[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 061805
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
205 PM EDT Thu Jul 6 2017

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 1200 UTC surface analysis and satellite imagery through
1745 UTC.

...SPECIAL FEATURES...

Tropical Depression Four is centered near 13.2N 42.6W at 06/1500
UTC or about 1096 nm east of the Lesser Antilles moving WNW at 18
kt. Estimated minimum central pressure is 1008 mb. Maximum
sustained wind speed is 25 kt with gusts to 35 kt. Scattered
to isolated moderate convection is located within 315 nm of the
center of the depression, primarily in the western semicircle.
Please see the latest NHC Public Advisory under AWIPS/WMO headers
MIATCPAT4/WTNT34 KNHC and the full Forecast/Advisory under the
AWIPS/WMO headers MIATCMAT4/WTNT24 KNHC for more details.

...TROPICAL WAVES...

A tropical wave is just off the W coast of Africa with axis
extending from 16N18W to 04N18W, moving W at 5-10 kt within the
last 24 hours. The wave is in a region of favorable to neutral
wind shear. However, extensive intrusion of Saharan dry air and
dust to the wave environment hinder convection at the moment N of
08N. Scattered moderate convection is from 05N to 08N between 16W
and 23W associated with the monsoon trough.

A tropical wave is over the central Atlantic just E of the Lesser
Antilles. Its axis extends from 20N58W to 08N60W and has been
moving W at about 15 kt during the last 24 hours. The wave is in
a region of favorable to neutral wind shear. However, intrusion
of Saharan dry air and dust to the wave environment hinder deep
convection at the time. Shallow moisture and upper level
diffluence support isolated showers from 09N to 15N between 56W
and 62W.

A tropical wave located over the W Caribbean has an axis near 81W
extending from 09N to 22N, moving west at around 20 kt during the
past 24 hours. The wave is in a region of unfavorable wind shear.
However, shallow moisture and upper level diffluent flow between a
low over the SE Gulf of Mexico and a broad ridge covering the W
Caribbean support scattered to isolated heavy showers and tstms W
of 78W.

A tropical wave is moving over the SW Gulf of Mexico with axis
near 95W extending from 14N to 25N, moving westward at about 15-20
kt. The wave is in a region of favorable to neutral wind shear. Shallow
moisture and upper level diffluent flow between a low over central Mexico
and a broad ridge anchored in the EPAC waters support scattered
heavy showers and tstms S of 26N W of 90W.

...ITCZ/MONSOON TROUGH...

The Monsoon Trough extends from 11N15W to 06N20W to 04N28W. The
Intertropical Convergence Zone extends from 04N28W to 03N40W to
07N51W. Aside from the convection related to Tropical Depression
Four and the tropical wave off the coast of Africa, scattered
showers are observed in the vicinity of the ITCZ from 01N to 07N between
37W-48W.

...DISCUSSION...

GULF OF MEXICO...

A weak surface ridge extends across the northern Gulf anchored by
a 1022 mb high near 29N86W, which is forecast to stall through
tomorrow morning. A tropical wave is in the SW basin, enhancing
showers and tstms in this area, including the Bay of Campeche.
Refer to the tropical waves section above for further details. Isolated
showers are elsewhere in the E basin being supported by shallow
moisture and diffluent flow aloft between an upper level ridge
anchored in the SE CONUS and a low just N of western Cuba. Scatterometer,
ship, and buoy observation indicate that the surface winds across
the Gulf are light to gentle, except for moderate SE flow in the
eastern Bay of Campeche associated with the aforementioned
tropical wave. Little change in this pattern is expected during
the next couple of days.

CARIBBEAN SEA...

A tropical wave is moving across the W Caribbean supporting
showers and tstms W of 78W. Refer to the section above for
details. The moderate pressure gradient over the Caribbean between
the Azores high to the northeast and lower pressure over NW
Colombia and central America is maintaining moderate to fresh
tradewinds over the basin, except over the waters from 10N to 18N
between 70W and 80W where fresh to strong easterlies are present.
A tropical wave is entering the E Caribbean later today supporting
showers across the Windward Islands and adjacent SE Caribbean
waters. Little change is expected through Friday morning, but
with diminishing winds Friday night.

...HISPANIOLA...

Isolated showers and tstms are occuring over the western half of
the Dominican Republic being supported by shallow moisture and
upper level diffluent between a ridge anchored in the SW N Atlc
and a low in the south-central Caribbean. No major convection is
anticipated for the Island through Saturday night associated with
a tropical wave.

ATLANTIC OCEAN...

Tropical Depression Four and two tropical waves were analyzed
over the tropical North Atlantic. Refer to the Special Features
and Tropical Waves sections above for details. Aside from the
convection associated with Tropical Depression Four and the ITCZ
previously mentioned, no other significant convection is
occurring. A broad 1029 mb surface high is centered north of our
area near 35N34W. This high continues to dominate the weather
across the area. To the south of the high and away from Tropical
Depression Four described above, moderate to fresh trade winds
prevail across the basin. This synoptic pattern will change little
through the next couple of days.

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

$$
Ramos
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