[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 080557
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
157 AM EDT Tue May 8 2018

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 32N. 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.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coastal sections of Sierra
Leone near 09N13W to 04N15W. The ITCZ continues from 04N15W to
01N37W to 03S45W along the coast of Brazil. Scattered moderate
convection is noted from 01N to 03N between 13W and 18W, and from
01N to 03N between 35W and 50W.

...DISCUSSION

GULF OF MEXICO...

A very broad mid-latitude trough continues to move across the
southeastern U.S. The main impact of the trough is north of the
region, limiting mid/upper support for a stalling and dying
frontal boundary reaching from South Florida to the south central
Gulf. 1020 mb high pressure is centered over the northwest Gulf
behind the front, maintaining generally gentle to light winds and
slight seas. Moderate to fresh northerly winds are noted over the
far eastern Gulf between the high pressure and lower pressure off
the Georgia coast, supporting 2 to 4 ft seas. No significant
shower activity is observed.

The high pressure will shift east toward the northeast Gulf
through Fri, then into the Atlantic Sat. This will maintain
moderate NE to E winds and 2 to 4 ft seas across the eastern Gulf
through the period. High daily temperatures over the Yucatan
peninsula will set up a weak thermal trough each evening, which
will move over the eastern Bay of Campeche during the morning then
dissipate during the afternoon each day beginning Wed.

CARIBBEAN SEA...

A sharp elongated trough reaches from central Cuba to the
southwest Caribbean near 15N80W. Riding over the central Atlantic
is supporting moderate to fresh E to SE winds across the basin
east of the trough axis. Buoy observations and altimeter
satellite data show 5 to 7 ft west of the trough. Generally
gentle to light northerly winds are noted across the Caribbean. Moderate
to fresh trade winds are noted across the tropical north Atlantic
waters west of 55W, south of the main ridge. Seas are reaching 8
ft, but this includes a component of decaying NE to E swell.
Regional radar mosaics indicate a few warm topped showers south of
the central Cuba near the trough, supported by a broad mid/upper
level trough south of the Caymans. A few fast moving trade wind
showers are observed moving off the Atlantic into the Leeward and
Windward Islands. Otherwise, no significant weather is noted.

The trough is expected to drift westward and weaken through mid
week, but will remain the focus for showers and a few
thunderstorms through late Tue as the supporting mid/upper trough
lifts northeast and dampens out. Trade wind flow will increase
over the south central Caribbean by Fri night as ridging builds
north of the region. Little change otherwise in the forecast.

ATLANTIC OCEAN...

A cold front reaches from weak 1013 mb low pressure centered
north of the area, approximately 180 nm southeast of Charleston,
SC, ahead of a positively tilted mid/upper trough reaching from
the southern Appalachians to the lower Mississippi Valley.
Scattered moderate to isolated strong convection is active from
180 to 240 nm east of the frontal boundary. The front is making
very slow progress eastward as most of the supporting dynamics
aloft are lifting northward. Fresh to strong southerly winds
persist ahead of the front north of 27N between 70W and 75W,
between the low pressure off the Carolinas and the main
subtropical ridge centered farther east over the central Atlantic.
Buoy observations and an altimeter satellite pass from 01 UTC
indicated 5 to 7 ft seas in open waters. Higher seas and stronger
gusts are possible near the aforementioned stronger thunderstorms
ahead of the front.

The winds ahead of the front will diminish to gentle to moderate
by Wed as the low pressure lifts north. High pressure ridging
extending east to west along 31N Fri through Sat night will
generate gentle to moderate E to SE winds over the forecast
waters, except that fresh to locally strong winds will pulse
between the southeast Bahamas and the coast of Hispaniola.

Farther east, a large mid/upper trough reaches from the Azores to
near 18N50W. Despite upper support on the east side of the
mid/upper trough, no significant moisture is noted north of the
ITCZ as deep layer moisture remains limited. A front over the
eastern Atlantic is keeping the subtropical ridge fairly weak east
of 40W, and latest scatterometer satellite passes indicated
generally moderate trade wind flow as well, except for the fresh
trades west of 55W which is south of 1031 mb high pressure
centered near 35N45W. Concurrent altimeter passes indicate seas
are generally 5 to 7 ft over central and eastern portions of the
tropical and subtropical North Atlantic.

For additional information please visit
http://www.hurricanes.gov/marine

$$
Christensen
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