[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT41 KNHC 140839
TCDAT1

Tropical Storm Iota Discussion Number   4
NWS National Hurricane Center Miami FL       AL312020
400 AM EST Sat Nov 14 2020

Satellite imagery and scatterometer data received since the last
advisory indicate that Iota is a bit disorganized.  The deep
convection is currently not concentrated near the center, and the
scatterometer wind data showed an elongated circulation with a
trough extending west-southwestward from the center.  The
scatterometer data also showed maximum winds of 30-35 kt in the
northeastern quadrant, and based on this, the initial intensity is
held at 35 kt.  An Air Force Reserve Hurricane Hunter aircraft is
scheduled to investigate Iota at around 18Z.

Iota continues to move south of west with the initial motion of
245/4 kt.  A mid-level ridge over the Gulf of Mexico should build
eastward to the north of Iota during the next day or two, and this
feature should cause the cyclone to move westward at a somewhat
faster forward speed through 72 h.  This motion is expected to
bring the center near or over the coasts of Nicaragua or Honduras
near the  72-h point.  After that time, a west-southwestward motion
is forecast, with the center of the cyclone moving across portions
of Central America.  The new forecast track is similar to, but
slightly slower than, the previous forecast, and it lies in the
center of the guidance envelope near the various consensus models.

Iota is currently experiencing light westerly wind shear produced by
an upper-level trough to the west.  The shear should subside over
the next 12-24 h as the trough moves westward and dissipates,
leaving the cyclone in more favorable upper-level winds and over sea
surface temperatures near 29C.  Thus, conditions appear conducive
for steady to rapid intensification once the storm becomes well
enough organized internally to take advantage of the favorable
environment.  The new intensity forecast is similar to the previous
one, and calls for rapid intensification to major hurricane
intensity, with a peak intensity of near 105 kt as the system makes
landfall in Central America.  It should be noted that the HWRF and
HMON forecast the center to go north of the official forecast track
and keep it over water north of Honduras.  As a result, they
forecast a stronger cyclone than indciated by the official forecast.


Key Messages:

1. Iota is expected to strengthen and be a major hurricane 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.

2. Through Wednesday, 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  14/0900Z 13.5N  74.8W   35 KT  40 MPH
 12H  14/1800Z 13.6N  75.4W   45 KT  50 MPH
 24H  15/0600Z 13.9N  76.8W   55 KT  65 MPH
 36H  15/1800Z 14.3N  78.6W   70 KT  80 MPH
 48H  16/0600Z 14.5N  80.4W   85 KT 100 MPH
 60H  16/1800Z 14.8N  82.0W  100 KT 115 MPH
 72H  17/0600Z 14.9N  83.3W  105 KT 120 MPH...INLAND
 96H  18/0600Z 14.5N  86.0W   50 KT  60 MPH...INLAND
120H  19/0600Z 14.0N  89.0W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Beven

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