[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 111019
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Tue Jul 11 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 0600 UTC surface analysis and satellite imagery through
1000 UTC.

...TROPICAL WAVES...

A eastern Atlantic tropical wave has its axis along 24W from 05N
to 15N. It is moving westward at 10-15 kt. A small cluster of
moderate convection is noted where the wave meets the ITCZ near
10N24W.

An active and well defined tropical wave is approaching the Lesser
Antilles. Its axis extends from 19N54W to near the Suriname/Guyana
border. This wave is moving westward at about 20 kt. Scattered
moderate to isolated strong convection is seen mainly ahead of the
wave axis from 14N to 18N between 51W and 61W. Resent scatterometer
data indicate fresh to strong easterly winds on either side of
the wave, mainly N of 15N. Seas of 6 to 9 ft are within these
winds. The wave is located SE of an upper-level trough that extends
across the Leeward Islands into the eastern Caribbean to near
15N70W. This is likely enhancing the convective activity
associated to the wave that is already affecting the Lesser
Antilles, mainly S of Guadeloupe.

A western Caribbean Sea tropical wave has its axis along 81W,
south of 21N. It is moving westward at 10 to 15 kt. This wave
extends from central Cuba to western Panama. Scattered moderate
convection is present near the northern portion of the wave axis
affecting parts of central Cuba and the Cayman Islands. A cluster
of moderate to strong convection is over eastern Panama.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis reaches the Atlantic through the coast
of Mauritania near 19N16W and extends SW to near to 11N23W. The
ITCZ begins at 10N25W and continues to 06N40W and northwestward
to 10N55W. Aside from convection that is associated to tropical
waves, scattered moderate convection is noted on both side of the
ITCZ from 04N to 08N between 32W and 40W. A cluster of moderate to
isolated strong convection is along the coast of W Africa from 08N
to 11.5N E of 16W.

GULF OF MEXICO...

Isolated showers and thunderstorms are over the northern Gulf E of
92W, and over N florida ahead of an upper-level trough that
extends over the SE of United States. Similar convective activity
is also observed near the N coast of western Cuba. The latter is
the result of an upper-level low spinning over the NW Caribbean.
Another area of scattered showers and thunderstorm is noted in
the Bay of Campeche is association with a surface trough. The
remainder of the Gulf of Mexico is under the influence of the
western periphery of the broad subtropical ridge positioned over
the central Atlantic. This pattern is suppressing the development
of deep convection, especially in the southeastern part of the
Gulf, where a batch of dry Saharan dust is noted. Recent
scatterometer data clearly show the wind shift associated with the
trough that develops over the Yucatan Peninsula during the evening
hours. Moderate to fresh winds are associated with this trough.
Elsewhere across the Gulf waters, a gentle to moderate anticyclonic
flow is seen. Seas are generally 2 to 4 ft across the western
Gulf, and 1 to 3 ft across the eastern Gulf.

For the forecast, a ridge will continue to dominate the Gulf waters
while a trough will develop over the Yucatan Peninsula each
evening and move offshore. Under this weather pattern, moderate
to fresh winds will pulse north and west of the Yucatan peninsula
during the late afternoon and evening hours. Elsewhere, gentle
to moderate anticyclonic flow and slight seas will prevail.

CARIBBEAN SEA...

The pressure gradient between the 1025 mb high pressure located
over the central Atlantic near 27N42W and lower pressure in NW
South America sustain fresh to strong winds over the central
Caribbean, with strong to near gale force winds near the coast of
Colombia, and in the Gulf of Venezuela. This was confirmed by
recent satellite derived wind data. These winds also support seas
of 8 to 11 ft based on altimeter data, with the highest seas near
the coast of Colombia. An area of fresh to locally strong trade
winds with seas of 5 to 7 ft, is noted just S of Puerto Rico to
about 15N. Elsewhere, mainly moderate to fresh winds and seas in
the 3 to 5 ft range prevail, except in the lee of Cuba where
light and variable winds are noted with seas of 1 to 3 ft.

An upper-level low over the NW caribbean combined with a tropical
wave along 81W is helping to induce showers and thunderstorms
over parts of Cuba and the Cayman Islands and regional waters. The
western extent of an upper-level trough supports a band of
showers and thunderstorms across the eastern Caribbean roughly
along 15N and E of 73W.

For the forecast, fresh to strong winds and rough seas will continue
over the central Caribbean through the weekend. Strong to near gale
force winds are likely off Colombia and in the Gulf of Venezuela
mainly at night. Fresh to strong winds are expected in the Gulf of
Honduras tonight, then mainly moderate to fresh winds will prevail
the remainder of the forecast period. Moderate to fresh trade
winds and moderate seas will prevail over the E Caribbean and the
tropical Atlantic waters through Sat night. A tropical wave,
currently located along 56W, will bring an increase in winds and
seas across the waters just E of the Leeward Islands today, and
over the NE Caribbean tonight into on Wed. Fresh to strong NE winds
are expected in the Windward Passage ahead of the wave axis by Wed
night.

ATLANTIC OCEAN...

The Atlantic forecast region is dominated by a ridge anchored by a
1025 mb high pressure located near 27N42W. Another high pressure
center of 1022 mb is located mid-way between the Azores and the
Madeira Islands. Convection is limited across the basin. The
pressure gradient between the ridge and a frontal system off the
eastern United States is sustaining moderate to fresh southwest
winds north of 28N and west of 55W. Moderate to locally fresh E
trade winds are noted south of 22N and west of 55W. Seas in the
waters described are 4 to 7 ft. Elsewhere W of 55W, light to
gentle anticyclonic winds and seas of 3-5 ft prevail.

The Saharan Air Layer tracking product from CIMSS reveals that
another outbreak of Saharan dust is occurring off the coast of
Africa and will be propagating westward over the next several
days. African dust reaches Puerto Rico and Hispaniola. Moderate
to strong northerly winds are present between the Canary Islands,
and near the coast of Mauritania, particularly from 19N to 21N E
of 22W where seas are in the 7 to 9 ft range. Moderate to fresh
winds are noted elsewhere across the tropical Atlantic with seas
of 5 to 8 ft while mainly light to gentle winds are occurring
along the ridge axis with seas of 3 to 5 ft.

For the forecast W of 55W, a ridge will remain in place across the
forecast waters while weakening some by Wed as a developing low
pressure moves SE and crosses near the NE waters. Fresh W to NW
winds and seas to 8 ft, in association with the low, are expected
to impact the NE waters tonight into Wed. The northern end of a
tropical wave is forecast to affect the waters north of the
Leeward Islands and Puerto Rico on Wed, and north of Hispaniola,
including approaches to the Windward Passage by Wed night. In
addition, an area of fresh to locally strong E winds are expected
off Hispaniola over the next several days. Light to gentle winds
will persist along the ridge axis.

Looking ahead, an area of disorganized showers and thunderstorms
is currently located a few hundred miles to the east-northeast of
Bermuda. An area of low pressure is forecast to develop from this
area in the next day or so, and environmental conditions are then
forecast to be marginally conducive for further development. A
subtropical or tropical depression could form during the latter
part of this week as the system moves generally eastward. By the
weekend, the low should turn northward bringing the system over
cooler waters, likely limiting additional development. Refer
to the latest NHC Tropical Weather Outlook at www.hurricanes.gov
for more details.

$$
GR
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