Tropical Weather Discussion
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AXNT20 KNHC 082352

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
652 PM EST Fri Dec 8 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.



A frontal system is in the Gulf of Mexico extending as a
stationary front across northern Florida to 29N83W where it
transitions to a warm front that continues to a 1008 mb low near
26N89W. A cold front extends from the low to the eastern Bay of
Campeche near 19N92W. A strong ridge continues to build in the
wake of the front, supporting gale-force winds north and southwest
of the front with seas reaching up to 18 ft. These conditions are
forecast to prevail through Saturday morning. Scattered moderate
convection is observed along the fronts and low covering the area
east of 90W. Please read the latest NWS High Seas Forecast under
AWIPS/WMO headers MIAHSFAT2/FZNT02 for more details.


The frontal system over the Gulf of Mexico is forecast to enter
northwest Caribbean on Saturday morning. Strong to near gale-
force winds will will follow the front as it moves across Cuba
Saturday. Gale-force winds are forecast to develop off the coast
of Nicaragua Sunday morning as the tail of the front reaches Costa
Rica. There is a high risk of heavy rains for Costa Rica and
western Panama Saturday evening through Monday morning associated
with this front. Please read the latest NWS High Seas Forecast
under AWIPS/WMO headers MIAHSFAT2/FZNT02 for more details.


The monsoon trough extends across the Africa coast near 06N11W to
east Atlantic waters near 05N21W. The Intertropical Convergence
Zone extends from that point to 02N41W. Scattered moderate
convection is from 01N to 06N between 03E to 22W.



The main story of the basin is the frontal system that extends
across the central and eastern Gulf. Gale-force winds prevail
across the northwestern and southwestern Gulf waters. Please
refer to the section above for details. moderate to fresh
southwest winds are noted southeast of the low/fronts with
isolated showers. This system is forecast move off the basin to
the west Atlantic and the northwest Caribbean Saturday morning.


A surface trough along 82W persists in the southwest Caribbean in
a deep moisture region and underneath upper-level diffluent flow.
This scenario allows for the continuation of scattered moderate
convection south of 20N between 75W-83W. To the east, a surface
trough (remnants of a stationary front) extends along 14N and
east of 70W with isolated showers. Scatterometer data depicts
moderate to fresh trades across the basin except fresh to strong
winds south of 13N between 74W-76W. A center of low pressure will
develop near the southern extent of the surface trough within the
next 24 hours, allowing for the showers activity in that region to
continue. Furthermore, a cold front forecast to enter the west
Caribbean waters on Saturday morning increasing the shower
activity through the weekend. Potential heavy rain and gale-force
winds are forecast for portions of Nicaragua, Costa Rica and
Panama. See the Special Features section for further details.


Fair weather prevails across the island as a surface high centered
over the central Atlantic extends through the area. Isolated
convection could develop in the afternoon hours through the
weekend due to daytime heating.


A stationary front extends across the west Atlantic from a 1010
mb surface low near 31N78W to northeast Florida near 30N81W. Scattered
moderate convection is along and behind of the front to near 72W.
To the east, a 1025 mb surface high is centered near 30N58W,
which is forecast to move northeast Saturday. A stationary front
extends from a 1012 mb surface low near 30N39W to 19N37W then
becomes weak to 14N53W. A trough continues from that point to
14N61W. Scattered moderate convection is along and east of the
front mainly north of 24N between 30W-34W. A surface ridge prevails
east of the front. During the next 24 hours, the frontal
boundary over the west Atlantic will push southeast through
Saturday. The low pressure area in the central Atlantic and will
move southwest over our area of discussion enhancing convection.
Strong winds will follow its front. Please read the latest NWS
High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 for
more details.

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