[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 052357
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
757 PM EDT Thu Sep 5 2019

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
2320 UTC.

...SPECIAL FEATURES...

Hurricane Dorian is centered near 33.1N 78.5W at 05/2100 UTC or
40 nm SSE of Myrtle Beach, South Carolina and about 70 nm SSW of
Wilmington, NC. Dorian is moving NE at 7 kt with a minimum central
pressure of 960 mb. The maximum sustained wind speed is 90 kt
with gusts to 110 kt. Numerous moderate with embedded scattered
strong convection is seen within 150 nm N semicircle and 80 nm S
semicircle. Scattered moderate to isolated strong convection is
seen elsewhere within 300 nm NE quad, 160 nm SE quad, 150 nm SW
quad, 200 nm NW quad. Currently, the eye of Dorian is still just
off the North and South Carolina coast and approaching Bald Head
Island, NC. Dorian will increase in forward speed through
Saturday. It is expected to move near or over the coast of North
Carolina tonight and Friday. The center should move to the
southeast of extreme southeastern New England Friday night and
Saturday morning, and approach Nova Scotia later Saturday or
Saturday night. Slow weakening is expected during the next few
days. However, Dorian is expected to remain a powerful hurricane
as the center moves near the coasts of South and North Carolina.
Dorian is forecast to become a hurricane-force post-tropical
cyclone by Saturday night as it approaches Nova Scotia. See the
latest NHC forecast/advisory under AWIPS/WMO headers
MIATCMAT5/WTNT25 KNHC or the website hurricanes.gov for more
details.

Tropical Storm Gabrielle is centered near 23.4N 35.9W at 05/2100
UTC or 800 nm NW of the Cabo Verde Islands and about 990 nm SSW of
the Azores. Gabrielle is moving NW at 9 kt with an estimated
minimum central pressure of 1002 mb. The maximum sustained wind
speed is 40 kt with gusts to 50 kt. Scattered moderate convection
is seen on the north side only, from 26N-30N between 31W-37W.
A faster motion toward the northwest is expected for the next
several days. Little change in strength will likely occur during
the next day or two. Slow strengthening is forecast to occur over
the weekend. See latest NHC forecast/advisory under AWIPS/WMO
headers MIATCMAT3/WTNT23 KNHC or the website hurricanes.gov for
more details.

...TROPICAL WAVES...

An eastern Atlantic tropical wave extends its axis along 21W S of
19N, moving W at 10-15 kt. Scattered moderate showers with
embedded thunderstorms are seen from 13N-16N between 22W-24W.
Gradual development of this system is possible and a tropical
depression could form while it moves westward across the tropical
Atlantic Ocean through early next week. Enhanced rainfall is
possible across the Cabo Verde Islands through early Friday as the
disturbance moves through the region. The chance of tropical
cyclone formation during the next 48 hours is low.

An Atlantic tropical wave extends its axis along 58W S of 20N,
moving W at 10-15 kt. It was not discernible on the 1800 UTC map
but based on model data and surface features it will be added on
the 0000 UTC map. Scattered showers are located about 200 nm
within Leeward Islands from 15N- 21N between 51W- 57W. Only slow
development of this disturbance, if any, is expected during the
next couple of days while it moves slowly northwestward. The
chance of tropical cyclone formation during the next 48 hours is
low.

A central Caribbean tropical wave extends its axis along 70W S of
17N, moving W at 15 kt. Scattered moderate to strong convection
continues to be noted over W Venezuela and E Colombia from 08N-
12N between 68W-74W. Scattered showers are also seen over eastern
portions of the ABC Islands.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from the coast of Mauritania near 19N16W
to 10N26W to 11N47W. The ITCZ is from 11N52W to 13N63W. Aside
from the convection mentioned in the section above, scattered
moderate showers with isolated thunderstorms are seen from 04N-
12N between 25W- 48W. Isolated showers and thunderstorms are seen
along the ITCZ 09N-12N between 51W-59W.

GULF OF MEXICO...

Scattered showers and thunderstorms are seen in the central and
western Gulf of Mexico from 23N-27N and west of 85W. Otherwise,
drier air is over the northern Gulf of Mexico, with a 1018 mb
surface high centered near 28N94W. The latest ASCAT pass shows
moderate W winds over the far NE Gulf of Mexico, with gentle winds
elsewhere in the basin.

High pres will extend from NW to SE across the basin producing
gentle to moderate winds through the weekend, then will extend
from E to W from the NE Gulf early next week allowing for return
flow and a slight increase in winds.

CARIBBEAN SEA...

Refer to the section above for details on the tropical waves
moving across the basin.

An upper-level trough over the western Caribbean is aiding in
scattered moderate convection across this area from 82W-86W
between 79W-86W. Some isolated thunderstorms are moving off of SW
Puerto Rico into adjacent waters. Otherwise, fair weather prevails
in the central and eastern Caribbean due to upper level ridging.
The latest ASCAT pass shows strong trades in the south-central
Caribbean from 11N-15N between 73.5W-77W. Otherwise, moderate to
fresh trades are in the central Caribbean with light to gentle
trades elsewhere.

Weak Atlantic ridge extends from the central Atlantic to the
SE Bahamas. Fresh to strong tradewinds will pulse in the S
central Caribbean tonight into early Friday, and then again early
next week. Otherwise, mainly moderate to fresh tradewinds are
expected.

ATLANTIC OCEAN...

Refer to the sections above for details on Dorian, Gabrielle and
two tropical waves moving across the basin.

Scattered showers are still moving across the western Atlantic, N
of 29N and W of 76W. Isolated thunderstorms are seen moving off
of Cuba and into the northern Bahamas. Scattered showers and
thunderstorms are moving south into the central Atlantic due to a
small area of low pressure located a few hundred miles northeast
of Bermuda. This activity is noted N of 26N between 56W-65W. A
trough is extending from the low near 35N60W to 28N63W. This
system has become poorly defined and significant development is
not anticipated.

An upper level low is seen in the central Atlantic with a surface
trough analyzed from 23N41W to 27N47W. Scattered showers and
thunderstorms are associated with this trough from 24N-30N
between 43W-48W. Another surface trough is noted 200 nm east of
the Lesser Antilles, analyzed from 16N57W to 22N55W. Scattered
showers and thunderstorms are seen from 16N-23N between 49W-57W.

Hurricane Dorian will produce large northerly swell over the SW N
Atlantic through the weekend. This swell continues to produce
high seas within the Gulfstream offshore of central and SE
Florida. Much more tranquil marine conditions are forecast by
early next week.

$$
AKR
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