[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 091211
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
811 AM EDT Sun Sep 9 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.

...SPECIAL FEATURES...

Tropical Storm Florence is centered near 24.5N 55.8W at 09/0900
UTC or 660 nm SE of Bermuda moving W at 5 kt. Estimated minimum
central pressure is 989 mb. Maximum sustained wind speed is 60 kt
with gusts to 75 kt. Florence will 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 become a hurricane today and rapid
intensification is likely to begin by tonight. Florence is
forecast to become a major hurricane on Monday. Scattered moderate
to isolated strong convection is from 22N-26N between 54W-58W.
See latest NHC Public Advisories issued under WMO header WTNT31
KNHC and under AWIPS header MIATCPAT1. Forecast/Advisories are
issued under WMO header WTNT21 KNHC and under AWIPS header
MIATCMAT1.

Tropical Storm Isaac is centered near 14.5N 38.1W at 09/0900 UTC
or 1340 nm E of the Windward Islands moving W at 8 kt. Estimated
minimum central pressure is 1001 mb. Maximum sustained wind speed
is 45 kt with gusts to 55 kt. Strengthening is forecast during the
next few days, and Isaac is expected to become a hurricane by
Monday. Scattered moderate to isolated strong convection is from
11N-16N between 36W-42W. Public Advisories for Tropical Storm
Isaac are issued under WMO header WTNT34 KNHC and under AWIPS
header MIATCPAT4. Forecast/Advisories for Tropical Storm Isaac are
issued under WMO header WTNT24 KNHC and under AWIPS header
MIATCMAT4.

Tropical Storm Helene is centered near 13.2N 24.0W at 09/0900 UTC
or 100 nm SSE of the Southernmost Cabo Verde Islands moving W at
12 kt. Estimated minimum central pressure is 997 mb. Maximum
sustained wind speed is 55 kt with gusts to 65 kt. A Tropical
Storm Warning is in effect for the Cabo Verde islands of
Santiago, Fogo, and Brava. Additional strengthening is forecast
during the next couple of days, and Helene is expected to become
a hurricane later today. Scattered moderate to isolated strong
convection is from 10N-17N between 19W-27W. Public Advisories for
Tropical Storm Helene are issued under WMO header WTNT33 KNHC and
under AWIPS header MIATCPAT3. Forecast/Advisories for Tropical
Storm Helene are issued under WMO header WTNT23 KNHC and under
AWIPS header MIATCMAT3.

...TROPICAL WAVES...

A tropical wave is along 83W from W Cuba at 21N southward. This
wave has a complex past history, and it is likely that it may have
been related to T.S. Florence from several days ago. Scattered
moderate to strong convection is from 13N-22N between 78W-85W.

...MONSOON TROUGH/ITCZ...

The ITCZ is W of T.S. Isaac from 09N42W to the coast of South
America near 08N59W. Scattered moderate convection is from 07N-09N
between 30W-47W.

...DISCUSSION...

GULF OF MEXICO...

An upper level low is centered over the E Gulf of Mexico near
24N88W. Scattered showers are E of 89W. An upper level ridge is
over the W Gulf W of 92W with northerly upper level flow.
Scattered showers are along the Texas coast. At the surface, 5-10
southerly flow covers the Gulf.

A weak surface ridge from the Carolinas to the Texas coast will
shift northward in order to cover the SE United States. Gentle to
moderate E to SE winds and modest seas will prevail through the
middle of the next week. The exception will be fresh winds
developing off the west coast of the Yucatan peninsula, mainly
during the late evening.

CARIBBEAN SEA...

A large upper level high is centered over the central Caribbean
near 16N75W. The tropical wave is main source of convection in the
Caribbean. See above.

Isaac is forecast to approach the Lesser Antilles Wed evening,
and continue into the eastern Caribbean Thu. A relatively weak
surface ridge in the western Atlantic Ocean will maintain moderate
to fresh trade winds over most of rest of the region through
Monday night. Building high pressure in the eastern Gulf of Mexico
will allow fresh to locally strong E to SE winds and building
seas in parts of the NW Caribbean Sea from Sunday through Tuesday.

ATLANTIC OCEAN...

Please read the SPECIAL FEATURES section for details about
T.S. Florence, T.S. Isaac, and T.S. Helene.

Isolated moderate convection is over the W Atlantic from 25N-30N
between 74W-80W. A small upper level low is near 30N70W. A 1014
mb low pressure center is near 31N68W. A 1025 mb high is over the
E Atlantic near 34N27W.

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

$$
Formosa
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