[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 180000
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Tue Nov 17 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 1800 UTC surface analysis and satellite imagery through
2345 UTC.

...SPECIAL FEATURES...

Tropical Storm Iota is centered near 13.7N 86.2W at 17/21500 UTC
or 757 miles ESE of Tegucigalpa Honduras moving W at 10 kt.
Estimated minimum central pressure is 993 mb. Maximum sustained
wind speed is 50 kt with gusts to 60 kt. Satellite imagery
shows scattered moderate to isolated strong convection offshore
Honduras and Nicaragua from 13N to 18N between 79W-83W and from
16N to 20N west of 83W to the inland the coast of the Yucatan
Peninsula and Belize. Similar convection is also over the
interior of Honduras and most of the interior of Nicaragua.

The center of Iota will move farther inland into southern
Honduras tonight before dissipating near El Salvador early
on Wed. Expect over Honduras, northern Nicaragua, southeast and
central Guatemala and southern Belize 10 to 20 inches of
rainfall, with isolated maximum totals of 30 inches. This
rainfall will lead to significant, life-threatening flash
flooding and river flooding, along with mudslides in areas of
higher terrain. Please refer to statements issued by your
national meteorological service for more details on the rainfall
and flooding threats. 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 upper Florida Keys to the south-central
Gulf near 23N88W, where it becomes stationary to the central
Bay of Campeche. The high pressure will create a very tight
gradient between it and the front beginning tonight. This
synoptic set-up is forecast to lead 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 the period of tonight
through Wed night. Expect building seas of 10-15 ft across this
area with very hazardous conditions 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 Wed and Wed night. The
cold front is forecast to stall from eastern Cuba to the Gulf of
Honduras early Thu. Large and hazardous seas are expected in the
Gulf of Honduras and approach to the Yucatan Channel through Wed
night as fresh northerly wind waves behind the front mix with
swell generated by Iota. 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 Wed evening (19/0000 UTC)
through Thu night offshore the Bahamas from 22N to 27N and east
of 70W. Expect seas to build 8-12 ft with these winds. 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 its axis along 35W/36W
from 01N to 15N. It is moving westward at 10-15 kt. Scattered
showers and isolated thunderstorms are within 240 nm west of
the wave from 05N to 07N, and within 60 nm east of the wave
from 05N to 08N.

A central Atlantic tropical wave has its axis along 58W/59W
south of 20N to northeastern Guyana near 05N59W. It is moving
westward at 10-15 kt. Scattered showers and isolated thunderstorms
are within 180 nm either side of the wave from 07N to 20N.
Scattered moderate to isolated strong convection is inland
Guyana and eastern Venezuela from 04N to 08N between the wave
and 66W. Similar activity is over western Suriname.

An eastern Caribbean Sea tropical wave has its axis along 70W/71W
south of 19N to across the Gulf of Venezuela and to inland
Colombia near 06N71W. It is moving westward at about 5-10 kt.
Scattered moderate to strong convection is seen over northern
Venezuela from 08N to 11N between 66W-72W.

...MONSOON TROUGH/ITCZ

The monsoon trough axis extends from the coast of Africa over
Guinea near 12N16W to 09N21W, where latest scatterometer data
indicates that it transitions to the ITCZ axis to 06N30W and
to just east of a tropical wave near 06N35W. It resumes west of
the tropical wave near 05N38W to the coast of Brazil near
00N51W. Scattered moderate to isolated strong convection is
within 240 nm north of the ITCZ between 40W-45W and within
120 nm south of the ITCZ between 40W-45W. Scattered moderate
convection is within 30 nm s of the ITCZ between 28W-34W.l

GULF OF MEXICO...

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

Latest scatterometer data shows a quite extensive area of
fresh to strong northeast winds covering the eastern and
central Gulf, while moderate to fresh northeast to east winds
are over the western Gulf. Southeast swell left behind from
Tropical Storm Iota will continue to propagate through the
Yucatan Channel through the next couple of days.

Conditions should improve across the basin by the end of the week
into the weekend. Moderate to fresh east to southeast winds
will prevail by Sat night as the high pressure area that is
building in behind the cold front shifts east-northeast to over
the Carolinas. Seas will have subsided to 4-7 ft across the basin
by Sat night as well.

CARIBBEAN SEA...

Please see the Special Features section for information on
Tropical Storm Iota now inland far northern Nicaragua and on a
Gale Warning in effect for the northwestern Caribbean north of
20N.

Outside convection associated to Tropical Storm Iota, scattered
showers and isolated thunderstorms that are being aided by
an upper-level low just east of the Leeward Islands near 17N60W,
are observed moving westward across the northern islands of the
Lesser Antilles. Showers are also noted across some of the Lesser
Antilles. Moderate to locally fresh trades are present over the
central and eastern Caribbean. Seas range 3-6 ft outside of those
tied to Iota.

Tropical Storm Iota is inland over Nicaragua and Honduras near
13.7N 86.2W 993 mb at 4 PM EST moving W at 10 kt. Maximum
sustained winds 50 kt gusts 60 kt. Iota will weaken to a remnant
low near 13.6N 87.8W Wed morning, and dissipate Wed afternoon. 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 gusts to gale force north 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

ATLANTIC OCEAN...

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

A cold front extends from just west of Bermuda southwestward to
28N74W and to the upper Florida Keys. Another cold well to the
southeast of this one is analyzed across the eastern and central
Atlantic from near 32N25W to 27N36W to 26N45W and northwest to
near 30N52W. Scattered showers are possible within 90 nm north of
the front east of 36W. Strong high pressure, anchored by a 1029
mb high center well north of the area near 37N38W, is north of
this front. This high pressure area is building across the front.
Moderate to fresh northeast winds are north of the front along
with building seas of 8 ft in northerly swell. Two troughs are
analyzed in the central Atlantic. The western trough extends from
26N64W to 21N69W, and the eastern trough extends from 21N41W to
15N47W. Scattered showers and isolated thunderstorms are within
120 nm west of the first trough from 22N to 23N, while isolated
showers are possible near the second trough from 16N to 20N
between 43W-47W. Moderate to fresh trades are noted across the
waters east of 60W with seas generally in the range of 5-8 ft in
mixed swell.

The western Atlantic cold front will reach from near 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 Tue night through Fri as the pressure gradient tightens
in the wake of the front. Frequent gusts to gale force are
possible from 22N-27N Wed night through Thu night. Otherwise,
no other significant features are expected across the basin
through the next several days.

$$
Aguirre
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