[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 180455
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 UTC Wed Nov 18 2020

Tropical Weather Discussion for North America, Central America
Gulf of Mexico, Caribbean Sea, northern sections of South
America, and Atlantic Ocean to the African coast from the
Equator to 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 0000 UTC surface analysis and satellite imagery through
0430 UTC.

...SPECIAL FEATURES...

Tropical Storm Iota is centered near 13.7N 87.3W at 17/0300 UTC,
or about 20 nm SSW of Tegucigalpa, Honduras, moving westward at
10 kt. Estimated minimum central pressure is 1000 mb. Maximum
sustained wind speed is 35 kt with gusts to 45 kt. Scattered
moderate convection is mostly inland with some convection along
the Nicaraguan coast and in the NW Caribbean from 12N to 20N
between 81W to 90W. Iota will move westward to west-southwestward
tonight and Wednesday. On the forecast track, the center of Iota
should move across portions of southern Honduras and El Salvador
before the system dissipates on Wednesday. Additional rapid
weakening is forecast, and Iota should weaken to a tropical
depression tonight and degenerate into a remnant low pressure area
on Wednesday. Expect storm totals across Honduras, northern
Nicaragua, southeast and central Guatemala and southern Belize 10
to 20 inches of rainfall, with isolated maximum totals of 30
inches. Life-threatening flash flooding and river flooding is
expected through Thursday across portions of Central America due
to heavy rainfall from Iota. Flooding and mudslides across
Honduras, Nicaragua and Guatemala could be exacerbated by
saturated soils in place, resulting in significant to potentially
catastrophic impacts. Please read the latest NHC Public Advisory
at https://www.nhc.noaa.gov/text/MIATCPAT1.shtml and
Forecast/Advisory at https://www.nhc.noaa.gov/text/MIATCMAT1.
shtml for more details.

Gulf of Mexico Gale Warning: Strong autumn high pressure will
build southward across the Gulf of Mexico behind a cold front
that extends from the Florida Keys to the southern Bay of
Campeche. The high pressure will create a very tight gradient
between it and the front beginning tonight. This is leading to
strong northeast winds, with frequent gusts to gale force over the
southeastern half of the Gulf waters, including the Straits of
Florida and waters adjacent to the Yucatan Channel from now
through through Thursday morning, 19/1200 UTC. Expect building
seas of 10-15 ft across this area. Very hazardous conditions can
be expected between the wind waves against the flow of the Gulf
stream through the Straits of Florida, and due to a southeast
swell generated by Iota which will move through the Yucatan
Channel. Please read the latest NWS High Seas Forecast issued by
the National Hurricane Center at website
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more details.

Caribbean Gale Warning: The same conditions that will occur in
the southeastern half of the Gulf of Mexico will spread into the
far northwestern Caribbean with gusts to gale force possible
behind the cold front and north of 20N from Wednesday morning,
18/1200 UTC through Thursday morning, 19/1200 UTC. The cold front
is forecast to stall from eastern Cuba to the Gulf of Honduras
early Thu. Large and hazardous seas will build to 8 to 13 ft
through the Gulf of Honduras and the Yucatan Channel as fresh
northerly wind waves behind the front mix with swell generated by
Iota. The highest seas are expected in the Yucatan Channel. Please
read the latest NWS High Seas Forecast issued by the National
Hurricane Center at website
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more details.

Atlantic Gale Warning: The pressure gradient which will lead to
frequent gusts to gale force over the southeastern Gulf of Mexico
and far northwestern Caribbean Sea will also bring frequent gusts
to the western Atlantic off the coast of South Florida and the
Bahamas. These gusts will begin by Wednesday evening, 19/0000 UTC
through Thursday evening, 20/0000 UTC offshore the Bahamas from
22N to 27N and east of 70W. Expect seas to build to 8-14 ft.
Please read the latest NWS High Seas Forecast issued by the
National Hurricane Center at website
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more details.

...TROPICAL WAVES...

An eastern Atlantic tropical wave has an axis along 37W from 13N
southward, moving westward at 10 kt. Scattered moderate
convection, in association with the ITCZ, is noted from 01N to
09N between 35W to 39W.

A central Atlantic tropical wave has an axis along 59W from 20N
southward to the northern coast of Guyana, moving westward at 10
kt. Isolated moderate convection is noted from 09N to 20N
between 58W to 61W.

A central Caribbean Sea tropical wave has an axis along 71W from
20N southward to the northern coast of Venezuela, moving
westward at 5-10 kt. Isolated convection is noted along the
southern coast of Hispaniola near the wave axis in addition to
scattered moderate convection from 11N to 16N between 67W to
70W.

...MONSOON TROUGH/ITCZ

The monsoon trough extends off the coast of Guinea-Bissau near
12N16W to 11N17W. The ITCZ continues from 11N17W to 07N24W to
06N35W. The ITCZ continues west of a tropical wave near 06N38W
to the coast of Brazil near 02N51W. Scattered moderate convection
is noted south of the monsoon trough and ITCZ from 02N to 06N
between 12W to 27W. Scattered moderate to isolated strong
convection is noted along the ITCZ from 02N to 07N between 31W to
51W.

GULF OF MEXICO...

See Special Feature section above for details on a Gale Warning
in effect over the southeastern Gulf of Mexico.

The cold front extends westward from the Straits of Florida near
24N80W to 22N90W to the southern Mexican coast near 19N93W.
Showers are noted along the front. A trough extends in the
western Bay of Campeche from 22N96W to 18N94W. Fresh to strong
NNE winds are noted along and behind the cold front across the
southeastern and southwestern Gulf. Moderate to fresh NE winds
are noted in the northeastern Gulf and moderate to fresh easterly
winds in the northwestern Gulf. Seas range from 5-9 ft with
upwards of 11 ft north of the Yucatan.

Strong winds, frequent gusts to gale force, and building seas
can be expected through late Wed across the central Gulf and
Straits of Florida as high pressure builds north of the area
behind a front moving across the southern Gulf. In addition,
southerly swell from Iota, now inland over Nicaragua, will move
through the Yucatan Channel. Conditions should improve by the
end of the week into the weekend.

CARIBBEAN SEA...

Please see the Special Features section for information on
Tropical Storm Iota and on a Gale Warning in effect for the
northwestern Caribbean north of 20N. See the Tropical Waves
section for information on the tropical wave in the central
Caribbean.

Outside convection associated with Tropical Storm Iota and the
tropical wave, scattered moderate convection is noted near the
Lesser Antilles from 12N to 15N between 60W to 64W. The latest
scatterometer data depicts gentle to moderate trades throughout
the Gulf with fresh to strong ENE winds in the NW Caribbean in
addition to the Gulf of Honduras. Seas range 4-6 ft in the
eastern and central Caribbean with 8-10 ft in the NW Caribbean.
Seas up to 12 ft are noted in the Gulf of Honduras.

A cold front will move into the NW Caribbean late tonight and
stall from eastern Cuba to the northern Gulf of Honduras early
Thu. Strong northerly winds, with frequent gusts to gale force N
of 20N, and large seas are expected in the Gulf of Honduras
early Wed through Wed night. Hazardous seas will be possible
across the approach to the Yucatan Channel behind the front as
northerly wind waves mix with swell from Iota.

A broad area of low pressure could form in a day or so over the
southwestern Caribbean Sea.  Environmental conditions do not
appear to be as conducive for development as previously thought,
but slow development is possible over the next several days
while the system moves slowly westward or west-southwestward
across the southwestern Caribbean Sea. Regardless of tropical
cyclone formation, areas of heavy rain are possible during the
next several days from Nicaragua southward across Central America
and into Colombia. These rains could cause new flooding concerns,
especially across previously inundated areas. The chance of
formation is low in the next 48 hours and the next 5 days.

ATLANTIC OCEAN...

See the Special Features section for details on a Gale Warning in
effect over the SW N Atlantic.

A cold front extends across the western Atlantic from 31N65W to
the Straits of Florida near 24N80W . Strong NE winds are noted
off behind the front between South Florida and the Bahamas with
moderate to fresh N winds off the northeast Florida coast.
Otherwise, gentle to moderate N winds are behind the cold front
E of 76W. Light to gentle easterly winds are ahead of the front.
A trough is located north of Hispaniola from 28N64W to 21N79W
with isolated moderate convection within 60 nm of the trough.

In the central Atlantic, a cold front enters the waters near
31N24W to 27N38W. No convection is associated with this feature
at this time. A trough is also in the central Atlantic, analyzed
from 19N45W to 13N48W. No convection is associated with this
feature at this time.

Outside of the southwestern Atlantic, moderate to fresh easterly
winds are noted in the central and eastern Atlantic. Seas range
4-8 ft across the Atlantic with 8-10 ft near the cold front in
the central Atlantic.

The cold front will reach from 25N65W to central Cuba by Wed
night, then stall on Thu. The front will weaken and retreat W-NW
for the end of the week into the weekend. Fresh to strong NE-E
winds are expected across most the SW N Atlantic tonight through
Fri as the pressure gradient tightens in the wake of the front.
Frequent gusts to gale force are forecast from 22N-27N Wed night
through Thu night.

$$
AReinhart
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