[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 181805
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
205 PM EDT SUN SEP 18 2016

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 Julia is centered near 31.8N 77.1W at
18/1500 UTC or about 161 nm east-southeast of Charleston, South
Carolina moving west at 2 kt. Estimated minimum central pressure
is 1010 mb. Maximum sustained wind speed is 25 kt with gusts to 35
kt. Scattered showers and isolated tstms are within 240 nm SE
semicircle. Please see the latest NHC Forecast/Advisory under the
AWIPS/WMO headers MIATCMAT1/WTNT21KNHC for more details.

Tropical Storm Karl is centered near 18.0N 43.4W at 18/1500 UTC
or about 1051 nm east of the Leeward Islands moving west at 11
kt. Estimated minimum central pressure is 1006 mb. Maximum
sustained wind speed is 35 kt with gusts to 45 kt. Scattered
showers are within 180 nm N semicircle. Please see the latest
Forecast/Advisory under the AWIPS/WMO headers MIATCMAT2/WTNT22
KNHC for more details.

A vigorous tropical wave is in the E Atlantic near the Cabo Verde
Islands extending from 08N to 18N with axis near 23W moving W at 5
to 10 kt over the past 24 hours. The wave is associated with a
1007 mb low located near 12N23W expected to move near 15N26W
within the next 24 hours. Scattered heavy showers and isolated
tstms are from 07N to 17N E of 28W. Environmental conditions
are expected to be conducive for development, and a tropical
depression is likely to form by mid-week while the low moves
west-northwestward to northwestward across the eastern tropical
Atlantic.  Regardless of development, locally heavy rains and gusty
winds are possible in the Cabo Verde Islands during the next couple
of days. This system has a medium chance of tropical formation
within the next 48 hours. Please see the Tropical Weather Outlook
under AWIPS/WMO Headers MIATWOAT/ABNT20 KNHC for more details.

...TROPICAL WAVES...

A tropical wave is entering the E Caribbean waters. The wave
extends from 10N to 20N with axis near 62W moving west at 15 kt
over the past 24 hours. The wave is in a region of favorable deep
layer wind shear, however CIRA LPW imagery from the surface to 850
mb show patches of dry air within its environment that likely
limit the convective activity to isolated showers across the
Lesser Antilles.

...ITCZ/MONSOON TROUGH...

Monsoon trough extends across Africa into the Tropical Atlantic
near 17N16W then through the 1007 mb low associated with the wave in
the Special Features section above, continuing along 7N28W to
08N36W. The ITCZ is being disrupted by the Tropical Storm Karl.
For convection information, please refer the tropical wave in
special features.

...DISCUSSION...

...GULF OF MEXICO...

Weak surface ridging prevails across the Gulf of Mexico anchored
by a 1017 mb high in the NE basin near 28N87W. The exception is a
surface trough in the far NW Gulf extending from 30N91W to 28N94W
to 26N97W that support isolated showers over SE Louisiana coastal
waters. The surface ridge provides variable gentle winds in the NE
portion of the basin and return flow of the same magnitude
elsewhere. Abundant moisture across the Gulf being advected from
the Caribbean and favorable deep layer wind shear support isolated
showers NW of a line from 28N82W to 20N95W. Ridging will be the
main feature across the basin the next two days.

...CARIBBEAN SEA...

The main features in the basin are a surface trough moving across
Puerto Rico and a tropical wave that is moving across the Lesser
Antilles. The surface trough extends from 21N65W to 15N65W and the
wave axis is near 62W. These two features along with a broad
upper level low over the E Caribbean support scattered showers and
tstms over Puerto Rico and adjacent waters and the basin E of 70W.
For more details on the tropical wave, see section above. An area
of diffluence in the NW Caribbean support a surface trough from
21N86W to 16N87W and associated scattered to isolated showers S of
20N W of 83W. Otherwise, the E Pacific monsoon trough support
scattered showers and tstms within 60 nm of northern Panama.
Similar activity is observed within 90 nm off the coast of
Nicaragua. Otherwise, moderate trades dominate the basin, except
within 120 nm off the coast of Colombia where fresh to locally
strong winds are present mainly due to orographic effects. By
Tuesday near sunrise, the tropical wave will merge with the
surface trough W of Haiti.

...HISPANIOLA...

Skies remain clear across the island mainly due to strong
subsidence from aloft as noted in water vapor imagery. An upper
low and associated surface trough currently over Puerto Rico will
move west to over the Dominican Republic early Monday, then over
the remainder of the island by Monday night. A tropical wave will
merge with this trough near sunrise Tuesday when the system is
expected to be W of Haiti or moving across the Windward Passage.
These features will bring moisture and accompanying showers and
thunderstorms to the island starting late tonight, spreading west,
and continue through Wednesday.

...ATLANTIC OCEAN...

Primary features of concern in the forecast waters are Tropical
Storms Karl in the central Atlantic and a vigorous tropical wave
currently near the Cape Verde Islands. Please refer to the Special
Features and tropical waves sections above. In the SW basin,
scattered showers and tstms associated with Tropical Depression
Julia N of the area are N of 28N between 71W and 78W. Farther
east, a surface trough extends from 31N60W to 24N66W with scattered
showers and isolated thunderstorms north of 24N between 57W and
65W. The east Atlantic, north of Tropical Storm Karl is dominated
by a surface ridge anchored by a 1030 mb high near the Azores.

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

$$
RAMOS
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