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Tropical Storm Julio Discussion Number   4
NWS National Hurricane Center Miami FL       EP152020
900 AM MDT Sun Sep 06 2020
 
Julio has surprisingly accelerated west-northwestward during the
past few hours, moving around the northeast periphery of a broad
trough of low pressure. The tiny tropical storm continues to
produce small but frequent bursts of central convection and has not
changed appreciably since the most recent ASCAT pass that supported
an intensity of 40 kt.
 
Julio's future is unusually unclear for a system that is forecast to
dissipate. The global models are struggling to resolve Julio, and
only the ECMWF has a realistic current depiction of the cyclone.
Those models universally indicate that Julio will either dissipate
or be absorbed by the aforementioned broad area of low pressure
located to its southwest within the next 24 to 36 hours. This is
certainly plausible given Julio's small size and limited convection.
On the other hand, the HWRF and HMON models now indicate that Julio
will not only persist through day 5, but potentially strengthen when
upper-level winds are forecast to become less hostile in a couple
days. The disagreement can not be explained entirely by model
resolution as the COAMPS-TC also weakens Julio.
 
I see no clear reason to support one solution over another at this 
point. Therefore, the official forecast continues to show 
dissipation for now, though the intensity has been hedged slightly 
higher at 48 h and 60 h. The NHC track forecast leans heavily on the 
HWRF and HMON models and has been adjusted significantly faster for 
the first 24 h due to Julio's recent acceleration. Much larger 
changes may be required to the forecast later today or tonight if it 
becomes more likely that Julio will persist longer than currently 
indicated.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  06/1500Z 19.2N 108.8W   40 KT  45 MPH
 12H  07/0000Z 19.9N 111.1W   45 KT  50 MPH
 24H  07/1200Z 20.3N 113.6W   45 KT  50 MPH
 36H  08/0000Z 20.4N 115.1W   45 KT  50 MPH
 48H  08/1200Z 20.2N 115.9W   40 KT  45 MPH
 60H  09/0000Z 20.2N 116.8W   35 KT  40 MPH...POST-TROPICAL
 72H  09/1200Z...DISSIPATED
 
$$
Forecaster Zelinsky
 
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