Tropical Weather Discussion
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AXNT20 KNHC 240005

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
804 PM EDT Sun Apr 23 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
2345 UTC.


The pressure gradient between a center of low pressure in the SE
CONUS merging with a 1007 mb center of low pressure moving across
southern Florida, and a surface ridge moving to central Atlc
waters will support the development of gale force winds in the SW
N Atlc starting near 1200 UTC Monday. Gale conditions will cease
on Tuesday morning as both the low and the high move N of the
area. Seas in this region during this period will range between 8
to 12 ft. Please see the latest High Seas Forecast product under
the WMO header FZNT02 KNHC and under the AWIPS header MIAHSFAT2
for further details.

A cold front associated with the center of low pressure in the SE
CONUS extends from the Florida Panhandle SW to near Tampico,
Mexico. Strong high pressure behind this front anchored by a 1022
mb high over NE Mexico tightens the gradient over the W Gulf to
support gale force winds N of the front to 25N W of 96W. Latest
scatterometer data confirms the gale winds. Gale winds are
forecast to diminish tonight as the center of high pressure
dissipates, thus relaxing the pressure gradient in the region.


The Monsoon Trough extends across the western Africa coast from
07N12W to 03N20W to 02N26W. The Intertropical Convergence Zone
continues from 02N26W to 01N34W to the coast of Brazil near
02S43W. Scattered moderate convection and isolated tstms are from
05S to 07N between 12W and 40W.



A middle to upper level low over W Tennessee with associated
trough extends S across the Gulf to a base over the NW Caribbean.
The same supports a surface 1007 mb low N of Georgia from which a
cold front extends S across the Florida Panhandle to the central
Gulf near 25N90W to near Tampico, Mexico. There is not deep
convection associated with the front due to very dry conditions at
the surface and aloft as indicated by water vapor and CIRA LPW
imagery. Gale force winds are behind the front W of 96W. See the
special features section for further details. A surface low
pressure is ahead of the front, over S Florida, however the
convection associated with it has moved out of the Gulf already.
Besides the area of gale winds, N moderate to fresh winds dominate
W of the cold front while light to moderate winds are ahead of it.
The front is forecast to move out of the basin early Tuesday


A middle level diffluent environment across the central Caribbean
along with abundant low level moisture across most of the basin
continue to support scattered heavy showers across Hispaniola and
adjacent waters. Scattered to isolated showers extends W across
the Windward Passage and E Cuba and E over the Mona Passage. A
short-wave upper trough over central America along a middle
diffluent environment in that region favor scattered showers
within 120 nm off the coast of Nicaragua, Costa Rica and N Panama.
Dry air aloft across the remainder basin support fair weather.
Except for S of Hispaniola where fresh trade winds are present,
light to moderate winds dominate elsewhere. Showers across the
north-central Caribbean will continue through Tuesday, extending
to Puerto Rico Monday and Tuesday. Otherwise, the tail of a cold
front is forecast to move across the NW Caribbean waters Monday
through Tuesday.


Abundant low level moisture across the northern Caribbean and a
middle level diffluent wind environment support showers across
Hispaniola and adjacent waters, including the Windward and the
Mona Passage. Heavy showers will continue over tonight through
Tuesday morning.


Except for the tail of a dissipating cold front over the north-
central Atlc extending from 30N35W to 26N39W with isolated showers
extending E to 27W, the remainder basin N of 16N is being
dominated by surface ridging. W of the dissipating front, the
ridge is anchored by a 1020 mb high near 28N63W, which is moving N
of 30N over the next 24 hours. The E ridge is centered by a 1020
mb high near 30N19W, which is forecast to dissipate by Monday
afternoon. Otherwise, a cold front is expected to enter the SW
Atlc Monday night and gale force winds will develop between the
front and the ridge to the east. See special features for further
details of the gale.

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