Tropical Storm ETA (Text)

Tropical Storm Eta Discussion Number  34
NWS National Hurricane Center Miami FL       AL292020
400 PM EST Sun Nov 08 2020
Eta's appearance in radar and satellite imagery has changed little 
since the previous advisory and the last reconnaissance mission a 
few hours ago, with a ragged mid-level eye-like feature briefly 
wrapping up for less than an hour before quickly decaying. Average 
velocity values from the Miami, Florida, NOAA WSR-88D Doppler 
weather radar have occasionally been as high as 60 kt between 
10,000-12,000 ft ASL to the north and northeast of the center. 
Therefore, the initial intensity is being maintained at 55 kt for 
this advisory. A NOAA reconnaissance aircraft is scheduled to 
investigate Eta around 0000Z this evening.
The initial motion estimate is 325/12 kt. There is no significant 
change to the previous track forecast reasoning from the last 36 
hours. Eta is now moving northwestward around the northeastern side 
of an upper-level low that has formed over the extreme northwestern 
Caribbean Sea near the Isle of Youth. The combined easterly flow 
between the upper-low and a deep-layer ridge located near the U.S. 
mid-Atlantic coast is expected to force Eta westward overnight and 
then turn the cyclone slowly southwestward in the 24-48 hour period, 
with the cyclone possibly stalling just west of the lower Florida 
Keys when steering currents collapse around 48 hours. By 72 hours 
and beyond, a broad mid-latitude trough is forecast to move from the 
U.S. west coast eastward over the central U.S. by 96 hours, and then 
over the eastern U.S. by 120 hours, which will erode the western 
portion of the ridge and act to gradually lift Eta northeastward 
toward northern Florida. The latest NHC model guidance has shifted 
slightly northward, possibly due to the NOAA G-IV jet aircraft 
synoptic track dropsonde observations from earlier this morning, and 
now shows the center of Eta making landfall in the middle or lower 
Florida Keys late tonight and early Monday. The new NHC official 
track forecast has been nudged northward close to the consensus 
models HCCA and TCVA. It should be noted that although the latest 
model guidance and track forecast shows landfall in the Florida 
Keys, the strongest winds are occurring, and are expected to occur, 
well to the north and east of the center.

Satellite imagery indicates that a pronounced dry slot has wrapped 
into the eastern portion of Eta's circulation, with radar data 
suggesting that it has occasionally penetrated into the inner core 
region as well, eroding the thunderstorm activity in the southern 
portion of the aforementioned eye-like feature. However, with the 
vertical shear forecast to steadily decrease from the current 25 kt 
down to less than 10 kt by 24 hours while Eta is moving over 28.5 
deg C SSTs, strengthening is expected late tonight during the 
convective maximum period and continuing into Monday, resulting in 
Eta intensifying into a hurricane during that time. Environmental 
conditions are expected to remain somewhat favorable for Eta to 
maintain hurricane status through 60 hours, followed by gradual 
weakening from 72-120 hours due to increasing southwesterly shear of 
20-25 kt and entrainment of very dry mid-level air. The latest 
official intensity forecast is similar to the previous NHC advisory, 
and remains above the model guidance through 36 hours and is a 
little below the guidance thereafter. 

Based on ASCAT data and surface observations, the wind radii were 
expanded in the northwest and northeast quadrants.
Key Messages:
1. Hurricane conditions are expected tonight and early Monday across 
portions of the Florida Keys, and are possible across portions of 
southern Florida. Tropical storm conditions will extend well away 
from Eta's center across the southern and central portions of the 
Florida peninsula.

2. There is a danger of life-threatening storm surge in portions of 
the Florida Keys.  Life-threatening storm surge is possible along 
portions of the southern coast of the Florida peninsula. Residents 
in these areas should follow any advice given by local officials.

3. Heavy rainfall from Eta will continue across portions of Cuba, 
Jamaica, the Bahamas, and southern Florida and will spread north 
into central Florida. This rain may result in significant, life- 
threatening flash flooding and river flooding in Cuba. Significant 
flash and urban flooding are also possible for Jamaica, the Bahamas 
and southern Florida, along with potential minor river flooding in 
central Florida.
INIT  08/2100Z 23.9N  79.5W   55 KT  65 MPH
 12H  09/0600Z 24.7N  81.1W   60 KT  70 MPH
 24H  09/1800Z 24.6N  83.4W   65 KT  75 MPH
 36H  10/0600Z 23.6N  84.8W   65 KT  75 MPH
 48H  10/1800Z 24.0N  85.1W   65 KT  75 MPH
 60H  11/0600Z 25.1N  85.0W   65 KT  75 MPH
 72H  11/1800Z 25.8N  84.8W   60 KT  70 MPH
 96H  12/1800Z 27.1N  84.0W   55 KT  65 MPH
120H  13/1800Z 29.0N  82.8W   50 KT  60 MPH
Forecaster Stewart

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Page last modified: Thursday, 31-Dec-2020 12:10:45 UTC