[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 130005
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
805 PM EDT Thu Jul 12 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 1800 UTC surface analysis and satellite imagery through
2300 UTC.

...SPECIAL FEATURES...

CHRIS is a post-tropical cyclone, and it is expected to pass over
or near the Avalon Peninsula of southeastern Newfoundland late
afternoon and early evening today. The position of CHRIS at
12/1800 UTC was 45.8N 56.2W. The estimated minimum central
pressure was 989 mb. The maximum sustained wind speeds were 60
knots with gusts to 75 knots. A frontal boundary is surrounding
CHRIS at this time. Please read the latest NHC forecast/advisory
under AWIPS/WMO headers MIATCMAT3/WTNT23 KNHC for more details.

...Gale Warning in the south-central Caribbean Sea...

Gale-force NE-to-E winds are imminent, from 11N to 12.5N between
74W and 76W. Sea heights will range from 10 feet to 14 feet. These
conditions are forecast to last for 12 hours or so. Gale-force
NE-to-E winds will return on Friday around sunset, from 11N to
13N between 74W and 76W. The sea heights will range from 10 feet
to 13 feet. This area is off the coast of Colombia. Please read
the High Seas Forecast, under the AWIPS/WMO headers HSFAT2/FZNT02
KNHC, for more details.

...TROPICAL WAVES...

A tropical wave extends its axis along 30W/31W from 07N-19N. The
wave is relocated slightly farther E based on visible satellite
imagery. Scattered showers are noted where the wave meets the
Monsoon Trough, mainly from 07N-11N between 28W-32W. This wave
coincides with a good surge of moisture based on the TPW product,
and model diagnostic guidance also confirms its presence. A new
outbreak of Saharan dust is noted on either side of the wave's
axis.

A tropical wave has its axis along 46W from 07N-20N, moving west
at 15-20 kt. Saharan dust follows this wave inhibiting convection
at this time. Satellite imagery indicates some inverted-V pattern
in the cloud field associated with this wave.

A low amplitude tropical wave extends its axis from 08N65W to
17N64W, moving west 10-15 kt. Saharan dust surrounds the wave
inhibiting convection over the Caribbean Sea. However, the wave
appears to enhance some convective activity over NE Venezuela.
GFS computer model suggests an increase in moisture in association
with this wave reaching the central Caribbean by Friday.

Another tropical wave is moving across the western Caribbean. Its
axis along 86W from 08N-21N, moving west at 10-15 knots. Saharan
Air Layer from CIMSS shows African dust behind the wave's axis
covering the basin all the way to the Lesser Antilles. The wave is
helping to induce scattered moderate convection over the Gulf of
Honduras and the eastern parts of Honduras and Nicaragua. This
tropical wave will move westward across the Yucatan peninsula
this afternoon and across the SW Gulf tonight through Fri.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coastal sections of Senegal
near 14N17W to 08N37W. The ITCZ extends from 08N37W to 07N50W to
09N60W. Aside from the convection related to the tropical waves,
A cluster of moderate convection is near the west coast of Africa
and covers the area from 06N-10N E of 16W to the coast of Africa.
Similar convection is also noted just E of Trinidad and Tobago
where some shower and thunderstorm activity has been reported this
morning. This activity covers from 09N-11N between 56W-62W.

...DISCUSSION...

GULF OF MEXICO...

A surface ridge dominates the Gulf waters anchored by a 1018 mb
high centered over the NW Gulf near 27N92W. Scattered showers with
embedded tstms are noted over much the area, more concentrated
over the NE Gulf waters. This convective activity is enhanced by
an upper-level low over the SE Gulf, and a trough extending
westward from the low along 23N/24W. A weak surface trough is
analyzed along 89W north of 25N. This trough will move westward
through Fri while dissipating.

Weak high pressure will continue across the area through Mon.
A weak surface trough along 89W north of 25N will move westward
through Fri while dissipating. Another surface trough will move
westward off the Yucatan Peninsula each evening through Mon. It
will slightly enhance nocturnal winds and seas over the SW Gulf.
A tropical wave will move westward across the Yucatan peninsula
this afternoon and across the SW Gulf tonight through Fri.

CARIBBEAN SEA...

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

A gale warning is in effect for the south-central Caribbean.
Refer to the Special Features section above for details.

The NW Caribbean Sea tropical wave near 87W will move inland the
Yucatan peninsula and Central America this evening. Atlantic Ocean
high pressure will build across the region behind the tropical
wave to freshen tradewinds across the central Caribbean waters.
Winds will pulse to strong to near gale force each night off
Colombia through Tue, except to minimal gale force tonight and Fri
night.

ATLANTIC OCEAN...

Chris is now a post-tropical cyclone and the last advisory was
issued at 12/1500 UTC. Please read the Special Features section
for details. Swells generated by the storm will affect parts of
the coast from North Carolina northward to New England during the
next couple of days, even though Chris is moving away from the
United States. Swells will spread northward along the southern
coasts of Nova Scotia and Newfoundland today. It is possible that
these swells may cause life-threatening surf and rip current
conditions.

An elongated area of showers and thunderstorms associated with the
remnants of Beryl is located about 400 miles west-southwest of
Bermuda. As of 1200 UTC, a weak low pressure of 1015 mb is
analyzed near 29N72.5W with a trough extending westward toward
Florida. Little or no development is expected through Friday while
the system moves northeastward. However, environmental conditions
could become a little more favorable over the weekend when the
disturbance will be moving northward or north-northeastward over
the warm waters of the western Atlantic and interacting with a
strong upper-level trough. The latest Tropical Weather Outlook
gives this system a low chance of tropical cyclone formation
during the next 48 hours.

An area of showers and tstms covers the Atlantic waters from
23N-29N between 56W-61W. Lightning density indicates frequent
lightning within the observed convective activity. This activity
is the result of a surface trough extending from 28N59W to 21N61W
interacting with an upper-level low.

A surface trough extends from just east of Fort Pierce Florida
northeastward to 28N75W and to a weak 1016 mb low at 31N71W. The
low will lift north of the 31N tonight, while the trough lingers
across the northwestern waters through early Sun night. Central
Atlantic high pressure will build westward across the eastern part
of the basin Fri through Mon, with the resultant pressure gradient
allowing for fresh to strong E winds south of 23N. East winds
will pulse to strong between the southeastern Bahamas and Hispaniola
from the afternoons to overnight hours during the period.

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

$$
MT
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