[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 270606
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 UTC Wed Sep 27 2023

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
0500 UTC.

...SPECIAL FEATURES...

Tropical Storm Philippe is centered near 17.4N 52.0W at 28/0300
UTC, or 635 nm E of the Northern Leeward Islands, and moving W at
10 kt. Estimated minimum central pressure is 1003 mb. Maximum
sustained winds are 40 kt with gusts to 50 kt. Peak seas are
20 to 21 ft near and just northeast of the center. Scattered to
numerous moderate convection with isolated strong convection is
seen near, and to the north and southeast of the center from 13N
to 20N between 46W and 52W. Philippe continues to struggle due to
strong southwesterly shear associated with an upper-level trough
to its north. A westward to west-northwestward motion and a
gradual weakening trend are expected during the next few days.
Please read the latest HIGH SEAS FORECAST issued by the National
Hurricane Center, at the website
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml. The latest NHC
Forecast/Advisory and Public Advisory can be read at
www.hurricanes.gov for more details.

Gale Warning Associated with Invest Area (AL91):
A central Atlantic tropical wave is near 41W from 17N southward
through a 1008 mb low (AL91) at 11N41W, and moving west at 15 to
20 kt. Scattered moderate to isolated strong convection is seen
from 07N to 16N between 36W and 44W. A large area of fresh to
locally strong E to SE winds with 7 to 10 ft seas are present from
10N to 19N between 35W and 42W. These winds are expected to become
gale force near 13N43W on Wednesday. Please read the latest HIGH
SEAS FORECAST issued by the National Hurricane Center, at the
website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more
information on the gale warning.

AL91 is about half way between the Cabo Verde Islands and Lesser
Antilles. Environmental conditions are forecast to be conducive
for development, and a tropical depression or storm is expected to
form in the next day or so while the system moves west-
northwestward across the central tropical Atlantic. Please read
the latest Tropical Weather Outlook issued by the National
Hurricane Center, at the website
https://www.nhc.noaa.gov/gtwo.php?basin=atlc&fdays=2 for more
information

...TROPICAL WAVES...

A western Caribbean tropical wave is near 84W from 19N southward
across Honduras, Nicaragua and Costa Rica into the East Pacific.
It is moving west at 10 kt. Aided by mid-level diffluent flow,
scattered showers and thunderstorms are occurring from 15N to 20N
between 81W and 84W.

...MONSOON TROUGH/ITCZ...

A monsoon trough enters the Atlantic along the Mauritania coast
just south of Nouakchott, and curves southwestward to 09N20W. An
ITCZ continues from 09N20W to 07N32W. Scattered moderate isolated
strong convection is noted from 06N to 09.5N between 21W and 27W.
Widely scattered moderate convection is found near and up to 160
nm northwest of the monsoon trough. Similar convection is present
near and up to 180 nm north of the ITCZ.

...GULF OF MEXICO...

A broad surface trough extends southwestward from the western
Florida Panhandle to the eastern Bay of Campeche. Isolated
thunderstorms are occurring across the central Gulf. Another
surface trough runs southwestward from northeastern Florida to the
Florida Keys. Widely scattered showers and isolated thunderstorms
are evident from the Yucatan Channel northeastward to the
northeastern Gulf. Moderate SE winds and seas of 2 to 4 ft are
noted at the southeastern Gulf, including the Yucatan Channel and
Straits of Florida. Gentle to moderate E to SE winds and 1 to 2 ft
seas prevail for the rest of the Gulf.

For the forecast, the broad surface trough will drift slowly
westward through Wed night before dissipating. Unsettled weather
will persist across the eastern half of the Gulf through Wed
night. Meanwhile, gentle to moderate NE to E winds and slight seas
will prevail across the basin through early Thu. Winds may
increase over the northern Gulf by Friday as high pressure
ridging strengthens over the southeastern United States.

...CARIBBEAN SEA...

Convergent easterly trades are coupling with strong upper-level
divergent flow to trigger scattered showers and isolated
thunderstorms near Haiti and southeastern Cuba. Farther east,
isolated thunderstorms are noted near the Lesser Antilles. Strong
thunderstorms related to a tropical wave are producing locally
fresh to strong winds and 5 to 7 ft seas from the Gulf of Honduras
to near the Cayman Islands. Moderate ENE to E winds and seas at 5
to 7 ft dominate the central basin. Light to gentle monsoonal
winds and seas of 2 to 4 ft exist near Costa Rica and Panama.
Gentle to moderate ENE to SE winds and 3 to 5 ft seas prevail
elsewhere in the basin.

For the forecast, seas have started to build across the waters
east of the Leeward Islands ahead of Tropical Storm Philippe well
to the east. Strong thunderstorms mentioned above are forecast to
gradually diminish later tonight. High pressure north of the area
will support moderate to fresh trade winds across most of the
eastern and central basin into midweek, with fresh to strong
pulses off northwest Venezuela and northeast Colombia mainly
during the overnight and early morning hours through Wed morning.

...ATLANTIC OCEAN...

Refer to the SPECIAL FEATURES section above for details on
Tropical Storm Philippe and a Gale Warning related to Invest
AL91.

Convergent southeasterly winds to the east of a surface trough
over Florida are triggering widely scattered showers and isolated
thunderstorms from the northwest Bahamas northward to beyond 31N.
Refer to the Monsoon Trough/ITCZ section for additional weather in
the Atlantic Basin. The Atlantic Ridge associated with both the
Bermuda and Azores Highs is supporting light to gentle winds and 3
to 6 ft seas in moderate northerly to easterly swell north of 25N
between 30W and the Georgia-Florida coast. Near the Canary
Islands, gentle to moderate with locally fresh NNE to NE trades
and seas of 6 to 8 ft are present north of 18N between the
northwest Africa coast and 30W. Fresh to strong with locally
near-gale easterly winds and seas of 10 to 14 in mixed swells are
seen from 20N to 25N between 45W and 54W. Otherwise, gentle to
moderate with locally fresh ENE to E winds and 6 to 8 ft seas in
large northerly swell are evident from 20N to 25N between 30W and
60W. Farther west, gentle to moderate ENE to ESE winds and 3 to 6
ft seas are found from 20N to 25N between 60W and the Bahamas.
Outside the direct impact from Philippe and AL91, including the
Gale Warning, gentle to moderate NE to SSE winds and seas of 3 to
6 ft in moderate northerly swell are present from 10N to 18N/20N
between the central Africa coast and 55W. Farther west, gentle to
moderate ENE to SE to SW winds and seas at 6 to 9 ft in large
easterly swell exist from 10N to 20N between 55W and the Lesser
Antilles. Light to gentle monsoonal and southerly winds and 5 to 7
ft seas in mixed swells prevail for the remainder of the Atlantic
Basin.

For the forecast west of 50W, Tropical Storm Philippe will move
to 17.3N 52.7W Wed morning, 18.4N 54.5W Wed afternoon, 19.2N 56.1W
Thu morning. It will then reach near 19.7N 57.9W Thu afternoon,
weaken to a tropical depression near 20.0N 59.3W Fri morning, and
20.1N 61.0W Fri afternoon. Philippe will become a remnant low as
it moves to near 20.2N 64.0W Sat afternoon. Rough seas ahead of
the storm have moved W of 55W, and will continue to spread east of
65W through the end of the week. Elsewhere, seas may build by Thu
north of the Bahamas and east of Florida in NE swell.

$$

Forecaster Chan
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