[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 271750
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Sun Jun 27 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
1700 UTC.

...SPECIAL FEATURES...

Satellite imagery and nearby buoy and ship observations indicate
that a small low pressure system has formed about 500 miles
east-southeast of the Georgia-South Carolina border. Surface
pressures have begun to fall across the area, and showers and
thunderstorms have recently become better organized. Some additional
development of this system will be possible later today, and
especially on Monday when the system will move across the warmer
waters of the Gulf Stream, and a tropical depression could form
before the system makes landfall along the southern U.S. coast. The
low is expected to move westward today, and then west-northwestward
at about 15 mph on Monday, reaching the coast of the southeastern
United States by late Monday. An Air Force Reserve Unit
reconnaissance aircraft is scheduled to investigate the system
Monday afternoon, if necessary. Latest Tropical Weather Outlook
gives this system a medium chance of tropical cyclone formation
through 48 hours. Please, read the latest Tropical Weather Outlook
at www.hurricanes.gov, for more information.

...TROPICAL WAVES...

A tropical wave has been added to the 1200 UTC analysis/surface
map near the west coast of Africa based on satellite imagery,
tropical wave diagnostics and the Hovmoler diagram that clearly
shows the westward propagation of the wave. The wave is along 17W,
from near Dakar, Senegal southward. Scattered moderate to isolated
strong convection is noted on either side of the wave axis from
02N-12N between 12W-21W.

A second tropical wave is along 33W, from 16N southward. A 1009
mb low pressure center is analyzed along the tropical wave, near
10N. Scattered moderate convection is within about 210 nm NW
quadrant of the center. Some slow development of this system is
possible through the middle of the week while it moves a little
faster toward the west and then west-northwest at 15 to 20 kt.
Fresh easterly winds are noted per scatterometer data within
about 150 nm N semicircle of low. Please, read the latest
Tropical Weather Outlook at www.hurricanes.gov, for more
information.

The tropical wave previously located along 48W is no longer
discernible in satellite imagery or surface observations. As a
result, it was dropped from the surface map at 1200 UTC. Dry air
due to the Saharan dust is noted across the area.

Another tropical wave is along 57W, from 18N southward, moving W
at 10 to 15 knots. Convection is limited near the wave axis that
is surrounding by African dust.

A tropical wave is moving westward across the Caribbean Sea and
extends from Hispaniola to western Venezuela. It axis is near 72W
moving W at 10 kt. The wave is helping to induce some convective
activity near Cabo Beata, Dominican Republic as well as over the
Caribbean waters from 14N to 17N between 66W and 76W.

A tropical wave has reached the Yucatan Peninsula and northern
Central America. It axis is along 89W. Scattered showers and
thunderstorms are flaring up near the northern end of the wave
axis over the Yucatan Peninsula.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coastal plains of Guinea
near 11N15W to a 1009 mb low pressure located near 10N33W to
07N39W. The ITCZ axis continues from 07N39W to 06N45W to 08N55W
where a few showers are noted. The remainder of the convection is
associated with the tropical waves.

GULF OF MEXICO...

An upper-level low is still spinning over the NW Gulf supporting
scattered to numerous showers and thunderstorms, particularly on
the east side of the low located near 27N95W. A surface trough,
reflexion of this low, extends 27N91W to 24N96W. This trough over
the northwest Gulf will move inland over Texas through late
today, bringing scattered showers and thunderstorms as well as
fresh SE winds along with it. Winds and seas could be higher near
thunderstorms.

Otherwise, a weak ridge dominates the eastern Gulf producing
gentle to moderate SE winds. These winds will will persist
through the middle of the week between a trough over the far
southwest Gulf and the Atlantic ridge.

CARIBBEAN SEA...

Convection over the Caribbean is primarily associated with the
tropical waves described above. The EPAC monsoon trough extends
across Costa Rica and western Panama into northern Colombia.
Scattered showers and thunderstorms are noted S of 10N E of 81W,
including the Gulf of Uraba. A diffluent pattern aloft supports
scattered showers and isolated thunderstorms across the central
Caribbean, mainly from 13N to 16N between 79W and 82W.

A relatively weak pressure gradient spans the Caribbean Sea with
mainly gentle to moderate trades dominating. A surge in the trade
wind flow is noted behind the tropical wave located near 72W.
Fresh to locally strong easterly winds are occurring from 13N-16N
between 65W-68W with seas of 5 to 7 ft. Elsewhere, seas are in
the 3 to 5 ft range over the central Caribbean and Gulf of
Honduras, and 1 to 3 ft across the remainder of the basin.

The tropical wave currently along 72W will move westward across
the basin through Mon. This pattern will support moderate to fresh
trade winds over the south central Caribbean and off Honduras
early this week, with gentle to moderate trade winds elsewhere.
Then, winds will increase and seas will build slightly in most
areas by the middle of this week as high pressure north of the
Caribbean Sea extends into the basin in the wake of the above
mentioned tropical wave. Another tropical wave may approach the
Lesser Antilles late in the week.

ATLANTIC OCEAN...

Satellite imagery and nearby buoy and ship observations indicate
that a small low pressure system has formed about 435 nm east-
southeast of the Georgia-South Carolina border. Please, refer to
the Special Features section for more details. An altimeter pass
indicates seas of up to 11 ft within about 90 nm NE quadrant of
the low located near 29N71W at 1200 UTC.

A cold front is along 31N roughly between 40W and 52W. Scattered
showers are along the frontal boundary. The remainder of the
Atlantic forecast area is under the influence of a ridge anchored
on a 1023 mb high pressure located W of the Madeira Islands near
32N20W. Fresh northerly winds are seen just off the coast of W
Africa from 18N to 28N E of 20N, including the Canary Islands.
Seas are in the 5 to 7 ft range within these winds. Similar sea
heights are noted across the tropical Atlantic, mainly between 28W
and 55W where moderate to locally fresh trades prevail.

$$
GR
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