Atlantic Tropical Weather Discussion (Text)

AXNT20 KNHC 161803

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
203 PM EDT Thu Aug 16 2018

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 
1745 UTC.


The center of Subtropical Storm Ernesto at 16/1500 UTC is near 
42.0N 43.2W, or 510 nmi to the ESE of Cape Race in Newfoundland. 
Ernesto is moving NE at 14 knots. The estimated minimum central 
pressure is 1007 mb. The maximum sustained wind speeds are 40 
knots with gusts to 50 knots. Scattered moderate convection is 
from 39N to 46N between 39W and 44W. Please read the latest NHC 
forecast/advisory under AWIPS/WMO headers MIATCPAT5/WTNT35 KNHC 
for more details.


A tropical wave is in the E Atlc with axis extending from 06N-17N
along 23W, moving W at 10 kt. The wave is in a moderate deep 
layer wind shear environment, and CIRA LPW imagery shows dry air 
affecting the wave. These two factors are contributing to the 
lack of convection at this time.

A tropical wave is in the central Atlc with axis extending from
04N-16N along 49W, moving W at 20 kt. The wave is in a low deep 
layer wind shear environment, and CIRA LPW imagery shows abundant
low level moisture associated with it. These factors along with
upper level diffluence support scattered moderate convection and
isolated tstms from 07N-18N between 46W-60W. 

A tropical wave is in the E Caribbean with axis extending from
09N-18N along 65W, moving W at 15-20 kt. The wave is in a 
moderate to strong deep layer wind shear environment. GOES-16 
water vapor imagery at the lower levels show very dry air over 
this region of the Caribbean. There is no convection associated 
with this wave at this time. 

A tropical wave is in the Yucatan Peninsula S of 21N with axis
along 89W, moving W at 10-15 kt. GOES-16 water vapor imagery at 
the lower levels shows very dry air over this region, which in 
part is hindering convection at the time.


The monsoon trough extends from the coast of W Africa near 
12N16W to 09N29W. The ITCZ begins near 09N29W and continues to 
10N36W to 11N47W. Scattered moderate isolated strong convection is
from 11N-14N E of 18W. Isolated moderate convection is within 120
nm either side of the ITCZ between 27W-37W. For more information
about convection, see the tropical waves section. 



The Bermuda high extends a ridge axis SW across Florida and large
portions of the Gulf to 96W, and weak winds in the range of 5-10 
kt prevail in the region. Inflow of shallow moisture from the 
Caribbean by southeasterly wind along with a middle level inverted
trough in the E basin support scattered showers and tstms N of 
24N E of 90W. Winds in this region may be slightly higher in the 
range of 15-20 kt enhanced by the convection. Otherwise, a surface
trough is in the W Bay of Campeche supporting scattered heavy 
showers and tstms within 75 nm of the coast of Vera Cruz. Surface
ridging will prevail across the basin through early next week. 
Showers over the NE basin are forecast to continue through Sat 


CIRA LPW imagery shows abundant shallow moisture across most of 
the Caribbean. In the western basin, diffluent flow aloft supports 
a broad area of scattered showers and tstms from 11N-18N W of 76W.
A tropical wave is moving across the E basin, however both 
Saharan Air Layer dry air and strong deep layer wind shear are 
suppressing the development of convection at the time. Otherwise,
surface ridging extending from the Atlc continues to support 
fresh to near gale force winds in the south-central Caribbean that
is forecast to continue the next two days...strongest winds will 
be along the coast of Colombia. A tropical wave within 700 nm SE 
of the Lesser Antilles will move across the Islands Sat morning 
along with showers. 


The Bermuda high and the Azores high covers most of the Atlc ocean
mainly supporting fair weather. A weakness in the ridge is
analyzed as a 1019 mb low centered near 32N55W from which a
surface trough extends SW to 24N63W. Scattered showers and tstms
are within 150 nm ahead of the low and trough N of 27N. A large 
area of disorganized showers and thunderstorms is SE of Lesser 
Antilles associated with a tropical wave. Some development of 
this system is possible over the next couple of days while it 
moves west-northwestward toward the Windward Islands. By late 
Saturday, unfavorable environmental conditions should limit the 
chances for additional development while the system moves over the
eastern Caribbean Sea. Regardless of development, this system is 
likely to bring locally heavy rainfall to portions of the Lesser 
Antilles on Friday and Saturday. For further information 
associated with the tropical waves, see section above. 

For additional information please visit 


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Page last modified: Thursday, 16-Aug-2018 18:03:45 UTC