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Tropical Storm Nana Discussion Number   5
NWS National Hurricane Center Miami FL       AL162020
500 AM EDT Wed Sep 02 2020

Nana's Central Dense Overcast has become a little better defined, 
with cloud tops to -80 deg C or colder.  Upper-level outflow 
continues to be somewhat inhibited over the northern portion of the 
circulation.  SFMR-observed surface winds and adjusted flight-level 
winds from an Air Force Hurricane Hunter aircraft indicated an 
intensity of 50 kt.  Although northerly shear is likely to limit 
intensification, the environment is conducive enough for Nana to 
strengthen into a hurricane later today.  The official intensity 
forecast is close to the Decay-SHIPS prediction based on the ECMWF 
global model forecast fields.
 
Center fixes from the aircraft indicate that the motion continues 
to be generally westward, or 270/16 kt, to the south of a strong 
mid-level high pressure area.  Over the next couple of days, the 
ridge is expected to be maintained or to build a little more to the 
west.  This should keep Nana on a westward or slightly south-of-west 
track until it moves into Central America.  The official track 
forecast is close to the previous one and also very close to the 
latest Florida State University Superensemble prediction.

Observations from the aircraft and NOAA data buoy 42057 indicate 
that Nana is a rather small tropical cyclone, with 
tropical-storm-force winds extending 60 n mi or less from the 
center.
 
KEY MESSAGES:
 
1. Tropical Storm Nana is forecast to be a hurricane as it
approaches the coast, and interests in Honduras, Guatemala,
Belize, and the Yucatan Peninsula should closely monitor the 
progress of this storm.  Strong winds, dangerous storm surge and 
very heavy rainfall causing flash flooding are becoming more likely 
from Nana.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  02/0900Z 17.0N  82.7W   50 KT  60 MPH
 12H  02/1800Z 16.9N  85.0W   60 KT  70 MPH
 24H  03/0600Z 16.8N  87.6W   65 KT  75 MPH
 36H  03/1800Z 16.5N  89.8W   50 KT  60 MPH...INLAND
 48H  04/0600Z 16.4N  92.1W   30 KT  35 MPH...INLAND
 60H  04/1800Z 16.1N  93.9W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  05/0600Z...DISSIPATED
 
$$
Forecaster Pasch
 
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