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Atlantic Tropical Weather Discussion

AXNT20 KNHC 160009

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
809 PM EDT Sun Jul 15 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 1800 UTC surface analysis and satellite imagery through 
2315 UTC.


Subtropical Storm Beryl is centered near 38.2N 63.8W at 15/2100 
UTC or about 356 nm N of Bermuda, moving ENE or 75 degrees at 5 
kt. The estimated minimum central pressure is 1010 mb. Maximum 
sustained wind speed is 35 kt with gusts to 45 knots. Latest 
satellite imagery shows that Beryl has weakened since yesterday as
noted by its exposed center that consists of broken to scattered 
low to mid-level clouds. Beryl should begin to weaken tonight when
it moves over colder water, and the cyclone is expected to 
degenerate into a remnant low pressure system late tonight or on 
Monday. Please read the latest NHC Forecast/Advisory under 
AWIPS/WMO headers MIATCMAT2/WTNT22 KNHC and high seas forecasts 
issued by the National Weather Service under AWIPS header 
NFDHSFAT1 and WMO header FZNT01 for more information.

SW Caribbean Sea gale warning: NE to E minimal gale force winds 
are near the coast of Colombia from 11N to 13N between 73W and 
76W. The gale is forecast to end 16/1500 UTC. Please read the 
High Seas Forecast, under the AWIPS/WMO headers HSFAT2/FZNT02 
KNHC, for more details.


A far eastern Atlantic tropical wave has its axis along 32W from 
07N to 18N, moving westward at 10-15 kt. The wave is depicted on 
GOES-16 RGB imagery as having a rather broad envelope of broken to
overcast mainly stratocumulus clouds. The GOES-16 RGB images 
along with visible images of the far eastern Atlantic are 
depicting yet another massive plume of Saharan dry air and 
associated dust following in behind the wave from 10N-28N. 

A eastern Caribbean Sea tropical wave has its axis extending from
near 21N59W to 09N62W, moving westward at 15-20 kt. This wave 
continues to be impacted by Saharan dust, which is not allowing 
for any deep convection to develop along and near it. Only 
isolated showers moving quickly westward with the fresh easterly 
trades are seen within about 300 nm east and 180 west of the wave 
axis. This wave will move across the eastern Caribbean Sea through
Tue night, and the central Caribbean Wed through Thu. 

A central Caribbean Sea tropical wave axis is along 79W S of 20N 
to beyond Panama, moving westward around 15 kt. This wave is ill-
defined at the surface. Its position was based on extrapolation 
from the past 6 to 24 hr analyzed position and from the latest 
guidance from 700 mb model diagnostics. No deep convection is 
noted with this wave as it located to the west of an upper level 
trough as mentioned in the above paragraph. 

A Central America tropical wave is along 86W S of 18N, moving 
westward at 10-15 kt. The combination of this wave with local 
topography effects has initiated scattered moderate convection over
much of the central America to include the Gulf of Honduras.  
Model guidance indicates that 700 mb troughing is present over 
much of Central America providing further support for the shower 
and thunderstorm activity. The wave will move into the eastern 
Pacific Ocean on Mon. 


The monsoon trough extends from W Africa near 13N16W to 06N40W.
The ITCZ begins near 06N40W and continues to South America near
05N52W. Scattered moderate convection is from 05N-07N between



High pressure of 1018 mb is the main feature that is influencing 
the synoptic pattern across the basin. Its associated gradient is 
allowing for generally light to moderate anticyclonic flow to 
exist over the gulf waters. Current NWS mosaic radar displays show
scattered showers and isolated thunderstorms over much of the 
eastern gulf waters as well as over the eastern half of the 
central gulf. This activity is moving westward under moderate 
upper northeast winds. The activity should continue into the early
evening, with some possibility of more activity developing during
the overnight hours.

The high pressure will prevail across the northern waters through
Thu. A surface trough will move westward off the Yucatan 
Peninsula each evening through Thu, enhancing nocturnal winds in 
the SW Gulf. 


Please read the Special Features section for details about gale- 
force winds near the coast of Colombia.

Aside from the tropical wave features as described above, an upper
level trough is noted on water vapor imagery to be anchored from 
near eastern Cuba to vicinity Jamaica and to near 10N80W.
Scattered to broken high clouds streaming northeastward are 
seen within 600 nm to its southeast. Isolated showers moving 
rapidly to the west are present over much of the basin, except
along the immediate coasts of Central America S of 16N where
deeper convective activity is occurring as described above 
with the inland tropical wave along 83W. This activity should 
persist through Mon night or so. Otherwise, a tight pressure
gradient will allow for NE-E winds to pulse to minimal gale near 
the coast of Colombia over the next few days as described above
under Special Features. Fresh to strong E winds will continue
over the central Caribbean Sea through the middle of next week.


Please read the Special Features section for details about 
Subtropical Storm Beryl.

A weak 1018 mb low is near 31N78W with a trough extending 
southwestward to near Cape Canaveral, Florida. Recent 
scatterometer data picked up on this feature. Current NWS mosaic 
radar imagery along with recent satellite imagery show increasing 
scattered moderate isolated strong convection within 90 nm of the 
low in the SE and S quadrants. Another surface trough is analyzed 
from near 32N63W to 27N76W near the N Bahamas. The latter surface
trough will slowly weaken through Tue as the upper trough lifts 
to the NE away from it. High pressure will build in the wake of 
the trough. Scattered showers and isolated thunderstorms between 
the Bahamas and southeastern Florida are due to a weak surface. 

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