Tropical Weather Discussion
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AXNT20 KNHC 180649 CCA

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
205 AM EDT TUE OCT 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
0545 UTC.


Tropical Storm Nicole is centered near 44.8N 41.0W at 0300 UTC or
about 520 nm E of Cape Race Newfoundland, accelerating toward the
NE at 22 kt. Estimated minimum central pressure is 968 mb.
Maximum sustained wind speed is 60 kt with gusts to 75 kt. Widely
scattered moderate convection is N of 40N between 35W and 45W. Nicole
should transition to an extratropical cyclone on Tuesday. Large
swells associated with Nicole will affect the United States east
coast, the coast of Atlantic Canada, Bermuda, the Bahamas, the
Greater Antilles, the Leeward Islands, and the Azores islands for
the next few days, creating dangerous surf conditions and rip
currents. These swells are also likely to reach Europe and the
northwest coast of Africa in a day or two. See latest Forecast/Advisory
under AWIPS/WMO headers MIATCMAT5/WTNT25 KNHC for more details.

A middle to upper level trough is noted on water vapor imagery
over the W Atlc, with a relatively broad base reaching the
central Bahamas. The troughing aloft is supporting a 1006 mb low
near 23N72W and a large area of heavy showers and tstms from 19N
to 25N between 64W and 70W. The low is expected to slowly
intensify as upper-level winds become more conducive, and a
subtropical or tropical cyclone could form during the next day
or two as the low moves northward or north-northwestward. There
is a medium chance on this disturbance becoming a tropical
cyclone during the next two days.


Tropical wave is in the eastern Atlantic extending from 07N to 15N
with axis near 27W, expected to move W at 5-10 kt over the next 24
hours. The wave is in a region of unfavorable deep layer wind
shear and CIRA LPW imagery from surface to 850 mb show pockets of dry
air in the wave environment. Shallow moisture and divergent wind
flow aloft support scattered showers from 07N to 16N E of 30W,
including the Cape Verde Islands.


The Monsoon Trough extends from the African coast near 12N16W to
06N22W to 04N37W. The ITCZ begins near 05N42W and continues along
08N53W to 08N60W. Aside from the convection associated with the
tropical wave, widely scattered moderate convection is from 0N to
06N between 10W and 40W.



A broad surface ridge anchored by a 1018 mb high over Atlantic
waters near 34N70W extends SW across the SE CONUS and into the
Gulf where it provides gentle to moderate E to SE flow, except
over the E Bay of Campeche where winds are from the NE. Middle to
upper level ridging and strong dry air subsidence support stable
and fair weather conditions. Gentle to moderate anticyclonic
winds are expected to persist today, increasing slightly tonight
into Wednesday. The next cold front is expected to emerge off the
Texas and Louisiana coasts by Thursday night into early Friday.


A broad and elongated middle level trough extends across the W
Atlantic W of 60W and into the W Caribbean to a base over Panama
coastal waters. This middle level feature along with abundant
moisture in the region and favorable deep layer wind shear support
scattered showers within 90 nm of the Central America coast as
well as S of 20N between 67W and 82W. The extension of this trough
to the upper levels with a base across the central Bahamas and
upper ridging across the E Caribbean generate diffluent flow just
N of Hispaniola and Puerto Rico, thus supporting scattered to
isolated showers in both islands and adjacent waters. Generally
low pressure is across the basin at the surface with gentle to
moderate S to SE winds in the E half of the Caribbean and light
NE flow elsewhere W of 80W. Global models are suggesting
cyclogenesis to occur N of Hispaniola and Puerto Rico today, which
is already resulting in a disruption of the usual trade wind flow
across the eastern Caribbean. As a low center organizes today
through Wednesday and lifts generally northward, lingering weak
surface troughing will extend across the Greater Antilles into the
SW Caribbean through Saturday.


An upper trough over the W Atlantic waters with a base reaching
the central Bahamas and an upper ridge between 50W and 65W generate
diffluent flow to the NNE of Hispaniola, thus supporting
scattered showers across Haiti and the Windward Passage and isolated
showers in the Dominican Republic. The island is expected to
remain within an area of weak surface troughing through Wednesday
as cyclogenesis occurs across the SW North Atlc waters overnight
through Wednesday. Showers are expected to increase Tuesday night
and continue through the middle of the week.


A middle to upper level trough is noted on water vapor imagery
over the W Atlc, with a relatively broad base reaching the central
Bahamas. The troughing aloft is supporting a 1006 mb low near
23N72W and a large area of heavy showers and tstms from 19N to 25N
between 64W and 70W. The low pressure is forecast to shift ENE
this morning, then attempt to become better organized later today
as it begins to lift northward. Strong easterly winds are expected
to occur within 240 nm across northern portions of this low and
a shearline that extends from 20N52W to 22N63W to the low
center. See special features for further details. Farther east,
the central Atlc is under the influence of a stationary front
extending from the circulation associated with Tropical Storm
Nicole well to the N of the discussion area. The front extends
from 30N39W SW to 20N51W it transitions to a shear line.
Surface ridging is elsewhere in the eastern Atlantic.

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