000 WTPZ42 KNHC 051438 TCDEP2 Tropical Storm Kay Discussion Number 5 NWS National Hurricane Center Miami FL EP122022 900 AM MDT Mon Sep 05 2022 Kay continues to produce very deep convection, but the storm is asymmetric with its center estimated to be on the north side of the main area of thunderstorms. The latest satellite intensity estimates range from 45 to 55 kt, and based on that data, the initial intensity is held at 50 kt for this advisory. Kay is a sprawling tropical storm with its outer rain bands extending as far out as 300 n mi from the center. The northern rain bands are affecting the coast of southwestern Mexico, where tropical-storm-force wind gusts are likely occurring. An Air Force Hurricane Hunter aircraft is scheduled to investigate Kay later today. The storm is moving westward at 13 kt and continues to be steered by a mid-level ridge to its north. The model guidance remains in fairly good agreement that a turn to the west-northwest is likely to begin tonight followed by a northwestward motion by Tuesday night. Although this should take the core of Kay well to the west of the southern tip of the Baja California peninsula, tropical storm conditions are possible there by early Wednesday given its expansive wind field. Kay will likely be very near the west-central portion of the peninsula on Thursday and Friday, and hurricane watches could be required for that region later today or tomorrow. The spread in the GFS and ECMWF ensemble members is basically the same as it was yesterday and shows solutions spanning a region from over central Baja to a few hundred miles west of the peninsula. A turn back to the left is expected by the end of the forecast period due to a mid-level ridge to its north. Overall, the NHC track forecast has changed little this cycle and lies near the HCCA model and a consensus of the GFS and ECMWF. Kay is still experiencing moderate north-northeasterly shear, which is causing its asymmetric cloud pattern. This shear is expected to persist, which should prevent rapid intensification. Nonetheless, given the warm SSTs and high mid-level moisture, continued steady strengthening is likely to continue during the next couple of days and Kay will likely become a hurricane tonight or on Tuesday. Beyond a couple of days, progressively cooler SSTs and a drier air mass should end the strengthening trend and induce steady weakening. The NHC intensity forecast is similar to the previous one and lies a little above the HCCA and IVCN guidance, but below the latest SHIPS output. KEY MESSAGES: 1. Although the center of Kay is forecast to stay offshore of southwest mainland Mexico, gusts to tropical-storm-force and rough surf along the coast are expected through Tuesday. In addition, heavy rainfall could lead to flash flooding, including landslides, across portions of the Mexican Riviera and western Mexico through Wednesday night. 2. Tropical storm conditions are possible across the southern Baja California peninsula by early Wednesday, where a Tropical Storm Watch has been issued. 3. Kay is expected to be a hurricane when it nears the central portion of the Baja California peninsula later this week. While the details of the long-range track and intensity forecasts remain uncertain, there is increasing risk of significant wind, surf, and rainfall impacts there, and a tropical storm or hurricane watch could be issued for that region later today or Tuesday. FORECAST POSITIONS AND MAX WINDS INIT 05/1500Z 15.8N 106.4W 50 KT 60 MPH 12H 06/0000Z 16.2N 107.8W 60 KT 70 MPH 24H 06/1200Z 17.3N 109.6W 70 KT 80 MPH 36H 07/0000Z 18.7N 111.2W 80 KT 90 MPH 48H 07/1200Z 20.2N 112.4W 90 KT 105 MPH 60H 08/0000Z 22.0N 113.3W 90 KT 105 MPH 72H 08/1200Z 24.0N 114.0W 80 KT 90 MPH 96H 09/1200Z 27.5N 115.7W 60 KT 70 MPH 120H 10/1200Z 29.7N 119.1W 45 KT 50 MPH $$ Forecaster Cangialosi