Tropical Weather Discussion
Issued by NWS
AXNT20 KNHC 172348
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0805 PM EDT MON OCT 17 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 1800 UTC surface analysis and satellite imagery through
Hurricane Nicole is centered near 42.7N 42.6W at 2100 UTC or
about 500 nm ESE of Cape Race Newfoundland and is accelerating
toward the NE at 22 kt. Estimated minimum central pressure is
962 mb. Maximum sustained wind speed is 65 kt with gusts to 80
kt. Widely scattered moderate convection is within 180 nm of
center. See latest Forecast/Advisory under AWIPS/WMO headers
MIATCMAT5/WTNT25 KNHC for more details.
Nicole has developed a very large wind field over the past
weekend which has generated a tremendously large wave field.
Large swell from Nicole is propagating in all directions from
the system center and will spread across most of the North
Atlantic Basin during the next few days. Large NNE to NE swell
is reaching the coasts of the Bahamas, Hispaniola, Puerto Rico
and the Lesser Antilles late this afternoon, is expected to
build further overnight through Tuesday. These large swells will
create very high and powerful breaking waves along the coasts
and local reefs, and produce extremely dangerous rip currents in
the surf zone. Wave runup along the beaches will also have the
potential to cause beach erosion and coastal flooding. Consult
the local meteorological service in your area for specific
details on these hazards.
Tropical wave is in the vicinity of 24N-25N southward of 14n
moving W at 10-15 kt. A 1010 mb low is centered at the southern
extend of the wave near 07.5N25W and remains embedded within the
Monsoon Trough. Scattered moderate to strong convection is from
08.5N-14.5N between 20W-28W, and is brushing across southern
portions of the Cabo Verde Islands.
The Monsoon Trough extends from the African coast near 09.5N14W
to 10N18W to low pressure near 07.5N25W to 06N31W to 07N39W.
Scattered moderate isolated strong convection is from 00N-05N
between 15W-18W. Widely scattered moderate isolated strong
convection is from 01N-07N between 24W-33W.
GULF OF MEXICO...
Water vapor imagery indicates dry sinking air aloft covering the
NE two-thirds of the basin as an upper level trough continues to
sink S across the Florida peninsula and portions of the SW North
Atlc. Strong NE to ENE prevailing across the Atlantic coastal
waters of Florida are spreading across the peninsula and into
far eastern Gulf to near 85W, where skies are mostly cloud free.
A weak low level trough extends from near the mouth of the
Mississippi River to near 24N88W. Low level convergence along
the E side of this trough is producing short narrow lines of
shallow convection that is shifting slowly W. Mostly fair
conditions prevail W of this trough as a surface ridge axis
extends from the Carolinas SW across the remainder of the
northern Gulf. Gentle to moderate anticyclonic winds continue
and are expected to persist through Tuesday as they increase
slightly Tuesday night into Wednesday. The next cold front is
expected to emerge off the Texas and Louisiana coasts by
Thursday night into early Friday.
An upper level anticyclonic circulation is anchored over the SW
Caribbean this evening near 11N77W. Mostly clear skies and fair
conditions are noted on satellite imagery E of 68W, however W of
68W moisture and cloudiness increase as a broad cyclonic
circulation is developing in the low levels from central America
to Jamaica. A diffluent upper level environment continues to
allow for scattered showers and isolated strong tstms from 09N-
18N between 76W-88W...including large portions of Panama and
Costa Rica. A large cluster of showers and tstms is across
portions of the south-central Caribbean S of 16N between 68W and
72W extending into coastal portions of Venezuela and Colombia.
Gentle to moderate S to SE winds have developed this afternoon
across the E half of the Caribbean, while light trades generally
prevail elsewhere E of 80W this evening. On Tuesday, global
models are suggesting cyclogenesis to occur N of Hispaniola and
Puerto Rico, which is already resulting in a disruption of the
usual trade wind flow across the eastern Caribbean. As a low
center organizes Tuesday through Wednesday and lifts generally
northward, lingering weak surface troughing will extend across
the Greater Antilles into the SW Caribbean through Saturday.
SE low level winds across the eastern Caribbean this afternoon
have led to seabreeze convergence across the northern coastal
areas of the Dominican Republic where scattered moderate
isolated strong convection is occurring. To the north of
Hispaniola, a shear line extends from near 21.5N60W to 24N74W.
This low-level flow regime in tandem with an upper level trough
noted on water vapor imagery over the SW North Atlc is likely to
maintain some of this active convection well into the night
timehours as the upper trough shifts slightly ESE. 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.
A middle to upper level trough is noted on water vapor imagery
over the SW North Atlc, NW Bahamas to Cuba, with a relatively
broad base reaching to near 20N80W. The troughing aloft is
generating maximum diffluence to the east and inducing a surface
trough analyzed from 28N74W to 23N73W. At the base of this
surface trough, a 1008 mb surface low looks to have developed,
where surface obs from the Grand Turks have reported W to NW
winds since this afternoon. A large area of scattered showers
and tstms is occurring from 20N-30N between 60W-72W, with the
strongest convection occurring along the shearline described
above, extending from 21N53W to the surface low. The low
pressure near 23N73W will shift ENE tonight, then attempt to
become better organized Tuesday as it begins to lift northward.
Strong easterly winds are expected to occur within 240 nm across
northern portions of this low and the shearline in its vicinity
during the next 24 hours.
Farther east, the central Atlc is under the influence of a
stationary front extending from the circulation associated with
Hurricane Nicole well to the N of the discussion area. The front
extends from 32N38W SW to 22N46W to 21N53W where the shear line
begins. Widely scattered showers and isolated tstms are
occurring within 90 nm either side of the front. Finally, across
the eastern Atlc, a middle to upper level cyclone is noted in
water vapor imagery in the vicinity of 29N12W. This low supports
widely scattered convection aloft across portions of Morocco. To
the NW of this, a 1012 mb low centered W-SW of the Iberian
peninsula near 37N16W with a cold front extending SW from the
low center to 32N19W the stationary into a weak 1017 mb low
centered near 30N23W. The frontal troughing then extends to the
SW with another surface trough analyzed from 24N27W to 16N35W.
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