[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 231201
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
801 AM EDT Thu Aug 23 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 0600 UTC surface analysis and satellite imagery through
1115 UTC.

...TROPICAL WAVES...

A far eastern Atlantic tropical wave has its axis along 30W from
07N-20N, moving westward at 10-15 kt. The wave is embedded within
a very dry and stable environment which is inhibiting convection
at this time.

A central Atlantic tropical wave has its axis extending along 51W
from 06N-20N, moving westward at 10-15 kt. This wave is also
embedded within a very dry and stable environment caused by
Saharan Air Layer outbreak of the past several days that is
spreading westward across the central and eastern Atlantic.
Scattered showers are noted south of 10N where the wave meets the
monsoon trough.

An eastern Caribbean Sea tropical wave has its axis along 71W
south of 20N to well inland Venezuela. It is moving westward at
10-15 kt. No significant convection is observed within this wave
at this time.

A west Caribbean tropical wave has its axis along 85W from 05N-
20N, moving westward near 10-15 kt. Scattered showers are within
120 nm of the wave axis.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis extends from the African coast near
14N17W to 08N33W to 10N40W to 09N52W. The ITCZ axis begins at
09N52W and continues to the coast of South America near 07N59W.
Widely scattered moderate convection is from 05N-09N between
15W-21W. Scattered showers are noted elsewhere within 120 nm
either side of the monsoon trough and ITCZ.

...DISCUSSION...

GULF OF MEXICO...

A cold front is over the N Gulf of Mexico from 31N82W to 27N90W to
29N95W. A pre-frontal trough extends from N Florida near 30N81W to
the NE Gulf near 26N87W. widely scattered moderate convection is
within 90 nm of the pre-frontal trough. Elsewhere, scattered
moderate convection is over the Bay of Campeche from 17N-20N
between 93W-96W. The present pressure gradient across the gulf
supports light winds throughout, with a windshift along the
frontal system. In the upper levels an upper level high centered
over Texas near 32N99W is producing NE upper level winds over the
Gulf with upper level moisture. Expect for the front to become
quasi-stationary until Fri and dissipate on Sat.

CARIBBEAN SEA...

Two tropical waves are moving across the basin. Refer to the
section above for details. An upper level trough extends from
eastern Cuba southwestward to just east of northeastern Honduras.
Water vapor imagery indicates plentiful moisture along and to the
northwest of this trough, and it is where scattered showers are
occurring. Scattered showers are also occurring over the southwestern
Caribbean south of 12N between 80W-85W due to the interaction of a
tropical wave, low-level wind speed convergence, and the eastern
segment of the eastern Pacific monsoon trough that stretches east-
northeastward to the far southwestern Caribbean along 09N.

A slighter tighter pressure gradient behind the tropical wave
along 82W will help induce strong to near gale force northeast to
east trade winds over the south-central Caribbean waters off the
coast of Colombia and across the Gulf of Venezuela overnight. The
strong trades are forecast to reach northward to 15N. Moderate to
fresh trades will continue elsewhere through Fri, as little
overall changes are expected with the present synoptic set-up
through that period.

ATLANTIC OCEAN...

Two tropical waves are moving across the basin. Refer to the
section above for details. A surface trough is analyzed over the W
Atlantic from 29N67W to 24N71W. Scattered showers are within 180
nm of the trough. Another trough extends over the central Atlantic
from 29N56W to 20N57W. Scattered showwers are within 120 nm of the
trough. A 1024 mb high is analyzed north near 36N53W. Saharan
dust and associated dry air, although not as dense as in previous
days, is noted mainly east of about 60W on GOES-16 GEO color dust
imagery. The dust is keeping convection limited to non- existent
across the eastern and central Atlantic waters.

For additional information please visit
http://www.hurricanes.gov/marine

$$
Formosa
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