Eastern Pacific Basin Tropical Cyclones

Hurricane Bonnie Forecast Discussion


985 
WTPZ44 KNHC 041448
TCDEP4

Hurricane Bonnie Discussion Number  28
NWS National Hurricane Center Miami FL       EP042022
1000 AM CDT Mon Jul 04 2022

Bonnie's satellite presentation has improved this morning with a
ragged eye becoming more apparent in both infrared and visible
satellite imagery.  An earlier AMSR2 microwave overpass that
arrived after the release of the previous advisory, and more
recent SSMIS imagery revealed a fairly well-defined low- to
mid-level eye feature.  Subjective Dvorak estimates from both TAFB
and SAB are T4.5 or 77 kt.  Objective estimates from UW/CIMSS are
lagging a bit, but recent raw T-numbers have increased as the eye
has become better defined.  The advisory intensity is set at 80
kt, near the higher end of the estimates due to the continued
improvement in structure.

Bonnie's intensity forecast is a bit tricky this morning as
expected subtle changes in shear throughout the forecast
period could have larger-than-normal implications on the
forecast.  In the very near term, some additional strengthening is
likely while Bonnie remains within an area of moderate northeasterly
shear and otherwise favorable environmental conditions. The NHC
wind speed forecast is near the high end of the guidance during the
first 12-24 hours given the recent upward trend in organization. The
shear is forecast to increase on Tuesday, which the guidance 
suggests will cause Bonnie's intensity to plateau or perhaps 
fluctuate over the next 2-3 days.  By 72 hours, global models now 
indicate that the shear will decrease while the system is still 
over marginally warm water.  As a result, the NHC forecast keeps 
Bonnie's intensity slightly higher through 96 h than the previous 
advisory.  Shortly after that time, rapid weakening is likely to 
begin as the cyclone moves over waters less than 26C and into a 
less favorable thermodynamic environment.

Bonnie is moving briskly westward to west-northwestward with a
longer term motion of 285/16 kt.  The track forecast reasoning has
not changed over the past day or so.  Bonnie should continue to
move generally west-northwestward with some reduction in forward
speed while it is steered by a large mid-level to the north.  This
motion will take Bonnie roughly parallel to but well offshore the
coasts of southern and southwestern Mexico during the next day or
two. The latest NHC track forecast is again an update of the
previous advisory, and it remains close to the TVCE multi-model
consensus aid.

The forecast keeps tropical-storm-force winds associated with
Bonnie offshore the coast of southern and southwestern Mexico, but
coastal locations can still expect rough surf and the potential for
rip currents today and Tuesday as Bonnie passes offshore.


FORECAST POSITIONS AND MAX WINDS

INIT  04/1500Z 13.7N  99.0W   80 KT  90 MPH
 12H  05/0000Z 14.4N 101.2W   90 KT 105 MPH
 24H  05/1200Z 15.1N 104.0W   90 KT 105 MPH
 36H  06/0000Z 15.6N 106.4W   90 KT 105 MPH
 48H  06/1200Z 16.0N 108.6W   90 KT 105 MPH
 60H  07/0000Z 16.2N 110.7W   90 KT 105 MPH
 72H  07/1200Z 16.4N 112.8W   90 KT 105 MPH
 96H  08/1200Z 17.6N 117.8W   85 KT 100 MPH
120H  09/1200Z 19.1N 124.0W   65 KT  75 MPH

$$
Forecaster Brown




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