Tropical Storm Rene Discussion Number   4
NWS National Hurricane Center Miami FL       AL182020
200 AM CVT Tue Sep 08 2020

Convection has noticeably waned during the past few hours as Rene's 
center moved directly over Boa Vista island between 07/2200 UTC and 
08/0000 UTC. The highest observed wind speed thus far has been a 
10-minute average wind of 25 kt at Sal/GVAC. Satellite intensity 
estimates range from 35 kt from TAFB to 30 kt from SAB. A 07/2323 
UTC ASCAT-B overpass indicated peak winds of 27 kt, but land 
obscuration likely has resulted in some missed higher wind speeds. 
For now, the intensity will remain at 35 kt.

The initial motion is 280/12 kt. A westward motion is expected 
today, followed by a west-northwestward motion through Thursday as 
Rene rounds the southwestern periphery of a deep-layer subtropical 
ridge. On days 4 ad 5, the cyclone is forecast to move more slowly 
northwestward to north-northwestward through a weakness in the 
aforementioned ridge. The track guidance appears to have stabilized 
on the latest set of model runs and, thus, the new NHC forecast 
track is very similar to the previous advisory track, and lies close 
to a blend of the TVCA and NOAA-HCCA consensus track models.

The intensity forecast was held steady for the next 12 h or so 
until Rene clears the negative influence of the mountainous Cabo 
Verde Islands. It's possible that Rene could even weaken by the time 
it passes the western Cabo Verde Islands. Thereafter, however, 
environmental conditions appear conducive for the cyclone to 
gradually strengthen, becoming a hurricane on day 3. By days 4 and 
5, an increase in southwesterly vertical wind shear is expected to 
induce a weakening trend. The new NHC intensity forecast is similar 
to a blend of the IVCN and the HCCA intensity consensus models, 
and the GFS model.

Key Messages:

1. Rene is expected to produce tropical storm conditions across
portions of the Cabo Verde Islands this morning and afternoon.  A
Tropical Storm Warning is in effect for those islands.

2. Rene will bring locally heavy rainfall to portions of the Cabo
Verde Islands through this afternoon.


FORECAST POSITIONS AND MAX WINDS

INIT  08/0300Z 16.2N  23.5W   35 KT  40 MPH
12H  08/1200Z 16.5N  25.5W   35 KT  40 MPH
24H  09/0000Z 16.8N  28.2W   45 KT  50 MPH
36H  09/1200Z 17.3N  30.9W   50 KT  60 MPH
48H  10/0000Z 18.2N  33.6W   60 KT  70 MPH
60H  10/1200Z 19.1N  36.1W   65 KT  75 MPH
72H  11/0000Z 20.2N  38.3W   70 KT  80 MPH
96H  12/0000Z 23.1N  41.9W   65 KT  75 MPH
120H  13/0000Z 27.6N  44.1W   55 KT  65 MPH

$$
Forecaster Stewart