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Tropical Storm Rene Discussion Number  21
NWS National Hurricane Center Miami FL       AL182020
500 AM AST Sat Sep 12 2020
 
Deep convection associated with Rene appears to have lost some
organization overnight.  Although there have been several pulsating
bursts of convection overnight, the convection that was persistent
over the center during the evening is now confined to the southern 
portion of the circulation.  A blend of the latest subjective and 
objective satellite intensity estimates yields an initial intensity 
of 35 kt, but this could be generous.  ASCAT data later this 
morning should help to determine if Rene is still a topical storm. 
Mid-level dry air appears to be the primary reason why Rene has 
struggled to strengthen over the past few days, and although the 
shear is expected to remain low today, the dry air is likely to 
prevent strengthening.  On Sunday, Rene is forecast to approach an 
area of strong west-northwesterly flow aloft, and this increase is 
shear is likely to cause the cyclone to weaken.  Most of the global 
models continue to significantly weaken Rene early next week, and 
both the ECMWF and GFS suggest that the cyclone will degenerate 
into a trough of low pressure by days 4 or 5.  The NHC forecast 
continues to maintain Rene as a tropical cyclone throughout the 
forecast period, but if the current trends it is becoming unlikely 
that Rene will survive as a tropical cyclone for the entire 5-day 
period. 
 
Rene has turned northwestward and is now moving at 305/13 kt. 
A northwestward motion around the western periphery of a mid-level 
ridge over the eastern Atlantic should continue for another 12 to 
24 hours, but by late Sunday Rene is forecast to slow down as ridge 
of high pressure builds to the northwest and north of the cyclone. 
Later in the period, Rene is forecast to turn westward and then 
southwestward under the influence of the building ridge. The track 
guidance remains in fairly good agreement, and no significant 
changes to the official forecaster were required. 

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  12/0900Z 22.5N  43.5W   35 KT  40 MPH
 12H  12/1800Z 23.7N  44.9W   35 KT  40 MPH
 24H  13/0600Z 25.4N  46.3W   35 KT  40 MPH
 36H  13/1800Z 26.6N  47.3W   35 KT  40 MPH
 48H  14/0600Z 27.2N  47.7W   30 KT  35 MPH
 60H  14/1800Z 27.1N  48.1W   30 KT  35 MPH
 72H  15/0600Z 26.7N  49.1W   30 KT  35 MPH
 96H  16/0600Z 25.5N  52.0W   30 KT  35 MPH
120H  17/0600Z 24.7N  55.0W   30 KT  35 MPH
 
$$
Forecaster Brown
 
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