[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 120532
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
132 AM EDT Wed Sep 12 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 0000 UTC surface analysis and satellite imagery through
0515 UTC.

...SPECIAL FEATURES...

Hurricane Florence is centered near 28.4N 68.7W at 12/0300 UTC or
310 nm SW of Bermuda moving WNW at 15 kt. Estimated minimum
central pressure is 946 mb. Maximum sustained wind speed is 120
kt with gusts to 145 kt. Latest satellite imagery shows numerous
strong convection near the center from 27N-30N between 65W-69W.
Scattered moderate to isolated stromg convection is elsewhere from
25N-31N between 64W-71W. A motion toward the west-northwest and
northwest is expected through early Thursday. Florence is expected
to slow down considerably by late Thursday into Friday. On the
forecast track, the center of Florence will move over the
southwestern Atlantic Ocean between Bermuda and the Bahamas
through Wednesday, and approach the coast of North Carolina or
South Carolina in the hurricane warning area on Thursday and
Friday. Florence is a category 4 hurricane on the Saffir-Simpson
Hurricane Wind Scale. Further strengthening is forecast through
Wednesday. While some weakening is expected on Thursday, Florence
is forecast to be an extremely dangerous major hurricane through
landfall. Public Advisories for Florence are issued under WMO
header WTNT31 KNHC and under AWIPS header MIATCPAT1.
Forecast/Advisories for Florence are issued under WMO header
WTNT21 KNHC and under AWIPS header MIATCMAT1.

Tropical Storm Isaac is centered near 14.5N 52.3W at 12/0300 UTC
or 500 nm E of Martinique moving W at 14 kt. Estimated minimum
central pressure is 999 mb. Maximum sustained wind speed is 55 kt
with gusts to 65 kt. Latest satellite imagery shows numerous
strong convection 13N-16N between 49W-51W. Scattered moderate
convection is elsewhere from 12N-18N between 48W-52W. Isaac is
anticipated to move near or over the central Lesser Antilles on
Thursday, move into the eastern Caribbean Sea Thursday night, and
move into the central Caribbean Sea by Friday or Saturday. Gradual
weakening is forecast during the next few days. Public Advisories
for Isaac are issued under WMO header WTNT34 KNHC and under AWIPS
header MIATCPAT4. Forecast/ Advisories for Isaac are issued under
WMO header WTNT24 KNHC and under AWIPS header MIATCMAT4.

Hurricane Helene centered near 18.0N 35.4W at 12/0300 UTC or 660
nm WNW of the Cabo Verde Islands moving NW at 9 kt. Estimated
minimum central pressure is 973 mb. Maximum sustained wind speed
is 85 kt with gusts to 105 kt. Latest satellite imagery shows
scattered moderate to strong convection from 15N-22N between 32W-
37W. Helene is forecast to turn toward the north Thursday. Helene
is forecast to accelerate and turn toward the northeast by the
end of the week.  Gradual weakening is likely over the next couple
of days, and Helene is expected to become a tropical storm by
Thursday. Public Advisories for Helene are issued under WMO header
WTNT33 KNHC and under AWIPS header MIATCPAT3. Forecast/Advisories
for Helene are issued under WMO header WTNT23 KNHC and under
AWIPS header MIATCMAT3.

An area of disturbed weather located over the extreme northwestern
Caribbean Sea and the southeastern Gulf of Mexico continues to show
some signs of organization.  Upper-levels winds are forecast to
become more conducive for development, and a tropical depression is
likely to form by Thursday night while the disturbance moves across
the western Gulf of Mexico.  If necessary, an Air Force
reconnaissance plane will investigate the system tomorrow.
Interests across northeastern Mexico and the coasts of Texas and
Louisiana should monitor the progress of this system.  Regardless of
development, heavy rainfall and gusty winds are expected to continue
over western Cuba and portions of the northeastern Yucatan Peninsula
through tonight.

An area of disturbed weather located over the extreme
northwestern Caribbean Sea and the southeastern Gulf of Mexico
continues to show some signs of organization. Upper-levels winds
are forecast to become more conducive for development, and a
tropical depression is likely to form by Thursday night while the
disturbance moves across the western Gulf of Mexico. If necessary,
an Air Force reconnaissance plane will investigate the system
tomorrow. Interests across northeastern Mexico and the coasts of
Texas and Louisiana should monitor the progress of this system.
Regardless of development, heavy rainfall and gusty winds are
expected to continue over western Cuba and portions of the
northeastern Yucatan Peninsula through tonight. This area of
disturbed weather has a medium chance for tropical cyclone
formation over the next couple of days. Please read the latest
Tropical Weather Outlook under WMO header ABNT20 KNHC, and under
the AWIPS header MIATWOAT for more details on this evolving
system.

...TROPICAL WAVES...

A Tropical wave is along the coast of W Africa along 17W south of
18N, moving W at 15Kt. A distinct 700 mb trough is noted. Widely
scattered moderate convection is observed along the coast of W
Africa from 08N-20N between 12W-22W.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from W Africa near 11N15W to 06N17W to
04N22W. Isolated moderate convection is from 03N-06N between
16W-22W.

...DISCUSSION...

GULF OF MEXICO...

See Special Features above for details on an area of disturbed
weather over the southeastern Gulf of Mexico. A surface trough
extends from the SE Gulf of Mexico near 27N87W to the Yucatan
Peninsula near 18N90W. A 1010 mb low is embedded on the trough
near 23N88W. Isolated moderate convection is within 120 nm of the
trough. Elsewhere, isolated moderate convection is over the
Florida Peninsula.

In the upper levels, an upper level low is also centered near
23N89W drifting W. Upper level diffluence is noted inland over S
Mexico producing scattered moderate to isolated strong convection
S of 22N.

CARIBBEAN SEA...

Widely scattered moderate convection is over the NW Caribbean and
Central America W of 85W. Elsewhere, scattered moderate convection
is over S Haiti. The eastern extent of the E Pacific monsoon
trough is over Costa Rica and Panama along 09N. Scattered moderate
convection is within 120 nm S of the monsoon trough. A 1008 mb low
is centered over N Colombia near 09N74W.

In the upper levels, an upper level low is centered over N
Colombia near 12N73W. An upper level high is centered just E of
the Leeward Islands near 16N59W.

Expect Isaac to enter the Caribbean Sea on Thursday.

ATLANTIC OCEAN...

Please refer to the Special Features section above for details
on Hurricanes Florence and Helene and on Tropical Storm Isaac.

Scattered showers are over the central Atlantic N of 29N between
40W-50W due to a cold front N of the area.

In the upper levels, a small upper level low is centered N of the
Bahamas near 29N78W. Scattered showers are over the N Bahamas.

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

$$
Formosa
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