[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT41 KNHC 152037
TCDAT1

Hurricane Iota Discussion Number  10
NWS National Hurricane Center Miami FL       AL312020
400 PM EST Sun Nov 15 2020

The satellite presentation of Iota has continued to improve this
afternoon.  A ragged eye has become apparent in visible satellite
imagery, with excellent banding features surrounding it.  An Air
Force Reserve Hurricane Hunter aircraft measured a minimum central
pressure of 977 mb during its first pass through the center earlier
this afternoon, and recorded around 974 mb on its second pass.
Somewhat surprisingly, the plane only measured peak 700-mb
flight-level winds of 74 kt and SFMR winds of 68 kt.  Those winds
support an intensity slightly lower than what was previously
estimated, but given the low central pressure and downward trend,
plus the fact that the plane only made a single pass in each
quadrant, it is possible that the maximum winds were not sampled.
In addition, the satellite presentation and pressure fall may be
preceding the winds slightly.  Therefore, the initial is again set
at 80 kt.  Another Air Force Reserve reconnaissance aircraft is en
route and should provide additional information on Iota's intensity
this evening.

Very favorable atmospheric and oceanic conditions consisting
of low vertical wind shear and warm waters are expected to lead to
rapid strengthening until the center crosses the coast of Central
America.  The NHC intensity forecast again calls for Iota to reach
major hurricane strength tonight, and become an extremely dangerous
category 4 hurricane before it reaches the coast of Central America
Monday night.  The NHC intensity forecast is similar to the
previous advisory and shows a peak slightly above the latest HFIP
corrected consensus model.  After landfall, rapid weakening should
occur as Iota moves over the mountainous terrain of Central America.

Iota is moving westward to west-northwestward at about 8 kt. The
track forecast philosophy is unchanged from before.  A strong
mid-level ridge that extends across the western Atlantic and
Florida will steer Iota westward to west-northwestward through
landfall Monday night. Once Iota moves over Central America, a
westward to west-southwestward motion is expected. The updated
NHC track forecast has been adjusted southward through 24 hours,
but little overall change was required thereafter. The official
forecast lies near the middle of the tightly clustered dynamical
model envelope.

In addition to potentially catastrophic winds, Iota is expected to
bring a life-threatening storm surge and extreme rainfall impacts
to portions of Central America. This comes less than two weeks
after Hurricane Eta significantly impacted the area.


Key Messages:

1. Iota is expected to continue to rapidly intensify and be an
extremely dangerous category 4 hurricane when it approaches the
coast of Central America on Monday.  Potentially catastrophic
winds and a life-threatening storm surge are expected along portions
of the coast of northeastern Nicaragua and eastern Honduras where a
hurricane warning is in effect.

2.  Hurricane conditions are expected and storm surge impacts
are possible on Providencia tonight and Monday.  Tropical storm
conditions are expected and hurricane conditions are possible on
San Andres.

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


FORECAST POSITIONS AND MAX WINDS

INIT  15/2100Z 13.3N  79.3W   80 KT  90 MPH
 12H  16/0600Z 13.6N  80.5W  100 KT 115 MPH
 24H  16/1800Z 14.0N  82.1W  120 KT 140 MPH
 36H  17/0600Z 14.3N  83.6W  105 KT 120 MPH...INLAND
 48H  17/1800Z 14.4N  84.9W   60 KT  70 MPH...INLAND
 60H  18/0600Z 14.3N  86.3W   35 KT  40 MPH...INLAND
 72H  18/1800Z 14.1N  87.9W   25 KT  30 MPH...INLAND
 96H  19/1800Z...DISSIPATED

$$
Forecaster Brown

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