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Potential Tropical Cyclone Sixteen Discussion Number   1
NWS National Hurricane Center Miami FL       AL162020
1100 AM EDT Tue Sep 01 2020
 
An Air Force Reserve reconnaissance aircraft is currently 
investigating the vigorous tropical disturbance located south of 
Jamaica that the NHC has been tracking the past few days across the 
Caribbean Sea. An earlier report of 35 kt winds this morning from 
ship MAOR4 is the basis for the 35-kt initial intensity on 
Potential Tropical Cyclone Sixteen. (PTC-16)
 
The initial motion estimate is an uncertain 285/16 kt, based mainly
on past scatterometer surface wind data and passive microwave
satellite fix data. A strong deep-layer to the north of the system
is expected to build slowly westward over the next few days,
keeping the disturbance moving in a general west-northwestward to
westward direction through 48 hours, followed by a turn toward the
west-southwest shortly thereafter when the system will be inland
over Central America. The NHC official forecast track lies close
to a blend of the simple consensus models TVCN and GFEX, and the
corrected-consensus model HCCA.
 
The disturbance has already developed an upper-level anticyclone, 
with outflow only restricted in the northeastern quadrant due to 
northeasterly shear of about 15 kt. This modest northeasterly to 
easterly vertical wind shear is expected to gradually subside to 
less than 10 kt by 48 hours, which should allow for at least some 
slow but steady strengthening, given that sea-surface temperatures 
(SST) will be 29.5-30.5 deg C along the track. Occasional intrusions 
of dry mid-level air might hinder development for the next 24-36 
hours, but model guidance shows that the atmosphere is expected to 
moisten thereafter and right up until landfall. The official 
intensity forecast is similar to the consensus of the intensity 
guidance through 24 hours, and then is a little above the consensus 
at 36 h and 48 h due to the very warm waters, moistening atmosphere, 
and low shear conditions. The statistical SHIPS guidance suggests 
that the cyclone could reach hurricane strength just prior to 
landfall. This alternate scenario will be evaluated on the next 
advisory cycle.
 
Due to the system's expected proximity to the north coast of 
Honduras and Roatan Island, a Tropical Storm Watch has been 
issued for those areas. Additional watches and possible warnings 
will likely be required later today for Guatemala, Belize, and the 
southern portion of the Yucatan Peninsula.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  01/1500Z 16.1N  77.5W   35 KT  40 MPH...POTENTIAL TROP CYCLONE
 12H  02/0000Z 16.4N  79.6W   35 KT  40 MPH...TROPICAL STORM
 24H  02/1200Z 16.6N  82.3W   40 KT  45 MPH
 36H  03/0000Z 16.7N  85.1W   45 KT  50 MPH
 48H  03/1200Z 16.8N  87.4W   50 KT  60 MPH
 60H  04/0000Z 16.5N  89.6W   25 KT  30 MPH...INLAND
 72H  04/1200Z 15.7N  91.7W   15 KT  15 MPH...POST-TROP/REMNT LOW
 96H  05/1200Z...DISSIPATED
 
$$
Forecaster Stewart
 
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