[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 101734
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1234 PM EST Fri Mar 10 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
1715 UTC.

...SPECIAL FEATURES...
A low pressure of 1012 mb is located near 26N28W. A cold front
extends from the low center to 20N29W to 15N39W where it begins
to dissipate. The pressure gradient between this low and a high
pressure of 1029 mb located near 29N48W will likely support near
gale to gale force winds within about 90 nm west semicircle of
the low center this afternoon and tonight. Increasing rough or
very rough seas are expected with this system forecast to move
eastward to a position near 27N22W over the next 24 hours.
Scattered showers and isolated thunderstorms are related to this
feature, particularly in the NE quadrant.

...ITCZ/MONSOON TROUGH...
The Monsoon Trough axis extends from the African coast near 06N11W
to 03N21W. The Intertropical Convergence Zone axis extends from
03N21W to 02N30W to the Equator at 36W, and then to the coast of
Brazil near 2S45W. Isolated moderate convection is S of 04N between
18W and 26W. Scattered moderate convection is S of 02N west of
36W.

...DISCUSSION...

GULF OF MEXICO...
While upper level ridging prevails over much of the Gulf, mid-
level energy embedded within a weak shortwave trough is supporting
an area of scattered showers and tstms over the NW Gulf. Mosaic
Doppler Radar from the SE of United States confirmed the presence
of this convective activity. At 1500 UTC, a surface trough is
analyzed near the coast of Texas in association with this weather
conditions. A thermal trough will develop during the evening
hours over the Yucatan Peninsula before pushing offshore into the
SW Gulf each night. A surge of fresh to occasionally strong
northeast to east winds will accompany this trough through Sunday
night. Otherwise, the remainder of the Gulf is under the influence
of a surface ridge anchored by a 1023 mb high centered in the NE
Gulf near 28N85W. Mostly moderate E-SE winds are expected across
the basin the rest of today with the next weak frontal boundary
forecast to clip the north-central and NE Gulf waters tonight.
Moderate to fresh N-NE winds are briefly expected behind the front
over the NE Gulf through Saturday morning. A second and stronger
cold front is forecast to enter the Gulf region on Sunday. A weak
low is expected to form along the frontal boundary dragging a cold
front across the remainder of the Gulf through early next week.
Model guidance suggests fresh to strong NE winds behind the
front, and across the NW and N-central waters on Sunday, with seas
building to 6-7 ft.

CARIBBEAN SEA...
Winds have dimimished below gale force near the coast of Colombia.
The latest ASCAT pass provided observations of 20-25 kt NE-E winds
over the south-central Caribbean, with a few wind barbs of 30 kt.
As a result, the Gale Warning has been discontinued. Fresh to
locally strong trade winds are noted across the remainder of the
east and central Caribbean. These winds are forecast to diminish
tonight into Saturday across the basin as high pressure located
north of the area continues to shift farther eastward. A patch of
moisture is noted over the eastern Caribbean and just south of
Dominican Republic embedded in the trade wind flow. This cloudiness
was previously associated with a shear line, but currently
scatterometer data indicate the presence of a weak trough across
this area. This patch of moisture is forecast to move across
Hispaniola on Saturday. Aloft, a ridge dominates most of the
basin, producing moderate to strong upper level subsidence and
implied dry airmass.

...HISPANIOLA...
Moisture is forecast to increase across the island on Saturday
increasing the likelihood of showers and isolated thunderstorms,
mainly in the afternoon and early evening hours due to local
effects.

ATLANTIC OCEAN...
High pressure of 1029 mb located near 29N48W extends a ridge
westward across much of the forecast area west of 30W, including
the Bahamas and Florida. A low pressure of 1012 mb is located
near 26N28W. Near gale to gale force conditions are expected in
association with this low. Please, see Special Features section
for details. Scatterometer data show fresh to strong trade winds
across the southern periphery of the aforementioned high. Broken
stratocumulus clouds are over the central Atlantic in the wake of
the cold front and a dissipating cold front extending to near
Barbados in the Lesser Antilles. A cold front will enter the
discussion area this evening, reaching from 31N65W to the NW
Bahamas by early Saturday morning, and from 31N58W to south
Florida by Saturday night. Fresh to strong southwesterly winds are
expected ahead of the front, particularly N of 30N this evening.
Fresh to strong northerly winds will briefly follow the front
through late Saturday morning.

For additional information please visit
http://www.hurricanes.gov/marine

$$
GR

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