[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 181805 RRA
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 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 1200 UTC surface analysis and satellite imagery through
1745 UTC.

...SPECIAL FEATURES...

The remnant low of Iota is centered near 13.8N 89.5W at 18/1500
UTC or 17 nm WNW of San Salvador, El Salvador moving W at 10 kt.
Estimated minimum central pressure is 1006 mb. Maximum sustained
wind speed is 25 kt with gusts to 35 kt. The remnants of Iota
are expected to produce additional rainfall accumulations through
Thursday. This rainfall will lead to significant,
life-threatening flash flooding and river flooding, along with
mudslides in areas of higher terrain. Please read the last 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
continue to build southward across the Gulf of Mexico behind a
stationary front that extends from the Straits of Florida to the
N-central Yucatan Peninsula. The high pressure will continue to
create a very tight gradient between it and the front 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 the waters adjacent to the Yucatan Channel through
early Thursday, 19/1200 UTC. Expect building seas of 10-16 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 SE swell generated
by Iota which is propagating 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 are occurring in
the southeastern half of the Gulf of Mexico behind a stationary
front approaching the basin will spread into the far
northwestern Caribbean with gusts to gale force behind the front
and N of 20N from this morning through early Thursday. The 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 E-SE 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 behind the cold front which currently extends from 31N61W
to near 23N80W across the basin. These gusts will begin this
evening, 19/0000 UTC through Thursday evening, 20/0000 UTC
offshore the Bahamas from 22N to 27N and W of 61W. Expect seas to
build to 8-14 ft with the highest first in the gulf stream, then
to NE of the Bahamas by Thursday night. 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...

The axis of a low amplitude tropical wave is along 41W from
the equator to 14N, moving westward at 15-20 kt. Isolated
moderate convection is from 00N-10N between 34W-51W.

The axis of a tropical wave is along 62W from 18N southward
across the Lesser Antilles to near eastern Venezuela, moving
westward around 10 kt. Isolated moderate convection is from
06N-20N between 60W-65W, and from 20N-24N between 58W-64W.

The axis of a tropical wave is along 73W from Haiti
southward to N Colombia, moving westward at around 10 kt.
Isolated moderate convection is E of the tropical wave axis to
68W to include the ABC Islands.

...MONSOON TROUGH/ITCZ

The monsoon trough axis extends from the coast of Sierra Leone
near 08N12W to 07N15W. The ITCZ axis continues from 07N15W to
04N40W then resumes W of a tropical wave near 04N43W to the coast
of Brazil near 02N50W. Scattered moderate convection is along the
coast of Sierra Leone from 05N-09N between 11W-15W. Scattered
moderate convection is from 03N-07N between 21W-34W.

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.

The stationary front extends westward from the Straits of Florida
near 23N80W to the north Yucatan Peninsula to the Bay pf Campeche
near 19N94W. Scattered showers are within 60 nm of the front.

Strong winds, frequent gusts to gale force, and building seas can
be expected through tonight across the central Gulf and Straits
of Florida as high pressure builds north of the area behind a
front exiting the southern Gulf. In addition, southerly swell
from Iota, now well inland over Central America, is moving
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 Depression Iota and on a Gale Warning in effect for the
northwestern Caribbean north of 20N.

A quasi-stationary front is just NW of the basin and will drift
into the far NW Caribbean today. Ahead of this front, fresh to
strong NE winds are already occurring across the NW Caribbean
due to a tight pressure gradient between the remnant of Iota and
building high pressure N of the area. Mainly moderate trades
prevail elsewhere, locally fresh in the eastern Gulf. Seas are
8-13 ft in the NW Caribbean in mixed NE wind waves and remnant
E-SE swell generated by Iota. Seas of 3-6 ft prevail elsewhere
across the basin.

A 1011 mb low pressure area is noted in the SW Caribbean Sea near
12N81W. Environmental conditions are expected to be only
marginally conducive for slow development over the next several
days while the system moves slowly west-southwestward or
westward 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.
Please read the  latest Tropical Weather Outlook issued by the
National Hurricane Center at website
www.nhc.noaa.gov/text/MIATWOAT.shtml for more details.

ATLANTIC OCEAN...

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

SE of the cold front discussed above, a trough is analyzed from
31N59W to 26N65W. Scattered moderate convection is noted within
45 nm either side of the trough. Mainly moderate NE-E winds
prevail W of 65W along with seas of 4-6 ft. Another dissipating
cold front is over the eastern Atlantic near the Canary Islands,
extending from 31N15W to 26N28W. Scattered showers are noted
near the front. Associated seas of 7-10 ft have propagated S of
the front reaching to 20N. Moderate to fresh easterly winds are
noted across the waters E of 60W, with gentle to moderate winds
between 60W-65W. Seas are 5-8 ft across the remainder of the
basin in mixed swell.

The cold front in the SW N Atlantic will stall from near 26N65W
to near the Turks and Caicos Thu night, gradually weakening and
then drifting back NW as a remnant warm front through the end of
the week before dissipating by early Sat. A non-tropical area of
low pressure could form between the Bahamas and Bermuda by early
next week along the remnants of the front. The system could
gradually develop subtropical characteristics through the middle
of next week while it moves northeastward. Please read the
latest Tropical Weather Outlook issued by the National Hurricane
Center at website www.nhc.noaa.gov/text/MIATWOAT.shtml for more
details.

$$
Formosa
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