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Hurricane Tammy Discussion Number  29
NWS National Hurricane Center Miami FL       AL202023
1100 AM AST Wed Oct 25 2023

Tammy has improved its satellite presentation this morning. Since 
the previous advisory, the hurricane briefly had a symmetric eye in 
the satellite infrared and microwave imagery. A nearby deep-layer 
trough appears to be limiting the western portion of Tammy's 
outflow. The subjective and objective intensity estimates have 
increased to 89 to 92 kt, and therefore the initial intensity has 
been raised to 90 kt. 

The upper-level environmental conditions are expected to be 
conducive for the next few hours with enhanced 200 mb divergence 
associated with the aforementioned trough. After 12 hours, the 
divergence is expected to decrease and strong shear, cooling SSTs, 
and surrounding dry subsident air should gradually weaken the 
hurricane. Model guidance suggests Tammy will undergo extratropical 
transition by Thursday and as a result, the tropical-storm-force 
wind field is expected to expand. The official intensity forecast is 
similar to the previous advisory and follows the various consensus 
aids.

Tammy is moving northeastward at about 11 kt, within the flow 
between a deep-layer trough over the western Atlantic and a 
subtropical ridge over the central Atlantic. Later today, the 
cyclone is expected to turn northward followed by a 
north-northwestward to northwestward turn on Thursday with a slower 
forward speed. By Friday, Tammy is expected to meander over the 
northwestern Atlantic in the light steering currents between two 
building ridges over the eastern Atlantic and southeastern United 
States. The 3- to 5-day steering flow forecast is rather uncertain 
and as a result there is a large spread in the track model guidance 
after 48 hours. The latest NHC track forecast is east of the 
previous prediction and favors the left side of the guidance 
envelope. 

 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  25/1500Z 26.6N  59.3W   90 KT 105 MPH
 12H  26/0000Z 28.2N  58.8W   85 KT 100 MPH
 24H  26/1200Z 29.8N  59.5W   75 KT  85 MPH...POST-TROP/EXTRATROP
 36H  27/0000Z 30.5N  60.7W   65 KT  75 MPH...POST-TROP/EXTRATROP
 48H  27/1200Z 31.0N  61.8W   60 KT  70 MPH...POST-TROP/EXTRATROP
 60H  28/0000Z 31.2N  62.2W   55 KT  65 MPH...POST-TROP/EXTRATROP
 72H  28/1200Z 31.4N  62.7W   50 KT  60 MPH...POST-TROP/EXTRATROP
 96H  29/1200Z 31.7N  63.0W   45 KT  50 MPH...POST-TROP/EXTRATROP
120H  30/1200Z 31.9N  63.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
 
$$
Forecaster Bucci/R. Zelinsky
 
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