[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 171741
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 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 1200 UTC surface analysis and satellite imagery through
1715 UTC.

...SPECIAL FEATURES...

Hurricane Iota is centered near 13.7N 85.2W at 17/1500 UTC or 117
nm E of Tegucigalpa Honduras moving W at 10 kt. Estimated minimum
central pressure is 980 mb. Maximum sustained wind speed is 65
kt with gusts to 80 kt. Scattered moderate to strong convection
is from 10N-19N between 78W-89W. Iota will move farther inland
across northern Nicaragua today, and move across southern
Honduras tonight before dissipating near El Salvador early
Wednesday. Iota should weaken to a tropical storm this afternoon,
a tropical depression this evening, and degenerate into a remnant
low pressure area on Wednesday. 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 near Fort Myers, Florida to the southern Bay
of Campeche. The high pressure will create a very tight gradient
between it and the front by this evening. 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 starting this evening, 18/0000 UTC through
Thu. Expect building seas 12 to 16 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 SE
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 NW Caribbean with gusts to gale force possible behind the
cold front and N of 20N Wed and Wed night. The cold front will
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 today through Wed night as fresh
northerly wind waves behind the front mix with swells 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 NW 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
Thu offshore of the Bahamas, and through Thu night from 22N-27N
and E of 70W. Expect seas to build 8 to 11 ft, except up to 14
ft
across the gulfstream approach to the Straits of Florida where
conditions will be very hazardous. 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 tropical wave is near 33W from the equator to 14N,
moving westward at 10-15 kt. Isolated moderate convection is
noted from 00N-09N between 30W-37W.

The axis of a tropical wave is near 57W from western Suriname
to 19N, moving westward at 10-15 kt. Isolated moderate
convection is noted within 240 nm of the wave axis.

The axis of a tropical wave is near 69W from near the Mona
Passage to western Venezuela, moving westward at 5-10 kt.
Scattered moderate to strong convection is noted from
04N-13N between 66W-71W to include the ABC Islands.

...MONSOON TROUGH/ITCZ

The monsoon trough axis extends from the coast of Africa near the
border of Guinea and Sierra Leone to 08N18W. The ITCZ axis
continues from 08N18W to 06N32W then continues west of a tropical
wave near 06N35W to the coast of Brazil near 00N51W. Scattered
moderate convection is along the ITCZ from 01N-07N between
20W-30W. Scattered moderate to isolated strong convection is from
02N-09N between 38W-53W.

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.

Ahead of the cold front mentioned above, scatterometer data
shows mainly moderate NE-E flow. SE swell associated with
Hurricane Iota, situated well SE-S of the basin, is already
spreading through the Yucatan Channel.

Conditions should improve across the basin by the end of the week
into the weekend. Moderate to fresh E-SE flow will prevail by Sat
night as the high pressure area that is building in behind the
cold front shifts E-NE 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
Hurricane Iota and on a Gale Warning in effect over the NW
Caribbean N of 20N.

Outside the influence of Hurricane Iota, isolated to scattered
moderate convection is moving across the northern islands of the
Lesser Antilles. Showers are also noted across the rest of the
Lesser Antilles. Moderate to locally fresh trade winds are noted
in the central and eastern Caribbean. Seas range 3-6 ft outside
the influence of Iota.

A new area of low pressure could form in a couple of days over
the central or southwestern Caribbean Sea. Environmental
conditions are forecast to be conducive for some development,
and a tropical depression could form by the end of the week while
the system moves slowly westward or west-southwestward across
the
southwestern Caribbean Sea. Otherwise, moderate to locally fresh
trades will prevail SE of the front in the NW Caribbean through
the end of the week into the weekend. Conditions in the NW
Caribbean will greatly improve this weekend as the front washes
out.

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 with the Gale Warning, another
cold front is noted, this one in the central Atlantic from 32N28W
to 27N42W to 30N53W. Scattered showers are within 60 nm of the
front. Moderate to fresh NE winds are noted N of the front along
with building seas of 8 ft in northerly swell. Two troughs are
analyzed in the central Atlantic. The western trough is from
26N61W to 21N66W, and the eastern trough is from 21N39W to
16N44W. Showers are within 60 nm of these troughs. Moderate to
fresh trades are noted across the waters E of 60W with seas of 5-
8 ft in mixed swell.

Other than the front and associated Gale Warning in the SW N
Atlantic, no other significant features are expected across the
basin through the next several days.

$$
Formosa
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