Hurricane Rosa Expected To Make Landfall in Baja California

9/30/18: Hurricane Rosa is located in the Eastern Pacific Ocean and it moving towards Baja California. Rosa is a category 1 hurricane with sustained winds of 85 mph. While expected to continue to weaken, Rosa will bring torrential downpours as well as damaging winds to the Southwest. Rosa is expected to downgrade to a tropical storm by the time it makes landfall on Monday. After making landfall, Rosa is expected to continue on a northeastward track towards Arizona. Currently, hurricane force winds extend outward of 30 miles form the center. Due to the mountainous region, the heavy rainfall can produce life-threatening flash flooding and landslides. High surf as well as storm surge is also a threat as Rosa moves closer to land.
The key messages from the National Hurricane Center are as follows:

The main hazard expected from Rosa or its remnants is very heavy rainfall in Baja California, northwestern Sonora, and the U.S. Desert Southwest. These rains are expected to produce life-threatening flash flooding and debris flows in the deserts, and landslides in mountainous terrain.

Tropical storm conditions are expected over portions of the central and northern Baja California peninsula on Monday, possibly spreading to the northern Gulf of California Monday night. Interests in those locations should monitor the progress of Rosa.

The forecast discussion from the National Hurricane Center is as follows:

This initial motion estimate is 005/10 kt. Rosa is forecast to continue moving northward around the western edge of a deep-layer ridge for the next 24 h or so, followed by a turn toward the north-northeast on Tuesday as a mid-/upper-level trough approaches from the west. As the low- and upper-level circulations continue to decouple, Rosa should essentially maintain its current forward speed until landfall occurs in 36-48 hours due to the cyclone not being influenced by the faster deep-layer steering flow. The new NHC track forecast is a little slower than the previous advisory track, and closely follows the consensus models HCCA and IVCN. A 72-hour forecast position continues to be provided for continuity purposes, but Rosa’s surface circulation is likely to dissipate before that time over northwestern Mexico or southern Arizona, with the mid-level remnants continuing northward across the Desert Southwest and Intermountain West.

Rosa is now moving over waters colder than 25ºC, with colder water near 22ºC ahead of the cyclone just prior to landfall. The combination of increasing wind shear, cooler waters and drier and more stable air being entrained from the west should result in steady or even rapid weakening of the cyclone until landfall occurs. The official forecast follows the sharp weakening trend indicated in the previous advisory, which is supported by the latest intensity guidance. Rosa is expected to devolve into an exposed low-level center with the associated deep convection being sheared off to its north and northeast by the time it is nearing the Baja California coast on Monday.  However, it will take some time for the circulation to spin down, and Rosa is still expected to bring tropical-storm-force winds to portions of Baja California in 36-48 hours.

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? 2018 Meteorologist Brandie Cantrell