the other guidance, showing Lorena quickly decoupling as the shear removes its deep convection and leaving the low-level center drifting toward the west coast of Baja California Sur. Now that there is near-unanimous agreement that Lorena is unlikely to move quickly as a deep system toward northwestern Mexico, the NHC track forecast has been slowed down significantly, blending the previous forecast with the most recent HCCA and TVCE consensus aids. This new forecast brings Lorena's center to the west coast of Baja California Sur in about 48 hours as a weakening tropical cyclone, with the system reaching the east coast of the peninsula as a remnant low in about 60 hours. However, based on the latest GFS- and ECMWF-based simulated satellite imagery, the transition to a remnant low could occur earlier than that. Even if Lorena weakens and becomes a remnant low earlier than previously predicted, abundant moisture will continue to stream northeastward away from the cyclone. Because of that, there is still a significant risk of heavy rainfall and flash flooding across portions of Baja California Sur, Sonora, and southern Arizona and New Mexico. Key Messages: 1. Heavy rainfall associated with Lorena will continue to impact Baja California Sur and shift into southwestern Sonora Thursday. This will increase the risk of life-threatening flash floods and mudslides across northwest Mexico. 2. Moisture from Lorena will contribute to heavy rainfall concerns across Arizona and southwest New Mexico through Saturday. Isolated to scattered instances of flash flooding are possible across Arizona into Saturday. 3. The center of Lorena is forecast to move parallel to, but offshore of, the southwest coast of the Baja California Peninsula through Thursday, and then move closer to the west-central coast of the peninsula Thursday night and Friday. Regardless of the exact track, tropical storm conditions are likely along portions of the coast of Baja California Sur where a Tropical Storm Warning is in effect. Tropical storm conditions are also possible late Friday along the east coast of the Baja California peninsula, where a Tropical Storm Watch is in effect. 4. Life-threatening surf and rip current conditions will affect portions of the southern and western coasts of Baja California Sur during the next couple of days. FORECAST POSITIONS AND MAX WINDS INIT 04/0300Z 23.4N 113.2W 75 KT 85 MPH 12H 04/1200Z 24.1N 113.9W 65 KT 75 MPH 24H 05/0000Z 25.0N 114.1W 55 KT 65 MPH 36H 05/1200Z 26.0N 113.8W 45 KT 50 MPH 48H 06/0000Z 27.0N 113.4W 35 KT 40 MPH 60H 06/1200Z 28.0N 113.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 07/0000Z 28.8N 112.9W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 08/0000Z...DISSIPATED $$ Forecaster Berg
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