[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT41 KNHC 141457
TCDAT1

Tropical Storm Iota Discussion Number   5
NWS National Hurricane Center Miami FL       AL312020
1000 AM EST Sat Nov 14 2020

Recent microwave satellite imagery and early morning visible
pictures show that Iota remains a sheared tropical cyclone, with
the center located near the southwestern edge of the main
convective mass.  The initial intensity is held at 35 kt and is
based on the earlier ASCAT data and recent satellite estimates. An
Air Force Reserve reconnaissance aircraft is scheduled to
investigate Iota early this afternoon. Somewhat surprisingly Iota
has not strengthened much since yesterday, which appears to be the
result of some unexpected shear and its close proximity to the
northwest coast of Colombia. The global models predict that the
shear will relax soon, and that the system will be in quite
favorable conditions for strengthening.  The NHC forecast again
calls for steady to rapid strengthening in the next 12-60 h once
the storm organizes enough to take advantage of the expected
favorable conditions. The updated NHC intensity is similar to the
previous forecast and shows Iota at or near major hurricane
strength when it approaches the coast of Central America.

Although the center of Iota was relocated to the south and west of
the earlier estimates, the long-term initial motion estimate is
255/4 kt. The track forecast reasoning remains unchanged from the
previous advisory.  A mid-level ridge over the Gulf of Mexico
is expected to build eastward to the north of Iota during the
next day or two, and this feature should cause the cyclone to move
westward to west-northwestward at a faster forward speed during the
next few days. This should bring the center near the coast of
northeastern Nicaragua or Honduras in 2 to 3 days.  After landfall,
a west-southwestward motion is expected with Iota moving inland
over Central America.  The new NHC track forecast has been adjusted
southward, especially in the first 24 to 36 hours due to the more
southward initial position.  The NHC track lies close to the TVCA
multi-model consensus, which is between the lastest global model
interpolated trackers and the model fields.

Key Messages:

1. Iota is expected to strengthen and be at or near major
hurricane strength when it approaches the coast of Central America.
There is a risk of dangerous wind, storm surge, and rainfall
impacts across portions of Nicaragua and Honduras beginning Monday.
Hurricane Watches will likely be issued for a portion of this area
later today. Tropical Storm Warnings are in effect for the islands
of San Andres and Providencia.

2. Through Thursday, heavy rainfall from Iota will likely lead to
life-threatening flash flooding and river flooding across portions
of northern Colombia and Central America. Flooding and mudslides in
Honduras and Nicaragua could be exacerbated by Hurricane Eta’s
recent effects there, resulting in significant impacts.


FORECAST POSITIONS AND MAX WINDS

INIT  14/1500Z 12.7N  76.2W   35 KT  40 MPH
 12H  15/0000Z 12.9N  76.8W   45 KT  50 MPH
 24H  15/1200Z 13.4N  78.2W   55 KT  65 MPH
 36H  16/0000Z 13.9N  80.0W   70 KT  80 MPH
 48H  16/1200Z 14.2N  81.6W   85 KT 100 MPH
 60H  17/0000Z 14.4N  83.0W   95 KT 110 MPH
 72H  17/1200Z 14.5N  84.3W   75 KT  85 MPH...INLAND
 96H  18/1200Z 14.3N  86.7W   35 KT  40 MPH...INLAND
120H  19/1200Z 13.5N  90.0W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Brown

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