Issued at 800 AM MST Wed Sep 03 2025
000 WTPZ42 KNHC 031458 TCDEP2 Hurricane Lorena Discussion Number 7 NWS National Hurricane Center Miami FL EP122025 800 AM MST Wed Sep 03 2025 Satellite imagery and radar data from the Los Cabos radar in Mexico indicate that Lorena continues to become better organized. Radar imagery shows Lorena's eye becoming better defined, with a completely closed and circular eyewall. Dvorak estimates from TAFB and SAB were both T-4.0/65 kt, with the UW-CIMSS numbers ranging from 55-68 kt. However, the improvement over the last few hours seen in radar images and GOES West satellite images suggest that Lorena is likely stronger now. The initial intensity is estimated at 70 kt, and it is possible this may be a bit conservative. An Air Force Reserve reconnaissance aircraft is currently enroute to Lorena, which should provide a better estimate of the intensity in a couple of hours from now. Lorena has rapidly intensified over the past 24 hours. Continued rapid strengthening is likely for another 12 to 18 hours as Lorena remains over warm water and in low wind shear conditions, and the peak intensity forecast of 85 kt is maintained. By 24 hours, the hurricane is expected to cross the 26C sea-surface temperature isotherm while southwesterly wind shear also begins to significantly increase. These conditions are expected to lead to rapid weakening beginning by Thursday afternoon. The official forecast is above most of the intensity guidance for the first 24 hours, but is closer to the consensus aids thereafter. The initial motion is faster now toward the northwest, or 320/14 kt. Not much has changed with the track forecast reasoning. There are still two camps of models. The majority of the guidance, including the GFS, shows Lorena progressing faster and farther east, with landfall in Baja California Sur followed by a turn toward the northeast. But a significant minority of models, including the ECMWF, CMC, and UKMET, slow down Lorena immediately, with a track farther west, and then dissipate the system over water without making landfall. The steering is such that a stronger cyclone would be more likely to be in the faster and farther east camp of models. However, if the hurricane rapidly weakens by Thursday night and starts to decouple due to the aforementioned increasing southwesterly shear, then the low-level circulation could potentially get left behind. The new NHC forecast shows a faster forward motion over the next 36 hours with a track slightly to the right of the previous NHC track. Due to the rightward shift, the chance of tropical storm force winds impacting portions of Baja California Sur is increasing. Additionally, there is very high confidence that heavy rainfall amounts leading to significant flooding will occur in Baja California Sur, especially since the southwesterly upper-level winds favor deep convection to the right side of Lorena by late Thursday. At 48 h and beyond, the new NHC forecast is similar to, but slightly to the left of, the previous NHC forecast track. Key Messages: 1. Heavy rainfall associated with Tropical Storm Lorena will continue to impact Baja California Sur, moving into southeastern Baja California and southwestern Sonora by Thursday, and contributing to heavy rainfall concerns across Arizona from late Wednesday through Friday. This will increase the risk of life-threatening flash floods and mudslides across Mexico, especially in areas of higher terrain. Isolated to scattered instances of flash flooding are possible across Arizona through Friday. 2. The center of Lorena is forecast to move parallel to, but offshore of, the southwest coast of the Baja Peninsula today, and then move closer to the west-central coast of the peninsula on Thursday. Regardless of the exact track, tropical storm conditions are likely along portions of the coast of Baja California Sur where a Tropical Storm Warning has been issued. Tropical Storm conditions are also possible through tonight along the southwestern coast of Baja California Sur where a Tropical Storm Watch is in effect. Interests elsewhere in Baja California Sur should closely monitor the latest forecast updates. 3. 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 03/1500Z 22.3N 111.6W 70 KT 80 MPH 12H 04/0000Z 23.4N 112.7W 85 KT 100 MPH 24H 04/1200Z 24.5N 113.7W 80 KT 90 MPH 36H 05/0000Z 25.6N 113.9W 65 KT 75 MPH 48H 05/1200Z 26.4N 113.9W 50 KT 60 MPH 60H 06/0000Z 27.5N 113.5W 40 KT 45 MPH 72H 06/1200Z 28.4N 112.8W 35 KT 40 MPH 96H 07/1200Z 30.4N 110.6W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 08/1200Z...DISSIPATED $$ Forecaster Hagen
