Tropical Weather Discussion
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AXNT20 KNHC 130010

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
705 PM EST Thu Jan 12 2017

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
2315 UTC.


A strong pressure gradient between lower pressure across South
America and a ridge anchored across the SW North Atlc is
generating near gale to gale force winds in the SW Caribbean
Sea. Gale conditions are expected to pulse during the late night
and early morning hours through Sunday. Expect on Fri 13/0600
UTC from 10N-13N BETWEEN 74W-78W NE winds 30-35 KT with seas 11-
15 ft. This gale will last six hours. Expect on Sat 14/0600 UTC
from 10N-13N BETWEEN 74W-78W NE winds 30-35 KT with seas 11-14
ft. This gale will again last six hours. See latest NWS High
Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for
more details.


The Monsoon Trough extends from the African coast near 10N14W to
02N22W. The Intertropical Convergence Zone axis extends from
02N22W to 00N30W to 01N42W to the coast of South America near
01S49W. Scattered moderate convection is from 01N-03N between
19W-22W. Isolated moderate convection is from 01N-05N between



10-20 kt E to SE surface return flow is over the Gulf of Mexico
maintaining warm temperatures. The entire Gulf is void of
precipitation. An upper level high is centered over central
Florida near 29N81W. Very strong subsidence covers the entire
Gulf. This overall synoptic pattern is expected to persist
through the remainder of the week and into the weekend. The next
front is not expected until Tuesday night into Wednesday along
the Texas coast.


Gale to near gale conditions are along the coast of N Colombia.
See above. A shear line extends from E of St. Lucia near 14N60W
to 13N70W to the coast of Nicaragua near 12N84W. Scattered
showers are within 60 nm of the shear line. Elsewhere, radar
imagery shows scattered showers over Puerto Rico advecting in
from the Atlantic. Hispaniola has similar conditions especially
over the upper elevations. In the upper levels, an upper level
ridge is over the Caribbean Sea with axis along 70W. Strong
subsidence cover the entire Caribbean. Expect showers along the
shear line to persist for the next 24 hours becoming diffuse Sat.


Fresh to strong NE winds prevail across the island and adjacent
coastal waters. This wind field is due to a relatively strong
pressure gradient between the NW Caribbean and the Atlantic low
near 23N54W. Scattered showers are over the northern portions of
the island especially over higher elevations. Expect showers to
continue as the NE flow persists through the remainder of the
week into the weekend.


A 1032 mb high is centered over the W Atlantic near 40N58W. A
ridge axis extends SW to N Florida. A 1009 mb occluded low is
centered near 23N54W that is supported aloft by an upper level
low nearly collocated with the surface feature near 25N54W.
Another 1010 mb triple point surface low is centered near
25N52W. A cold front extends S-SW from this low to 20N52W to E
of the Lesser Antilles near 14N60W. Near gale force winds are
occurring NE of the surface lows. Expect in 24 hours for a 1010
mb surface low to be located near 22N52W with a surface trough
extending S to 17N56W with showers. The remainder of the frontal
system will dissipate.

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