Tropical Weather Discussion
Issued by NWS
AXNT20 KNHC 121655
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1155 AM 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 1200 UTC surface analysis and satellite imagery through
A 1010 mb partially occluded low is centered 25N53W that is
supported aloft by a middle to upper level low nearly collocated
with the surface feature near 26N51W. The associated cold front
extends from the low S-SW to 22N51W to 18N54W to the Lesser
Antilles near Dominica and into the SE Caribbean Sea. Near gale
to gale force NE winds are occurring across the discussion waters
within 660 nm of the low center in the NW quadrant. Latest
scatterometer pass around 12/1300 UTC confirms the large area of
increased winds due to the strength of the pressure gradient. See
latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/
FZNT02 KNHC for more details.
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
this afternoon. These conditions are expected to pulse during the
late night and early morning hours through Sunday. 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
02N23W. The Intertropical Convergence Zone axis extends from
02N23W to the Equator near 28W the along the Equator to 44W.
Isolated moderate convection is S of 04N between 04W-12W...and S
of 04N between 26W-51W.
GULF OF MEXICO...
Middle to upper level ridging remains anchored across the eastern
Gulf waters that supports surface ridging with axis extending
from the Florida peninsula SW to southern Mexico near 20N97W.
Moderate to occasional fresh E-SE winds are occurring across the
basin this afternoon with mostly fair skies noted on visible
satellite imagery. 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.
West-southwesterly flow aloft prevails over the basin between
broad upper level troughing over Central America and the adjacent
east Pacific region and an upper level ridge anchored over
northeastern South American continent. Another middle to upper
level low is also noted on water vapor imagery centered over the
central Atlc near 26N51W supporting a shear line analyzed from
16N58W W-SW across Dominica to 14N70W to 11N83W. Scattered
showers and isolated tstms are occurring from 11N-14N between
81W-84W...with isolated showers elsewhere within 90 nm either
side of the shear line. In addition...strong to near gale force NE
winds are occurring in close proximity to the coast of Colombia
due to a strengthened pressure gradient across the region.
Otherwise...fresh to strong trades persist elsewhere. The shear
line boundary is expected to remain nearly stationary or drift
slightly eastward through the overnight hours and become diffuse
Fresh to strong NE winds prevail across the island and adjacent
coastal waters this afternoon. This wind field is due to a
relatively strong pressure gradient across the region and SW North
Atlc waters. Isolated showers are expected to continue as the NE
flow persists through the remainder of the week into the weekend.
A middle to upper level low is centered near 26N51W that supports
a nearly collocated 1010 mb surface low...as mentioned in the
Special Features section above. The associated cold front extends
from the low S-SW to 16N57W and becomes a shear line into the
eastern Caribbean Sea. Scattered showers and isolated tstms are
occurring from 19N-31N between 44W-56W with isolated showers
elsewhere within 90 nm either side of the cold front and shear
line boundary. The remainder of the SW North Atlc is under the
influence of a surface ridge anchored by a 1035 mb high centered N
of Bermuda near 37N64W. Mostly moderate to fresh NE to E winds
prevail on the southern periphery of the ridge which are forecast
through Sunday. The low pressure area along the front is expected
to drift southward through the remainder of the week and weaken
well E of the Lesser Antilles by Saturday night into Sunday.
Farther east...a surface trough extends from 15N42W to 23N37W
providing focus for isolated showers within 60 nm either side of
the boundary. This area of activity continues to be enhanced by
marginal middle to upper level diffluence.
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