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Tropical Storm Nana Special Discussion Number   2
NWS National Hurricane Center Miami FL       AL162020
100 PM EDT Tue Sep 01 2020
 
An Air Force Reserve reconnaissance aircraft investigating the 
vigorous disturbance south of Jamaica this morning has found that 
the system has a well-defined, closed circulation center. The 
aircraft also measured 60 kt at 925 mb in the northeastern quadrant 
and reliable SFMR surface winds of 45 kt. Based on these data, the 
system has been upgraded to Tropical Storm Nana, the 14th named 
tropical storm of the 2020 Atlantic hurricane season.
 
The initial motion estimate is an uncertain 280/14 kt, No 
significant changes were made to the previous track forecast. 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.
 
Nana has developed a well-defined upper-level anticyclone, with 
outflow gradually improving in all quadrants. 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. Some dry air 
intrusions might hinder development for the next 24 hours or so, but 
the global and regional models still indicate that the atmosphere 
will moisten thereafter, and continue to moisten right up until 
landfall. Based on the higher initial intensity and the mostly 
favorable environmental conditions expected after 24 hours, the peak 
forecast intensity has been increased to 65 kt at 48 hours, just 
prior to landfall. 
 
Due to the Nana's expected proximity to Belize in 48 hours, a 
Tropical Storm Watch has been issued for that country. Additional 
watches and possible warnings will likely be required later today 
for Guatemala and the southern portion of the Yucatan Peninsula.

KEY MESSAGES:

1. Tropical Storm Nana is now forecast to be a hurricane as it 
approaches the coast, and interests in Honduras, Guatemala, 
Belize and Yucatan 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  01/1700Z 16.6N  77.9W   45 KT  50 MPH
 12H  02/0000Z 16.6N  79.5W   50 KT  60 MPH
 24H  02/1200Z 16.7N  82.3W   55 KT  65 MPH
 36H  03/0000Z 16.8N  85.1W   60 KT  70 MPH
 48H  03/1200Z 16.8N  87.4W   65 KT  75 MPH
 60H  04/0000Z 16.5N  89.6W   30 KT  35 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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