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Tropical Storm Gonzalo Discussion Number  12
NWS National Hurricane Center Miami FL       AL072020
1100 AM AST Fri Jul 24 2020
 
Gonzalo continues to produce bursts of deep convection, especially 
in the southeast quadrant, but has not become any better organized 
overall since the last advisory. Microwave imagery overnight 
indicated the low-level structure of Gonzalo is still largely 
intact, but this has not translated into better convective 
organization. ASCAT data valid shortly after 12Z revealed that 
Gonzalo has accelerated west faster than anticipated and has not 
strengthened. In fact the strongest winds in the ASCAT data were 
only 30-35 kt. The resolution of ASCAT likely limits its ability to 
sample the actual max winds of small storms like Gonzalo, but it is 
another indication that the cyclone has not strengthened and could
be weakening. The initial intensity for this advisory is set 
at 45 kt, based primarily on the latest TAFB Dvorak fix and the 
UW-CIMSS SATCON. An Air Force Reserve reconnaissance aircraft 
scheduled to investigate the storm this afternoon will provide a 
more information about Gonzalo's intensity and structure.

Due primarily to the adjusted initial position, the NHC track 
forecast has been adjusted a fair amount west and south of the 
previous advisory. Overall Gonzalo is still forecast to move 
generally westward or west-northwestward through the period, 
steered by the subtropical ridge to the north. The new NHC forecast 
lies between the old forecast, adjusted for the new initial 
position, and the HFIP Corrected Consensus.

The intensity guidance is generally lower than it has been for the
last day or so, and none of the operational models forecast Gonzalo
to reach hurricane strength. Unfortunately, small storms like 
Gonzalo are often subject to large swings in intensity, up or down, 
and that aspect of the forecast remains highly uncertain, even 
though the spread in the guidance is not particularly high. The NHC 
forecast has been adjusted only slightly lower for this cycle and 
is now above all of the guidance at the time the system is 
forecast to pass through the Windward Islands. A larger 
adjustment could be made later today if the most recent model 
trends continue, or if the recon mission finds that Gonzalo is even 
weaker than the current estimates.

 
Key Messages
 
1. Gonzalo is forecast to bring tropical storm conditions across 
portions of the southern Windward Islands Saturday and Saturday 
night. Hurricane and Tropical Storm Warning and Watches are 
currently in effect for some of the islands. Interests in the 
southern Windward Islands should monitor the progress of Gonzalo and 
follow any advice given by local officials.

2. Gonzalo is expected to produce heavy rain over portions of the 
southern Windward Islands. This could lead to life-threatening 
flash flooding.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  24/1500Z 10.0N  54.2W   45 KT  50 MPH
 12H  25/0000Z 10.5N  56.0W   50 KT  60 MPH
 24H  25/1200Z 11.4N  59.1W   55 KT  65 MPH
 36H  26/0000Z 12.4N  62.3W   60 KT  70 MPH
 48H  26/1200Z 13.0N  65.7W   50 KT  60 MPH
 60H  27/0000Z 13.7N  69.0W   40 KT  45 MPH
 72H  27/1200Z 14.0N  72.0W   30 KT  35 MPH
 96H  28/1200Z...DISSIPATED
 
$$
Forecaster Zelinsky
 
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