310 WTPZ44 KNHC 030849 TCDEP4 Tropical Storm Bonnie Discussion Number 23 NWS National Hurricane Center Miami FL EP042022 400 AM CDT Sun Jul 03 2022 Geostationary satellite imagery shows a large, persistent convective cloud mass displaced to the west of Bonnie's low-level center by some easterly shear. Infrared cloud top temperatures colder than -80 deg C indicate the convection remains vigorous, and it is showing more signs of curvature in recent imagery after appearing somewhat amorphous overnight. Unfortunately, no recent microwave or scatterometer data are available to assess recent structural changes. A blend of the subjective Dvorak estimates from TAFB and SAB supports holding the initial intensity at 50 kt. Environmental conditions appear favorable for Bonnie to strengthen during the next few days. In the near term, the deep-layer easterly shear is forecast to slightly diminish while Bonnie traverses warm SSTs of 28-29 deg C within a moist mid-level environment. The official NHC forecast calls for Bonnie to become a hurricane by Monday and continue strengthening during the next 48 h or so. While not explicitly forecast, the SHIPS guidance suggests some increased potential for rapid intensification. The latest NHC forecast is raised slightly higher than the previous one, in line with the IVCN consensus aid. Increasing northeasterly shear and gradually cooler SSTs along its forecast track should cause Bonnie's intensity to level off and gradually decrease by days 4-5. Bonnie is still moving quickly westward at 275/14 kt. A mid-level ridge to the north of the cyclone should steer Bonnie westward to west-northwestward during the next several days, roughly parallel to the coast of southern Mexico. The track guidance remains in excellent agreement, and the latest NHC forecast is very similar to the previous one given the tightly clustered track models. Once again, this forecast keeps the center of Bonnie far enough offshore that the tropical-storm-force winds are not forecast to reach the coast of Central America or Mexico at this time. However, interests in coastal El Salvador, Guatemala, and southern and southwestern Mexico should closely monitor updates to Bonnie's forecast track, as a slight northward adjustment to the track could require tropical storm watches for portions of this coastline. KEY MESSAGES: 1. Areas of heavy rainfall are possible across portions of El Salvador, Guatemala, and southern Mexico during the next couple of days. This rainfall could cause some instances of flash flooding and mudslides across the region. 2. Interests along the coasts of Guatemala and southern and southwestern Mexico should monitor the progress of this system. While the center of Bonnie is forecast to stay offshore, any northward adjustment in the track forecast could require the issuance of a tropical storm watch for part of this area. FORECAST POSITIONS AND MAX WINDS INIT 03/0900Z 11.6N 90.6W 50 KT 60 MPH 12H 03/1800Z 12.1N 92.7W 55 KT 65 MPH 24H 04/0600Z 12.8N 95.6W 65 KT 75 MPH 36H 04/1800Z 13.6N 98.5W 75 KT 85 MPH 48H 05/0600Z 14.5N 101.5W 85 KT 100 MPH 60H 05/1800Z 15.2N 104.3W 85 KT 100 MPH 72H 06/0600Z 15.6N 106.7W 80 KT 90 MPH 96H 07/0600Z 16.0N 111.0W 80 KT 90 MPH 120H 08/0600Z 16.5N 115.5W 75 KT 85 MPH $$ Forecaster Reinhart