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Tropical Storm Nana Discussion Number   4
NWS National Hurricane Center Miami FL       AL162020
1100 PM EDT Tue Sep 01 2020
 
Deep convection redeveloped over the center of Nana during the late
afternoon and recent microwave imagery has revealed a small,
well-defined low-level eye-like feature, and convective banding
around the southwestern portion of the circulation.  An Air Force
Reserve hurricane hunter aircraft that has provided a couple of 
center fixes within the past hour or two has measured a peak 
850-mb flight-level wind of 62 kt, and believable SFMR winds of 
around 50 kt, which supports an initial intensity of 50 kt. 
Data from aircraft indicated that the minimum pressure is around
999 mb. 
 
Nana is moving westward or 275/16 kt. A strong deep-layer ridge to
the north of the tropical cyclone should steer it westward over the 
next day or so.  After that time, the ridge is forecast to build 
west-southwestward and the dynamical models indicate that this will 
cause Nana to turn west-southwestward by Thursday.  On this track,  
Nana is expected to approach the coast of Belize late Wednesday 
night or early Thursday, and move inland over Belize and Guatemala 
later that day.  The track guidance is in good agreement on this 
scenario but has trended slightly southward, which seems reasonable 
given that Nana is vertically deep and is more likely to feel the 
deep-layered east-northeasterly flow.  The new NHC track forecast is 
close to the FSU Superensemble and the HFIP corrected consensus 
model. 

The tropical storm is currently within an environment of light to 
moderate northeasterly shear.  This shear does not seem to be strong 
enough to prevent strengthening during the next 12-24 hours, and 
the NHC intensity forecast shows a slightly faster rate of 
intensification during that time.  This is in agreement with the 
latest SHIPS model output and the HCCA and HWRF models, and calls 
for Nana to become a hurricane within 24 hours.  The shear is 
forecast to become more northerly just before landfall, and this 
is likely to slow the intensification process.  Rapid weakening is 
expected after landfall, and the low-level circulation is expected 
to dissipate over Guatemala or southeastern Mexico by day 3.

KEY MESSAGES:
 
1. Tropical Storm Nana is 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  02/0300Z 17.0N  80.9W   50 KT  60 MPH
 12H  02/1200Z 17.1N  83.5W   60 KT  70 MPH
 24H  03/0000Z 17.0N  86.3W   65 KT  75 MPH
 36H  03/1200Z 16.8N  88.6W   65 KT  75 MPH...INLAND
 48H  04/0000Z 16.5N  90.7W   35 KT  40 MPH...INLAND
 60H  04/1200Z 16.2N  93.1W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  05/0000Z...DISSIPATED
 
$$
Forecaster Brown
 
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