Tropical Weather Discussion
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AXNT20 KNHC 190605

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
105 AM EST Mon Feb 19 2018

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.


Caribbean Sea Gale Warning: A tight surface pressure gradient
continues between a surface high pressure in the western Atlantic
and lower surface pressures in northern sections of S America.
This pattern supports winds pulsing to minimal gale force near the
coast of Colombia through early next week. Wave heights within
the area of gale force winds will range between 12-17 ft. Please
read the latest NHC High Seas Forecast under AWIPS/WMO headers
MIAHSFAT2/FZNT02 KNHC for more details.


The monsoon trough axis extends from the coast of Africa near
07N12W southwestward to 03N15W and dips below the Equator at 19W
where it transitions to the ITCZ axis to 02S29W and to the coast
of S America at 03S39W. The ITCZ continues from that point to
03N39W. Scattered moderate isolated strong convection is within
120 nm S of the axis between 25W-29W, and within 60 nm N of the
axis between 18W-20W. Scattered moderate convection is within
30 nm of the axis between 12W-14W.



A surface ridge extends westward from a 1027 mb high centered
over the Atlantic near 28N64W to a 1023 mb high centered just
west of the coast of Florida at 29N83W, and weakens as it
continues to NW Gulf. The NW part of a surface trough extends off
the NW coast of Cuba to near 23N85W. A surface trough is along the
west coast of the Yucatan Peninsula. The earlier scattered
moderate convection noted near this trough has dissipated.
Isolated showers are S of 21N and E of 94W. Isolated showers
are S of 22N between 91W-95W. Patches of fog lifting northward
are seen over the NW Gulf early this morning. Expect these patches
of fog to linger through the morning, with other patches of fog
possible to form along and near the coastal sections of the N
central and NE portions of the gulf. Both buoy observations and
scatterometer data from last night indicate generally light to
gentle east to southeast flow N of of 26N, and gentle to moderate
east to southeast winds S of 26N, except for higher winds in the
moderate to fresh range E of 88W and W of 94W. Expect increasing
winds and building seas beginning on Mon as high pressure
strengthens in the western Atlantic Ocean. The thermal trough will
develop over the western Yucatan Peninsula Mon and Tue afternoon,
drift westward across the eastern Bay of Campeche during the
overnight hours, and then dissipate in the SW Gulf waters by the
late morning hours.


Please refer to the SPECIAL FEATURES section for details
regarding the Gale Warning near the coast of Colombia.

A tight pressure gradient across the basin created by the
combination of high pressure over the central Atlantic and lower
pressure over NW Colombia is producing strong east winds
throughout. These winds continue to quickly advect patches of
mainly broken low clouds westward along with passing isolated
showers, except over the far western Caribbean from 14N-18N W of
81W, including the Gulf of Honduras, where patches of overcast
to broken low clouds contain scattered showers. Overall shower
activity across the basin has decreased during the past 24 to 48
hours as abundant dry sinking air aloft maintains is influence on
the atmosphere. This same gradient will continue to support
pulsing winds of minimal gale force near the coast of Colombia
through early next week. Fresh to locally strong trade winds are
expected elsewhere across the Caribbean Sea. The high pressure
will be reinforced by a stronger one system on Mon. This stronger
system will bring increasing winds and building seas across the
eastern and central Caribbean, and the Tropical N Atlantic waters
possibly into the middle of next week.


Broad area of high pressure prevails across the basin, centered by
a 1027 mb high center near 28N64W and a 1024 mb high center near
30N37W. A weakness in the ridge is noted as a surface trough that
extends from 28N44W to 19N45W. A backdoor type cold front has
nudged southward to roughly along 31N between 72W-80W, becoming
a stationary front northwestward to inland Georgia at 32N81W. A
pre-frontal trough is just ahead of the front between 72W-76W.
Only scattered low clouds are seen along the trough, while very
minimal cloudiness is near the front. The cold front will become
stationary today and dissipate by early Tue. Satellite imagery is
depicting low clouds and fog over the extreme far northwest
waters along the NE Florida coast. These clouds and fog are slowly
moving inland that coast. The existing area of high pressure is
forecast to be fortified by stronger high pressure system through

Currently over the eastern portion of the Atlantic, extensive mid
and upper level moisture in the form of overcast to broken mid
and high level clouds is observed streaming northeastward from
northeastern S America to within 360 nm either side of a line
from 02N50W to 13N34W to 18N25W to the coast of Africa at 21N17W,
where the moisture thins out. This area of moisture and clouds
are driven by a rather strong jet stream branch that is along the
southeastern sector of a broad and persistent central Atlantic
upper level trough. Scattered moderate convection is within 60 nm
of a line from 01N37W to the Equator at 43W. Isolated showers are
possible elsewhere from the Equator to 11N west of 35W, and from
14N-21N between 17W-30W.

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