[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 012053
TCDAT4

Tropical Storm Eta Discussion Number   5
NWS National Hurricane Center Miami FL       AL292020
400 PM EST Sun Nov 01 2020

Eta has continued to quickly become better organized today with an
increase in banding and the development of a central dense overcast
feature.  A NOAA Hurricane Hunter aircraft that has provided a
couple of center fixes this afternoon has found a strengthening
tropical storm.  The aircraft has reported a minimum pressure of
992 mb and a 30 n-mi-wide eye that is open to the southwest.  A
blend of the SFMR and flight-level wind data support an initial wind
speed of 55 kt for this advisory.  Given the much improved
inner-core structure as reported by the reconnaissance aircraft and
the favorable environmental conditions of low vertical wind shear
and high ocean heat content, additional strengthening is likely.
The intensity guidance is much higher this cycle, and the various
rapid intensification models show a much more significant chance of
rapid strengthening over the next 24 to 36 hours.  The DTOPS model
indicates a 71 percent chance of a 30-kt increase in wind speed over
the next 24 hours, while the SHIPS Rapid Intensification Index shows
a 53 percent chance of a 45-kt increase over the next 36 hours.
Based on the higher initial intensity and the more bullish
guidance, the NHC intensity forecast has been increased and
essentially calls for rapid strengthening until Eta reaches the
coast of Central America.  Once inland, Eta should quickly weaken
over the mountainous terrain of Nicaragua and Honduras.

Eta is still moving steadily westward or 270 degrees at about 14
kt.  A westward motion at a somewhat slower forward speed is
expected tonight.  On Monday, Eta is forecast to turn southwestward
at a slower forward speed when a mid-level ridge builds to the
north and northwest of the cyclone.  Eta is forecast to move inland
over northeastern Nicaragua within the Hurricane Warning area
Monday night or early Tuesday. The dynamical models are in
relatively good agreement through about 72 hours, expect for the
HWRF which shows a more northern track and keeps Eta offshore for
much of the period.  This solution is considered an outlier at this
time, and the NHC track is in good agreement with the various
global models and the HFIP corrected consensus model.  Some model
solutions still suggest Eta or its remnants will re-emerge over the
northwestern Caribbean Sea at or beyond day 5.  The new NHC 5-day
position is still inland near the Gulf of Honduras close to the
various consensus aids, but large uncertainty exists in the
forecast at that time range due to the large spread in the track
guidance.

Key Messages:

1. Eta is forecast to strengthen into a hurricane tonight, and
additional strengthening is forecast 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 afternoon, heavy rainfall from Eta will lead to
significant, 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, 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.


FORECAST POSITIONS AND MAX WINDS

INIT  01/2100Z 14.9N  78.9W   55 KT  65 MPH
 12H  02/0600Z 15.0N  80.5W   65 KT  75 MPH
 24H  02/1800Z 14.7N  82.1W   80 KT  90 MPH
 36H  03/0600Z 14.2N  83.1W   95 KT 110 MPH
 48H  03/1800Z 14.0N  83.8W   75 KT  85 MPH...INLAND
 60H  04/0600Z 14.0N  84.7W   50 KT  60 MPH...INLAND
 72H  04/1800Z 14.1N  85.7W   35 KT  40 MPH...INLAND
 96H  05/1800Z 14.7N  88.0W   25 KT  30 MPH...INLAND
120H  06/1800Z 15.5N  88.5W   25 KT  30 MPH...INLAND

$$
Forecaster Brown
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