[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 081735
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
135 PM EDT Sat Sep 8 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 1200 UTC surface analysis and satellite imagery through
1715 UTC.

...SPECIAL FEATURES...

Tropical Storm Florence is centered near 24.5N 54.3W at 08/1500
UTC or 730 nm SE of Bermuda moving W at 6 kt. Estimated minimum
central pressure is 995 mb. Maximum sustained wind speed is 55 kt
with gusts to 65 kt. Scattered moderate convection is from 23N-28N
between 51W-57W. Florence is expected to move over the
southwestern Atlantic Ocean between Bermuda and the Bahamas
Tuesday and Wednesday, and approach the southeastern U.S. coast on
Thursday. Florence is expected to intensify to a hurricane
Sunday, and further intensify to a major hurricane by Tuesday. See
latest NHC forecast/advisory under AWIPS/WMO headers
MIATCPAT1/WTNT31 KNHC for more details.

Tropical Storm Helene is centered near 13.4N 20.6W at 08/1500 UTC
or 230 nm ESE of the Southernmost Cabo Verde Islands moving W at
11 kt. Estimated minimum central pressure is 1001 mb. Maximum
sustained wind speed is 40 kt with gusts to 50 kt. A Tropical
Storm Warning is in effect for the Cabo Verde Islands of
Santiago, Fogo, and Brava. Additional strengthening is forecast
for the next couple of days and Helene is expected to become a
hurricane Sunday or Sunday night. Scattered moderate to isolated
strong convection is from 10N-15N between 18W-26W. See latest NHC
forecast/advisory under AWIPS/WMO headers MIATCPAT3/WTNT33 KNHC
for more details.

Tropical Depression Nine is centered near 14.6N 36.0W at 08/1500
UTC or 1460 nm E of the Windward Islands moving WNW at 5 kt.
Estimated minimum central pressure is 1007 mb. Maximum sustained
wind speed is 30 kt with gusts to 40 kt. Gradual strengthening is
forecast during the next few days, and the depression is expected
to become a tropical storm later today and a hurricane by early
next week. Scattered moderate to isolated strong convection is
from 13N-17N between 34W-40W. See latest NHC forecast/advisory
under AWIPS/WMO headers MIATCPAT4/WTNT34 KNHC for more details.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends west of T.D. Nine from 12N38W to
08N49W. The ITCZ extends from 08N49W to the coast of South
America near 07N58W. Aside from the convection related to tropical
cyclones, scattered moderate convection is from 07N-10N between
34W-42W.

...DISCUSSION...

GULF OF MEXICO...

An upper level low is centered over the SE Gulf of Mexico near
25N86W. A moist and unstable atmosphere over the SE Gulf and
Florida is producing widely scattered moderate convection over
the Straits of Florida from 23N-26N between 80W-85W. Upper level
diffluence is also over the W Gulf producing widely scattered
moderate convection from 22N-24N between 90W-94W. On the surface,
a trough is over the Straits of Florida from 25N80W to 23N84W.

Weak ridging from the Carolinas to the Texas coast
will shift N over the SE United States. Gentle to moderate E to
SE winds and modest seas will prevail through the middle of next
week. The exception will be fresh winds pulsing off west of the
Yucatan peninsula, mainly during the late evening.

CARIBBEAN SEA...

An upper-level trough axis stretches from western Cuba to
northeastern Honduras, and a broad upper level high is centered
over the central Caribbean near 14N74W. Scattered moderate
isolated strong convection is noted west of the upper level high,
roughly south of 16N and west of 74W.

Relatively weak surface ridging over the western Atlantic will
maintain moderate to fresh trade winds over most of the region
into Sun. Building surface high pressure over the eastern Gulf of
Mexico will allow fresh to locally strong E to SE winds and
building seas over portions of the NW Caribbean Sun through Tue.

ATLANTIC OCEAN...

Please see the Special Features section above for details about
T.S. Florence, T.S. Helene, and T.D. Nine.

An upper level low is centered over the W Atlantic near 30N71W.
Widely scattered moderate convection is from 27N-35N between 59W-
69W. A surface trough is over the W Atlantic from 31N75W to S
Florida near 26N81W. Widely scattered moderate convection is W of
75W.

A 1012 mb low is centered over the W Atlantic near 32N68W. A
surface trough extends S from the low to 28N72W. A 1021 mb high is
centered over the central Atlantic near 35N38W.

A weak pressure pattern will support gentle to moderate easterly
winds across the western Atlantic into early next week. Tropical
Storm Florence is forecast by the latest NHC advisory to move
across the northeastern TAFB offshore waters zones Mon through
Tue. Easterly swell well in advance of Florence will propagate
through the open waters east of the Bahamas this weekend.

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

$$
Formosa
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