[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 171745
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Thu Jun 17 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 1200 UTC surface analysis and satellite imagery through
1720 UTC.

...SPECIAL FEATURES...

Cloudiness and thunderstorms associated with a broad area of low
pressure over the southwestern Gulf of Mexico have become a little
better organized today. This system is expected to move generally
northward, and a tropical or subtropical depression is likely to
form over the west-central Gulf of Mexico tonight or early Friday.
Heavy rainfall will continue over portions of Central America and
southern Mexico during the next couple of days. Heavy rains will
also begin to affect portions of the northern Gulf Coast on
Friday. Please consult products from your local meteorological
service for more information. Please refer to the latest Tropical
Weather Outlook issued by the NWS National Hurricane Center at
www.hurricanes.gov for more details on this area.

...TROPICAL WAVES...

A newly analyzed Atlantic tropical wave axis is along 23W from
the Cabo Verde islands near 18N southward, and is moving west at
10 to 15 kt. Scattered moderate convection is seen from 01N to
07N between 16W and 31W.

Another Atlantic tropical wave axis is along 42W from 18N
southward, moving west at 15 to 20 kt. Scattered showers are
noted from 10N to 13N between 39W and 43W.

A Caribbean Sea tropical wave axis is over the Lesser
Antilles and Windward Islands near 62W from 20N southward into
Venezuela, and is moving W at around 15 to 20 kt. Scattered
moderate convection is present from 06N to 17N between 57W and
68W. Stronger thunderstorms might produce fresh gusty winds
across the Lesser Antilles and Windward Islands. Additional
scattered moderate convection is noted inland over eastern
Venezuela.

Another Caribbean Sea tropical wave axis in the western Caribbean is
analyzed along 82W from 18N southward over western Panama, and is
moving west at 5 to 10 kt. Scattered moderate to locally strong
convection is evident from the coast of Panama north to 11N between
75W and 83W.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coast of Africa near 11N15W
to 04N26W. Segments of the ITCZ then continue westward from
04N26W to 06N39W and 05N43W to the coast of French Guiana at
05N53W. Scattered moderate convection is found near French Guiana
and Suriname from 04N to 06N between 46W and 57W.

GULF OF MEXICO...

Refer to the Special Features section above for details on a broad
low pressure area over southwestern Gulf of Mexico.

A surface trough curves southeastward from near the Texas-Mexico
border at 25N97W to the low pressure center near 20N93W. A
band of scattered thunderstorms is found along the coast of Mexico
within 50 nm of the trough axis. A second surface trough extends
northeastward from the low to the north central Gulf near 28N88W.
Near both troughs, fresh to locally strong winds were detected by
the latest scatterometer passes. Aided by upper-level divergent
flow, scattered moderate to isolated strong convection is
occurring from the Yucatan Channel north to 27N between the
Florida Gulf coast and 92W. This convection is also impacting
portions of the NW Caribbean.

A stationary front stretches eastward from near New Orleans at
29N89W across the northeastern Gulf to northern Florida at
30N84W. No convection is noted with the front at this time.
Gentle to moderate E winds are noted in the northern Gulf north
of 26N, moderate to locally fresh E-SE winds are noted south of
26N and east of 94W, with moderate to fresh NE-N winds west of
94W. Finally, in the eastern Bay of Campeche, winds shift
cyclonically to S around the broad low pressure. Seas are mainly
in the 3-5 ft range, except 4-6 ft in the south central Gulf,
southeast Gulf, and Straits of Florida.

For the forecast, the broad area of low pressure over the SW Gulf
of Mexico is producing widespread but disorganized cloudiness,
showers, and thunderstorms. This system is expected to move
northward, and a tropical or subtropical depression is likely to
form over the west-central Gulf of Mexico tonight or early Friday.
Regardless of development, heavy rainfall will continue to affect
most of the basin through Fri night, and the N and NE basin
offshore the remainder weekend. High pressure is forecast to
build in across the basin in the wake of the low Sat night into
early next week.

CARIBBEAN SEA...

A tropical wave is moving across the western Caribbean and another
wave is near the Lesser Antilles. Refer to the Tropical Waves
section above for details.

The eastern Pacific Ocean monsoon trough extends across Panama to
NW Colombia near 10N75W. In the NW Caribbean, scattered moderate
to isolated strong convection is noted north of 18N and west of
84W, including inland over the Yucatan Peninsula. This convection extends
north into the Gulf of Mexico.

Fresh to strong tradewinds were detected by the latest
scatterometer pass in the south central Caribbean. The strongest
winds extend from the coast of Colombia north to 13N between 71W
and 77W. Mainly moderate to fresh trades prevail elsewhere in the
basin, except gentle to moderate in the SW Caribbean south of
11N. Seas of 4-8 ft throughout the basin, except 6-9 ft in the
area of strong winds off in the south central Caribbean.

For the forecast, a ridge of high pressure north of the basin
combined with lower pressure over Venezuela and Colombia will
support pulsing fresh to strong trades over the S central
Caribbean and Gulf of Honduras during the weekend and into Tue.
Fresh to strong trades will expand in areal coverage and reach
Hispaniola adjacent waters over the weekend. Elsewhere, moderate
to fresh trades will prevail, except light to gentle variable
winds over Panama and Costa Rica adjacent waters.

ATLANTIC OCEAN...

A pair of tropical waves are moving across the basin. Refer to
the Tropical Waves section above for details.

Diffluent flow aloft continues to support scattered moderate
convection over the Florida Peninsula and western Atlantic mainly
north of 25N and west of 70W. To the east, a surface ridge
dominates the entire Atlantic forecast area anchored by the
Bermuda-Azores High located north of the area. Fresh to locally
strong SW winds are occurring in the W Atlantic north of 30N
between 68W and 71W. Moderate to fresh trades dominate south of
22N west of 50W. Gentle to moderate trades prevail elsewhere,
except from 18N to 24N between the west coast of Africa and 24W
where fresh N-NE winds persist due to a locally tight pressure
gradient. Seas are 7 to 10 ft in this area of fresh winds. In the
Bahamas, seas are 2-4 ft. Outside of these areas, seas of 5 to 8
ft prevail across the waters south of 22N, with mainly 4 to 7 ft
seas north of 22N.

For the forecast west of 65W, a ridge of high pressure across the
area will retreat eastward today enabling a trough to move
through the northern forecast waters through Fri. High pressure
will then return to the area this weekend into early next week.
Fresh to strong winds are expected to pulse at night over
Hispaniola adjacent waters during the forecast period and over
Puerto Rico adjacent waters tonight.

$$
Mahoney/Chan
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