[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 140547
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
145 AM EDT Fri Sep 14 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
1115 UTC.

...SPECIAL FEATURES...

Hurricane Florence centered near 34.1N 77.2W at 14/0600 UTC or
30 nm E of Wilmington North Carolina moving WNW at 5 kt.
Estimated minimum central pressure is 954 mb. Maximum sustained
wind speed is 80 kt with gusts to 100 kt. Scattered moderate to
strong convection is from 32N-37N between 73W-80W. The present WNW
motion is forecast to continue into Friday. A turn toward the west-
northwest and west at a slow forward speed is expected through
Friday, followed by a slow west-southwestward motion Friday night
and Saturday. On the forecast track, the center of Florence is
expected to move inland across extreme southeastern North Carolina
and extreme eastern South Carolina Friday and Saturday. Florence
will then recurve across the western Carolinas and the central
Appalachian Mountains early next week. Little change in strength is
expected before Florence moves inland on Friday. More significant
weakening is expected over the weekend and into early next week
while Florence moves farther inland. The combination of a dangerous
storm surge and the tide will cause normally dry areas near the
coast to be flooded by rising waters moving inland from the
shoreline. 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 14.9N 64.4W at 14/0300 UTC
or 170 nm S of St. Croix moving W at 14 kt. Estimated minimum
central pressure is 1006 mb. Maximum sustained wind speed is 35 kt
with gusts to 45 kt. Scattered moderate to isolated strong
convection is from 13N-17N between 55W-65W. A westward motion
with a decrease in forward speed is expected for the next few
days. On the forecast track, Isaac will move over the eastern and
central Caribbean Sea during the next few days. Isaac is forecast
to gradually weaken over the next few days, and could degenerate
into a tropical wave at any time. 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.

Tropical Storm Helene centered near 29.7N 36.2W at 14/0600 UTC
or 710 nm SW of Lajes Air Base In The Azores moving N at 18 kt.
Estimated minimum central pressure is 992 mb. Maximum sustained
wind speed is 55 kt with gusts to 65 kt. Scattered moderate to
isolated strong convection is from 21N-27N between 32W-40W. The
cyclone is expected to accelerate and turn toward the northeast
over the weekend. On this forecast track, Helene will be passing
near or over the Azores late Saturday or Sunday. 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.

Tropical Storm Joyce is centered near 32.9N 44.4W at 14/0300 UTC
or 900 nm WSW of the Azores moving SSW at 6 kt. Estimated minimum
central pressure is 1003 mb. Maximum sustained wind speed is 35 kt
with gusts to 45 kt. Isolated moderate convection is from 31N-
37N between 37W-46W. Joyce is moving toward the south-southwest
near 7 mph (11 km/h), and this general motion is expected to
continue tonight. Joyce is forecast to gradually turn toward the
northeast on Friday and then accelerate northeastward over the
weekend. See latest NHC forecast/advisory under AWIPS/WMO headers
MIATCPAT5/WTNT35 KNHC for more details.

An Air Force reconnaissance plane investigating the disturbance in
the western Gulf of Mexico found a broad and elongated area of low
pressure with a few squalls. Isolated moderate convection is from
20N-30N between 90W-100W. Upper-level winds are conducive for
development, and a tropical depression could still form before the
system moves inland along the western Gulf coast on Friday.
Another Air Force reconnaissance plane will investigate the system
on Friday if necessary. Regardless of development, heavy rainfall
and gusty winds are expected across portions of northeastern
Mexico and Texas on Friday and Saturday. There is a medium chance
for tropical cyclone formation within 48 hours. Please read the
latest Tropical Weather Outlook under WMO header ABNT20 KNHC, and
under the AWIPS header MIATWOAT for more details.

...TROPICAL WAVES...

A tropical wave is along 26W, from 06N-20N, moving W at 10 kt.
The wave is supported by well pronounced 700 mb troughing as
depicted in the GFS model guidance. Isolated moderate convection
is between 04N-10N between 22W-31W.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from W Africa near 18N16W to 08N26W to
09N40W. The ITCZ continues from 09N40W to 10N50W to 14N57W. Aside
from the convection associated with the tropical wave along 26W,
scattered moderate convection is from 03N-08N between 11W-18W.

...DISCUSSION...

GULF OF MEXICO...

Please read the SPECIAL FEATURES section for details about an
area of disturbed weather that is in the western Gulf of Mexico.
An upper-level low is over the NE Gulf near 29N83W. Widely
scattered moderate convection is over the far NE Gulf of Mexico
and Florida.

A dissipating stationary front is located along the Texas and SW
Louisiana coasts with scattered showers and isolated moderate
thunderstorms.

CARIBBEAN SEA...

Please read the SPECIAL FEATURES section for details about
Tropical Storm Isaac.

The eastern extent of the eastern Pacific monsoon trough passes
through Costa Rica and Panama along 09N. Scattered moderate
convection is S of 11N.

An large upper level low is in the western Caribbean Sea near
18N80W. Isolated weak convection is between 13N-20N between 78W-
83W.

An an upper level high is centered in the NE Caribbean Sea near
19N69W, producing a good amount of shear over T.S. Isaac.

ATLANTIC OCEAN...

Please read the SPECIAL FEATURES section, for details about
Hurricane Florence, Tropical Storm Helene, and Subtropical Storm
Joyce.

No other significant features are noted in the Atlantic other than
the features mentioned above.

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

$$
Formosa
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