Tropical Weather Discussion
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000
AXNT20 KNHC 181120
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
805 AM 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 0600 UTC surface analysis and satellite imagery through
1045 UTC.

...SPECIAL FEATURES...

Tropical Depression Julia is centered near 31.3N 76.7W at
18/0900 UTC or about 190 nm east-southeast of Charleston, South
Carolina and about 245 nm south-southwest of Cape Hatteras,
North Carolina moving north-northwest at 4 kt. Estimated minimum
central pressure is 1010 mb. Maximum sustained wind speed is 25
kt with gusts to 35 kt. Scattered moderate to isolated strong
convection is from 30N-32N between 75W-78W. Scattered showers
and isolated thunderstorms are from 28N-32N between 72W-75W.
Isolated showers and thunderstorms are from 27N-30N between 68W-
72W. Please see the latest NHC Forecast/Advisory under the
AWIPS/WMO headers MIATCMAT1/WTNT21KNHC for more details.

Tropical Storm Karl is centered near 17.7N 42.3W at 18/0900 UTC
or about 1115 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. Clusters of
scattered moderate to isolated strong convection are from 17N-
21N between 38W-43W. Please see the latest Forecast/Advisory
under the AWIPS/WMO headers MIATCMAT2/WTNT22 KNHC for more
details.

A tropical wave located between Africa and the Capo Verde
Islands extends along 22W from 9N-18N with a 1007 mb low along
the wave near 13N22W. Wave and low are moving west-northwest at
5 to 10 kt over the past 24 hours. Wave coincides with a global
model 700 mb trough and remains embedded within a surge of
moisture as shown on the Total Precipitable Water imagery.
Clusters of scattered moderate to isolated strong convection are
from 15N-19N between 17W-23W.   Environmental conditions are
expected to be conducive for development, and a tropical
depression is likely to form by mid-week. Regardless of
development, this system could bring rain and gusty winds to 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...

Tropical wave approaching the Lesser Antilles extends along 61W
from 11N-20N moving west 10 to 15 kt over the past 24 hours.
Wave coincides with a global model 700 mb trough but remains
within an area of dry air. No associated showers or deep
convection.

...ITCZ/MONSOON TROUGH...

Monsoon trough extends across Africa into the Tropical Atlantic
near 16N16W then through the 1007 mb low in the Special Features
section above, continuing along 9N29W to 12N37W. The ITCZ is
being disrupted by the Tropical Storm Karl. Clusters of
scattered moderate to isolated strong convection are from 6N-10N
between 14N-18N, from 9N-15N between 22W-27W, and from 7N-10N
between 28W-33W.

...DISCUSSION...

...GULF OF MEXICO...

An upper ridge dominates the Gulf again this morning anchored
near 26N91W and extending a upper ridge axis southwest over
Mexico near Tampico and northeast across Georgia and the
Carolinas then into the northwest Atlantic. At the surface, a
weak surface ridge covers the east Gulf of Mexico anchored by a
1019 mb high over western North Carolina. A mid level trough
extends from southeast Louisiana along 90W to 28N covering the
north/central Gulf and generating scattered showers and possible
isolated thunderstorms north of 27N to over the north Gulf coast
between 89W-91W. The diurnal surface trough has dissipated but
lingering moisture continues to generate scattered showers and
isolated thunderstorms over the Bay of Campeche south of 20.5N
between 93W-96W. The mid level trough will continue to bring
possible showers and thunderstorms to the north Gulf through
tonight before it weakens on Monday. The surface ridge will
shift slowly west across the north Gulf through Monday night.
The diurnal surface trough will develop over the Yucatan
peninsula during the late afternoons, then move into the
southwest Gulf waters late each night into the early morning
hours before dissipating.

...CARIBBEAN SEA...

A cutoff upper low is over the far northwest Caribbean centered
along the coast of the Yucatan near 19N88W extending an upper
trough north to the west tip of Cuba. This is generating
scattered showers and isolated thunderstorms south of 18N to the
coast of Honduras west of 84W and north of 19N to the coast of
Cuba between 78W-82W. The monsoon trough extends south of the
Caribbean waters but is still generating scattered showers and
isolated thunderstorms in the southwest Caribbean within 45 nm
along the coast of Panama and Costa Rica. An upper ridge
dominates the central Caribbean anchored near 13N79W and
extending an upper ridge axis across east Cuba and through the
Windward Passage. A second cutoff upper low is over the east
Caribbean near 14N66W supporting a surface trough that extends
from 20N64W through the Virgin Islands to 14N65W generating
scattered showers and isolated thunderstorms from 15N-19N
between 63W-66W, including the Virgin Islands and eastern Puerto
Rico. The remainder of the Caribbean is under clear skies again
this morning. Fresh to strong trade winds will develop along the
coast of Colombia today through Monday night before diminishing.
The surface trough will continue to move west in tandem with the
upper trough. A tropical wave will enter the east Caribbean this
morning and interact with the upper low and surface trough as it
moves across the east Caribbean. The tropical wave will reach
the central Caribbean on Wednesday.

...HISPANIOLA...

Skies remain clear across the island this morning. The upper low
and associated surface trough over the east Caribbean will move
west to over the Dominican Republic early Monday, then over the
remainder of the island by Monday night. This 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 are Tropical Storms Karl in the
central Atlantic and Tropical Depression Julia off the southeast
CONUS. See Special Features above. An upper trough over the west
Atlantic covers the area north of 22N west of 70W while the
upper ridge over the central Caribbean extends across east Cuba
and through the Windward Passage to 30N62W. To the east of the
upper ridge is a surface trough that extends from 31N58W through
a weak 1015 mb low near 27N65W to 22N71W. Scattered showers and
isolated thunderstorms are north of 25N east of the surface
trough to 57W. An upper low is centered near 22N55W generating
scattered showers and possible isolated thunderstorms from 21N-
23N between 53W-57W. The east Atlantic, north of Tropical Storm
Karl is dominated by a surface ridge anchored by a 1029 mb high
near the Azores. Tropical Depression Julia is expected to move
slowly north-northwest through Monday night before turning
northward and becoming a remnant low through Tuesday night.
Tropical Storm Karl is expected to move west through tonight
then turn west-northwest through Tuesday night.

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

$$
PAW


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