Tropical Weather Discussion
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AXNT20 KNHC 172349

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
749 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 1800 UTC surface analysis and satellite imagery through
2345 UTC.


A frontal boundary extends from central Florida to the Bay of
Campeche in the SW Gulf. Strong high pressure west of the front
supports gale-force 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/KNHC for
more details.


A tropical wave extends its axis from 14N56W to 07N57W, moving
west 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 07N-13N between 54W-60W.

A tropical wave is moving across the eastern Caribbean extending
its axis from 16N64W to 07N64W, moving west at 10-15 kt. The wave
coincides with troughing at 700 mb troughing and a maximum in 850
mb relative vorticity. At this time, no significant convection is
related to this feature.

A tropical wave is over the western Caribbean with axis from
16N81W to 04N81W, moving west at 10-15 kt. The wave coincides
with broad 700 mb troughing west of 80W. Scattered moderate to
strong convection is south of 15N and west of 80W.


The African monsoon trough extends from 09N14W to 08N25W. The
ITCZ continues from 08N25W to 07N52W. Scattered moderate
convection is from 06N-10N between 37W-50W.



The frontal boundary mentioned in the section above is supported
aloft by an upper-level trough pushing into the north-central
Gulf. Scattered showers are occurring along and southeast of the
front. As of 1800 UTC, the front was analyzed as a cold front over
the eastern Gulf along 26N to 85W, then stationary from that point
to 24N92W to 18N94W. The front will gradually become diffuse
through Wednesday night. Fresh to strong northerly 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 through the rest of the week.


Two low amplitude tropical waves are moving across the basin
See the section above for details. The eastern extension of the
Pacific monsoon trough is analyzed from 10N83W to 09N76W. An
upper-level anticyclone centered over the west Caribbean near
16N81W supports mostly dry air aloft across the region.
Scatterometer data shows fresh easterly winds in the eastern
Caribbean, and gentle to moderate easterly winds west of 75W.


A line of showers is slowly moving over the southwestern portion
of the island. This activity will dissipate overnight. A tropical
wave will move south of the island by Wednesday and Thursday,
increasing the potential for convection.


A cold front extends across the western Atlantic from 32N70W to
central Florida. Scattered showers are occurring within 180 nm
to the north of the front. To the east, a surface trough extends
from a low near 33N67W to 24N72W. This feature is the reflection
of an upper-level trough. Scattered showers are within 240 nm of
the trough. Another surface trough extends from 31N42W to 22N46W. A
broad ridge anchored by 1030 mb high pressure centered near
33N38W dominates the remainder of the basin.

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