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Atlantic Tropical Weather Discussion

AXNT20 KNHC 171029

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Mon May 17 2021

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 31N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 0600 UTC surface analysis and satellite imagery through 
0930 UTC.



A 1003 mb low pressure center is located near 32N57W, just to the
north of the area, and moving E-NE near 20 kt. Overnight ASCAT
data shortly after 0000 UTC showed SW winds of 30-40 kt across the
south semicircle of this low, that extended to 30N. Expect these 
gale-force SW to W winds to move along the northern boundary of
the area between 55W and 58W through 1200 UTC before winds
diminish to 25-30 kt there. Seas of , and sea heights ranging 
from 10 feet to 13 feet should be expected across this area.


The surface pressure gradient, that is between  high pressure 
that is between the Madeira Archipelago and the Azores Islands, 
and comparatively lower surface pressures in West Africa, will 
support developing gale-force winds in the METEO-FRANCE forecast 
area, that is called AGADIR. The gale-force winds are forecast to 
start at 17/1500 UTC, and end possibly at 18/0000 UTC. Seas are 
forecast to range from 9 to 12 feet. Please, refer to the Meteo-
France High Seas Forecast, that is on the website: previsions-meteo- 
marine/bulletin/grandlarge/metarea2, or the website: 
19193337429.html, for more details.


The monsoon trough passes through the coastal plains of 
Guinea_Bissau near 11N15W to 06N20W. The ITCZ continues from 
06N20W to 03N30W, to the Equator along 37W to the mouth of the 
Amazon River basin near 01S48W. Scattered moderate to strong 
convection is noted from 01N to 07N between 02W and 28W. Scattered
moderate isolated strong convection is noted within 180 nm N of 
the ITCZ between 30W and 51W.


High pressure across the NE U.S. extends S-SW into the NE Gulf
this morning, and supports moderate to fresh E to SE winds across
the basin. This return flow across the NW Gulf is transporting
abundant low level moisture into Texas, where a middle level 
trough is moving eastward across the state. Scattered strong 
thunderstorms have moved across SE Texas and are moving across SW 
Louisiana and the adjacent coastal waters north of 29N. This 
weather is expected to shift eastward today. Elsewhere upper level
ridging and generally fair weather prevails across the basin.

High pressure extending into the NE Gulf will remain generally 
stationary throughout the week. This will support moderate to 
fresh E to SE winds over the basin through Tue. Winds will 
increase to fresh to strong late Tue through Fri as low pressure 
deepens across the Southern Plains. 


Atlantic high pressure is centered across the NE Atlantic and
extends W-SW and weakly across the W Atlantic north of the area.
This is producing a modest pressure gradient, and supporting fresh
to locally strong tradewinds across the southern Caribbean south 
of 15N between 64W and 77W, where seas are 5 to 7 ft. Stable 
atmospheric conditions associated with the western side of an 
upper level trough continue to produce generally fair weather 
east of 80W. A low to mid level trough to the south of 13N is 
moving across the Windward Islands this morning and will bring 
tropical moisture with scattered showers and a few thunderstorms 
across the SE Caribbean today and tonight.

The monsoon trough passes through Colombia near 11N74W across 
Panama and into the eastern Pacific Ocean. Scattered moderate
convection is noted south of 10N across the Gulf of Uraba and
adjacent waters of Panama east of 79W. 

Atlc high pressure ridge NE of the area will shift eastward and
weaken, diminishing winds and seas modestly across the basin through
Wed. Trade winds will increase basin wide Wed night through Fri 
night as high pressure builds across the W Atlc. 


A cold front extends from the low pressure near 32N57W through
31N54w to 25N60W into the southern Bahamas, where it's remnants
become a shearline across eastern Cuba. Scattered moderate
convection is noted within 60 nm southeast of the front to the
east of 60W, while scattered showers are seen elsewhere within 180
nm either side of the front to Cuba. Beyond the gale force SW
winds mentioned above, W to SW winds of 20-30 kt prevail elsewhere
south of the low to 27N between 50W and 60W. Seas across this area
are 8 to 13 ft. To the NW of the front, moderate NE winds prevail
within 240 nm north of the front and through the Bahamas and
Straits of Florida, with gentle NE to E winds farther north.

A surface ridge extends from a 1023 mb high pressure center near 
34N22W to the waters north of Hispaniola. The pressure gradient to
the south of the ridge is producing moderate to fresh tradewinds
to the south of 19N, where seas are 5 to 7 ft.

The weakening frontal boundary will drift SE and dissipate 
through late Tue. NE to E winds will become fresh to strong north
of 23N and west of 68W late Tue through Fri as high pressure 
builds across the W Atlc. Seas will build 7 to 11 ft during this
time to produce very rough marine conditions.