Eastern Pacific Basin Tropical Cyclones

Tropical Storm Bonnie Forecast Discussion


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




Source link