Atlantic Tropical Weather Discussion (Text)

AXNT20 KNHC 171800

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
205 PM EDT Tue Oct 17 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 1200 UTC surface analysis and satellite imagery through 
1715 UTC.


A cold front extends from central Florida to the Bay of Campeche 
in the SW Gulf. Strong high pressure west of the front supports 
30-35 kt northerly winds south of 21N west of 95W. The front is 
expected to gradually weaken through Wednesday night with winds 
decreasing below gale force tonight. See the latest NWS High 
Seas Forecast under AWIPS/WMO headers MIAHSFAT2/Vicinity KNHC for 
more details.


A tropical wave south of 13N along 54W is moving W at 10-15 kt. 
The wave coincides with troughing at 700 mb troughing and a 
maximum in 850 mb relative vorticity. Scattered moderate 
convection is from 08N-10N between 53W-57W.

A tropical wave south of 16N along 64W is moving W at 10-15 kt. 
The wave coincides with troughing at 700 mb troughing and a 
maximum in 850 mb relative vorticity. Widely scattered moderate 
convection is from 12N-15N between 61W-64W.

A tropical wave south of 16N along 80W is moving W at 10-15 kt. 
The wave coincides with broad 700 mb troughing between 75W-82W. 
Scattered moderate to strong convection is west of the wave 
axis from 09N-13N between 80W-84W.


The convergence zone continues to sag equatorward. The African 
monsoon trough extends from 09N13W to 08N25W. The ITCZ axis 
continues from 08N25W to 07N53W. Scattered moderate convection 
is from 06N-10N between 37W-47W..



The cold front mentioned above is supported aloft by an upper 
level trough pushing into the north-central Gulf. Scattered 
showers are occurring within 150 nm south and east of the front. 
It will become nearly stationary overnight then gradually become 
diffuse through Wednesday night. Fresh to strong N-NE winds will 
prevail behind the front through early Wednesday and then weaken 
through Thursday. Surface ridging is expected to remain in place 
across the basin the rest of the week.


Two low amplitude tropical waves are moving across the basin 
with scattered convection. See above. A nearly stationary 1007 
mb low is centered near 10N76W, and the eastern extension of the 
Pacific monsoon trough is analyzed from 11N69W to 11N75W to 
09N78W. An upper level anticyclone centered over the W Caribbean 
near 16N80W supports mostly dry air aloft across the region. 
Scatterometer data shows fresh E-SE winds in the eastern 
Caribbean, and gentle to moderate E-NE winds west of 75W. 
Moderate to fresh trades are expected to persist across the 
basin through Wednesday.


A disorganized line of showers is slowly moving over the middle 
of the island. Local sea breeze dynamics during afternoon and 
evening hours is expected to initiate showers and tstms across 
the island today. A tropical wave will move south of Hispaniola 
Wednesday and Thursday, increasing the potential for convection.


A cold front extends across the NW portion of the SW North Atlc 
from 32N74W to central Florida. Scattered showers are occurring 
within 180 nm NW of the front. A surface trough extends from a 
low near 34N67W to 24N73W. Scattered moderate isolated strong 
showers are well east of the trough within 90 nm either side of 
a line from 32N65W to 22N68W. A broad ridge anchored by high 
pressure centered near 33N37W dominates the remainder of the 
tropical north Atlantic, north of 10N and east of 65W.

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Page last modified: Tuesday, 17-Oct-2017 18:00:34 UTC