[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 180553
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 UTC Sat Sep 18 2021

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 31N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 0000 UTC surface analysis and satellite imagery through
0530 UTC.

...SPECIAL FEATURES...

Tropical Storm Odette is centered near 36.4N 71.2W at 18/0300 UTC
or 230 nm SE of Cape May New Jersey and moving NE at 9 kt.
Estimated minimum central pressure is 1010 mb. Maximum sustained
wind speed is 35 kt with gusts to 45 kt. Seas are peaking at 12 to
13 ft near and up to 90 nm in a semicircle N of the center.
Numerous moderate to isolated strong convection is noted well NE
of the center from 36N to 40N between 65W and 69W. Odette is
expected to continue a NE track with little change in speed
through Sunday. This will take Odette S of the Northeast U.S. and
Atlantic Canada coasts over the weekend. Odette is forecast to
maintain its current intensity while transitioning into an extra-
tropical storm through Saturday night. Afterward, gradual
strengthening is likely and Odette will become a strong
extratropical storm on Sunday. Please read the latest NHC Public
Advisory at https://www.nhc.noaa.gov/text/MIATCPAT5.shtml for more
information. The Atlantic Offshore Waters Forecast issued by OPC
can be found at
https://www.ocean.weather.gov/offshore/indexphp?basin=atl&type=offshore#close

Showers and thunderstorms are gradually becoming better organized
in association with an area of low pressure and tropical wave
located about 1100 miles ESE of the northern Leeward Islands.
Fresh trades and seas of 6 to 8 ft are found from E to NE to NNW
of this system from 13N to 21N between 43W and 49W. Environmental
conditions are expected to be conducive for further development
during the next couple of days, and a tropical depression is
likely to form during the next day or two while the system moves
toward the WNW at about 15 mph. This system is expected to be near
the northern Leeward Islands on Monday and Tuesday, and interests
there should monitor the progress of this disturbance. The system
has a high chance of formation within the next 48 hours. Refer to
the latest NHC Tropical Weather Outlook at www.hurricanes.gov for
more details.

...TROPICAL WAVES...

An Atlantic tropical wave is along 23W from 19N southward through
the Cabo Verde Islands and a broad 1010 mb low pressure near
09N25W, and moving W near 15 kt. Scattered moderate to isolated
strong convection is found from 04N to 10N between 21W and 30W.
Scattered moderate convection is seen near the Cabo Verde Islands
from 11N to 16N between 20W and 28W. The system has a low chance
of formation within the next 48 hours. Refer to the latest NHC
Tropical Weather Outlook at www.hurricanes.gov for more details.

Another Atlantic tropical wave is near 50W from 19N southward
through a 1011 mb low pressure, and moving W near 15 kt. Scattered
moderate to isolated strong convection is present from 13N to 18N
between 44W and 52W. See the Special Features section above for
potential development of this system.

A W Caribbean tropical wave is along 85W from 18N southward across
Honduras, Nicaragua and Costa Rica to the E Pacific Ocean, and
moving W near 10 kt. Scattered showers and isolated thunderstorms
are occurring over these nations and adjacent waters.

...MONSOON TROUGH/ITCZ...

A monsoon trough extends across the African coast near the
Mauritania-Senegal border at 17N16W through the 1010 mb low
mentioned in the Tropical Waves section above to 11N38W. No ITCZ
is present based on the latest analysis. Scattered moderate
convection is evident near the Mauritania and Senegal coast from
15N to 21N.

The E end of the E Pacific monsoon trough is triggering scattered
showers and thunderstorms near the Panama-Colombia border.

...GULF OF MEXICO...

A surface trough reaches northeastward from the N Bay of Campeche
to the N central Gulf. Aided by divergent winds aloft, scattered
heavy showers and thunderstorms are present over the central and E
Gulf, including the W coast of central Florida. Locally moderate
to fresh winds and seas at 4 to 5 ft are possible near these
showers and thunderstorms. Otherwise, light to gentle winds and
seas at 1 to 3 ft prevail across much of the Gulf.

For the forecast, weak high pressure will extend across the
E and central Gulf through early next week. This pattern will
support continued gentle winds and mostly slight seas across the
Gulf through the next several days. Looking ahead, a weak cold
front may move into the NW and N central Gulf by mid week.

...CARIBBEAN SEA...

Convergent trade winds are producing scattered showers and
isolated thunderstorms over SE Cuba and S Hispaniola, and
adjacent waters. Refer to the Tropical Waves section above for
additional convection in the Caribbean Basin.

Tightening gradient between the Atlantic ridge to the north, and
E Pacific monsoon trough near Panama and N Colombia is generating
fresh to strong NE to ENE trades and seas at 6 to 8 ft over the S
central basin. Gentle trades and seas of 2 to 4 ft are present
across the E basin. Gentle to moderate trades and seas at 3 to 5
ft prevail across the remainder of the basin, including the
Yucatan Channel.

For the forecast, the Atlantic ridge will shift westward through
Sun, as Tropical Storm Odette, off the middle Atlantic coast,
lifts northward. This will support fresh to strong winds over the
S central Caribbean and Gulf of Honduras into early Sun. The
ridge will weaken starting Sun night as a tropical wave and area
of low pressure currently across the central Atlantic move to the
northeast of the Leeward Islands early Mon, then begin to move
more NW. There is a high chance this low pressure will form into a
tropical cyclone over the next several days. Regardless of
further development, expect increase winds, seas and thunderstorms
N through E of the Leewards early next week.

...ATLANTIC OCEAN...

Please see the Special Features section above for potential
tropical development in the Atlantic Basin. The combination of a
mid to upper-level trough near 29N50W and a surface trough at
23N51W is triggering scattered moderate convection from 21N to 31N
between 46W and 53W. Locally fresh winds and seas up to 6 ft are
possible near this convection. Refer to the Tropical Waves and
Monsoon Trough/ITCZ sections for additional convection across the
basin.

An expansive surface ridge extends southwestward from a 1027 mb
Azores high across S of Bermuda to Florida. This feature is
providing gentle to moderate winds with seas at 3 to 4 ft N of 26N
between 36W and the Georgia-N Florida coast. Other than the fresh
winds and higher seas mentioned near the 1010 mb low in the
Special Features section, gentle to moderate winds and seas of 3
to 4 ft are seen N of between 10N and 26N between 50W and the S
Florida Coast and the Lesser Antilles. Moderate to locally fresh
NE trades and seas at 6 to 8 ft are evident N of 27N between the
African coast and 36W. Gentle to locally moderate winds and seas
of 4 to 6 ft prevail across the rest of the basin.

For the forecast west of 65W, weak ridging through the N Bahamas
will support mostly light breezes and slight seas north of 22N
through early next week, and moderate trade winds and moderate
seas south of 22N at least through Sun. Meanwhile, an area of low
pressure currently well to the SE over the central tropical
Atlantic will approach the waters NE of the Leeward Islands Sun
and Mon, then begin to move more NW over open Atlantic waters.
There is a high chance this low pressure will form into a tropical
cyclone over the next several days. Regardless of further
development, expect increase winds, seas and thunderstorms N
through E of the Leewards Islands and NE of Puerto Rico early
next week.

$$

Chan
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