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Tropical Storm THETA

Tropical Storm Theta Discussion Number  17
NWS National Hurricane Center Miami FL       AL302020
300 AM GMT Sat Nov 14 2020

Theta is beginning to show signs of weakening tonight. Infrared 
cloud top temperatures have warmed during the past several hours 
within the weakening convective band that curves around the 
northeastern semicircle of the storm. A partial 22 UTC ASCAT-B 
overpass indicates that Theta maintains a fairly symmetric low-level 
wind field, with 35-40 kt winds in the eastern semicircle of the 
storm. Therefore, the initial intensity is lowered to 45 kt with 
this advisory, which is consistent with UW-CIMSS objective current 
intensity estimates but slightly higher than the T2.5 subjective 
Dvorak classification from TAFB.

Theta will encounter increasingly hostile environmental conditions 
over the next couple of days. The NHC intensity forecast calls for 
steady weakening through the weekend, as strong northerly wind shear 
and cool sea surface temperatures will likely inhibit the storm from 
sustaining convection near its center. This forecast closely follows 
the corrected consensus aid HCCA. Theta is expected to weaken to a 
tropical depression within 36 h and degenerate into a remnant low by 
48 h, although the GFS simulated satellite imagery suggests this 
could occur even sooner than forecast. The remnant low should 
dissipate by the middle of next week.
Theta is still moving eastward at around 9 kt around the northern 
periphery of a mid-level ridge that extends from western Africa 
across the eastern tropical Atlantic. An eastward or 
east-southeastward motion with a gradual decrease in forward speed 
is expected during the next 24-36 h. As the storm spins down and 
becomes a more shallow circulation, the remains of Theta will turn 
northward and then accelerate northeastward ahead of a mid-latitude 
cyclone and associated frontal system that will cross the 
northeastern Atlantic. The NHC track forecast lies close to the 
previous one and near the center of the guidance envelope. On the 
forecast track, the center of Theta is expected to pass northwest of 
the Canary Islands this weekend, then move near Madeira Island early 
Monday as a weak remnant low.
INIT  14/0300Z 31.9N  21.6W   45 KT  50 MPH
 12H  14/1200Z 31.8N  20.2W   40 KT  45 MPH
 24H  15/0000Z 31.6N  18.6W   35 KT  40 MPH
 36H  15/1200Z 31.7N  17.8W   30 KT  35 MPH
 48H  16/0000Z 32.3N  17.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 60H  16/1200Z 33.7N  17.3W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  17/0000Z 35.9N  16.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  18/0000Z...DISSIPATED
Forecaster Reinhart/Cangialosi