Tropical Storm ETA (Text)

Tropical Storm Eta Discussion Number   6
NWS National Hurricane Center Miami FL       AL292020
1000 PM EST Sun Nov 01 2020
Eta has continued to become better organized this evening, including 
the development of an impressive Central Dense Overcast (CDO) with 
cloud tops colder than -90C near the center, improved banding 
features in the northwestern semicircle, and the formation of a 
pinhole mid-level eye noted in 01/2322Z 91GHz SSMI/S microwave 
imagery. Water vapor imagery also indicates that the upper-level 
outflow pattern has continued to expand, with dual outflow channels 
having formed to the northeast and the southwest. Satellite 
intensity estimates are a consensus T3.5/55 kt from TAFB, SAB, and 
UW-CIMSS ADT. However, the initial intensity is set a little higher 
at 60 kt based on the pinhole eye feature...and this intensity 
estimate is probably conservative. An Air Force Reserve hurricane 
hunter aircraft is scheduled to investigate Eta in a few hours.

Eta has slowed down but is still moving westward, or 270/11 kt. An 
expansive subtropical ridge that extends from the southwestern 
Atlantic across the Bahamas, Florida, and into the Gulf of Mexico is 
expected to keep Eta moving in a general westward direction through 
Monday morning. By Monday afternoon and evening, the portion of the 
ridge over the Gulf is forecast to build southward and eastward in 
the wake of an exiting mid-latitude trough currently moving across 
the eastern and southeastern United States. The increased ridging 
will act to force Eta west-southwestward and eventually 
southwestward over the next 36 hours, resulting in landfall along 
the northeastern coast of Nicaragua. After moving inland, steering 
currents are forecast to weaken significantly on days 3-5 as another 
trough digs southeastward out of the U.S. Plains and into the Gulf 
of Mexico, eroding the Gulf ridge and causing Eta to drift slowly 
westward across Central America. Compared to the preponderance of 
the the model guidance, the HWRF solution of Eta remaining just 
offshore over the northwestern Caribbean Sea is considered to be an 
outlier. The new NHC track forecast is very similar to the previous 
advisory track, and lies close to the simple-consensus models TVCA 
and GFEX, which are a little to the right of the corrected-consensus 
model, HCCA. Based on the new NHC track forecast, no changes are 
required to the existing tropical cyclone warnings and watches in 

Eta has rapidly intensified 20 kt during the past 12 h. Given the 
much improved inner-core structure as noted in the SSMI/S imagery, 
combined with sea-surface temperatures in excess of 29 deg C, 
mid-level humidity values greater than 80 percent, and the already 
impressive outflow pattern, Eta should continue to rapidly 
strengthen until landfall occurs. The main question is: how much 
strengthening will take place? Some of the more reliable intensity 
guidance brings the cyclone up to 105-110 kt in 36 hours, with the 
HWRF model bringing Eta to near category-4 strength. The new NHC 
intensity forecast shows Eta as a major hurricane in 36 hours when 
it is expected to be located just inland over northeastern 
Nicaragua, but a stronger intensity is highly probable just before 
landfall occurs. Rapid weakening is forecast thereafter while the 
cyclone moves over the rugged, mountainous terrain of Nicaragua and 
Honduras, with Eta possibly devolving into a large, quasi-stationary 
Central American Gyre (CAG).
Key Messages:
1. Eta is forecast to strengthen into a hurricane by early Monday 
morning. Additional strengthening is forecast thereafter, and Eta 
is expected to be a major hurricane before it reaches the 
northeastern coast of Nicaragua Monday night or early Tuesday, where 
a Hurricane Warning is in effect. A Tropical Storm Warning is in 
effect for a portion of the northeastern coast of Honduras.
2. Through Friday evening, heavy rainfall from Eta will lead to 
catastrophic, life-threatening flash flooding and river flooding 
across portions of Central America, along with landslides in areas 
of higher terrain.  Flash and river flooding is also possible across 
Jamaica, southeast Mexico, El Salvador, southern Haiti, and the 
Cayman Islands.
3. A life-threatening storm surge, along with damaging waves, is 
expected along portions of the northeastern coast of Nicaragua near 
and to the north of where the center makes landfall.  Water levels 
could reach as high as 10 to 15 feet above normal tide levels in 
some parts of the hurricane warning area. Preparations to protect 
life and property should be rushed to completion.
INIT  02/0300Z 14.9N  80.0W   60 KT  70 MPH
 12H  02/1200Z 14.8N  81.3W   75 KT  85 MPH
 24H  03/0000Z 14.5N  82.6W   90 KT 105 MPH
 36H  03/1200Z 14.1N  83.4W  100 KT 115 MPH...INLAND
 48H  04/0000Z 14.0N  84.2W   60 KT  70 MPH...INLAND
 60H  04/1200Z 14.0N  85.3W   45 KT  50 MPH...INLAND
 72H  05/0000Z 14.2N  86.5W   30 KT  35 MPH...INLAND
 96H  06/0000Z 14.9N  88.4W   25 KT  30 MPH...INLAND
120H  07/0000Z 15.7N  88.5W   25 KT  30 MPH...INLAND
Forecaster Stewart

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Page last modified: Thursday, 31-Dec-2020 12:10:44 UTC