Tropical Weather Discussion
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000
AXNT20 KNHC 180554
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
205 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 0000 UTC surface analysis and satellite imagery through
0515 UTC.

...SPECIAL FEATURES...

Tropical Depression Julia is centered near 30.6N 76.5W at
18/0300 UTC or about 220 nm southeast of Charleston, South
Carolina moving northwest at 3 kt. Estimated minimum central
pressure is 1010 mb. Maximum sustained wind speed is 25 kt with
gusts to 35 kt. No associated deep convection. Scattered showers
and isolated thunderstorms are within 90 nm of the center over
the northeast quadrant and within 75 nm of a line from 28N75W to
33N73W. Please see the latest NHC Forecast/Advisory under the
AWIPS/WMO headers MIATCMAT1/WTNT21KNHC for more details.

Tropical Storm Karl is centered near 17.8N 41.3W at 18/0300 UTC
or about 1175 nm east of the Leeward Islands moving west at 10
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 18N-
21N between 36W-42W. 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 21W from 9N-17N with a 1007 mb low along
the wave near 15N21W. Wave and low are moving west-northwest 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.
Scattered moderate to isolated strong convection is from 15N-18N
between 17W-22W. 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 in the west
Tropical Atlantic extends along 60W from 11N-21N 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 9N28W to 11N37W. The
ITCZ is being disrupted by the Tropical Storm Karl. Clusters of
scattered moderate to isolated strong convection are from 8N-15N
between 22W-26W and from 7N-10N between 26W-33W. Clusters of
scattered moderate convection are within 90/120 nm along
the coast of Africa south of 9N west of 10W.

...DISCUSSION...

...GULF OF MEXICO...

An upper ridge dominates the Gulf again tonight anchored near
27N91W and extending a upper ridge axis southwest over Mexico
near Tampico and northeast along the eastern seaboard into the
northwest Atlantic. At the surface, a weak surface ridge extends
from a 1019 mb high over western North Carolina over the
northeast Gulf to 26N90W. A mid level low is centered over
southeast Louisiana covering the north/central Gulf generating
scattered showers and possible isolated thunderstorms north of
28N to over the north Gulf coast between 85W-87W and north of
26N to over the north Gulf coast between 87W-92W. The diurnal
surface trough extends from 22N88W to inland over the Yucatan
peninsula to northwest Guatemala generating scattered showers
and possible isolated thunderstorms over the east Bay of
Campeche south of 21N east of 93W. The mid level low will
continue to bring showers and thunderstorms to the north Gulf
through today. The diurnal surface trough will develop over the
Yucatan peninsula each evening, moving into the southwest Gulf
waters late each night, then dissipating each morning.

...CARIBBEAN SEA...

A cutoff upper low is over the far northeast Caribbean near
19N86W extending an upper trough south to the coast of Honduras
and north to the west tip of Cuba. This is generating isolated
showers and possible isolated thunderstorms from 17N-20N west of
84W. The monsoon trough extends across the southwest Caribbean
along 9N from Colombia to Panama/Costa Rica generating scattered
showers and isolated thunderstorms south of 10N. An upper ridge
dominates the central Caribbean anchored near 15N77W and
extending an upper ridge axis through the Windward Passage. A
second cutoff upper low is over the east Caribbean near 14N66W
supporting a surface trough that extends along 64W from 13N-19N
and generating scattered showers and isolated thunderstorms from
13N-19N between 62W-66W, including the Leeward Islands, the
Virgin Islands and moving over Puerto Rico. The remainder of the
Caribbean is under clear skies again tonight. Fresh to strong
trade winds will develop along the coast of Colombia tonight and
again Sunday night. The surface trough will continue to move
west in tandem with the upper trough. A tropical wave will enter
the east Caribbean tonight reaching the central Caribbean Monday.

...HISPANIOLA...

Skies are clear across the island tonight. The upper low and
associated surface trough over the east Caribbean will move west
to over the Dominican Republic Sunday night, then across the
remainder of the island by Monday night. This will bring
moisture and accompanying showers and thunderstorms to the
island starting Sunday night spreading west 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 23N west of 70W while the
upper ridge over the central Caribbean extends through the
Windward Passage to 30N65W. To the east of the upper ridge is a
surface trough that extends from 31N59W through a weak 1014 mb
low near 27N64W to 22N68W. Scattered showers and isolated
thunderstorms are north of 26N east of the surface trough to
54W. An upper low is centered near 23N53W generating scattered
showers and isolated thunderstorms from 20N-24N 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 be a remnant low later
today moving slowly northward through Tuesday. Tropical Storm
Karl is expected to move west through Sunday night then turn
west-northwest through Tuesday.

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

$$
PAW


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