[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 100531
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
131 AM EDT Mon Sep 10 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...

The center of Hurricane Florence at 10/0300 UTC is near 24.6N
57.7W. Florence is moving W, or 280 degrees, 06 knots. The
estimated minimum central pressure is 974 mb. The maximum
sustained wind speeds are 80 knots with gusts to 100 knots.
Scattered moderate to strong rainshowers are within 30 nm of the
center everywhere. Numerous strong rainshowers are within 90 nm
of the center in the NW semicircle. Scattered moderate to isolated
strong rainshowers are elsewhere from 21N to 28N between 54W and
62W. 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.

The center of Hurricane Isaac at 10/0300 UTC is near 14.5N 41.6W.
Isaac is moving W, or 275 degrees, 12 knots. The estimated
minimum central pressure is 993 mb. The maximum sustained wind
speeds are 65 knots with gusts to 80 knots. Numerous strong
rainshowers are within 75 nm of the center in the W semicircle,
and within 45 nm of the center in the E semicircle. Scattered
moderate to strong rainshowers are from 12N to 14N between 41W and
44W. Anyone who is in the area of the Lesser Antilles should
monitor the progress of Hurricane Isaac. 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.

The center of Hurricane Helene at 10/0300 UTC is near 13.9N 27.2W.
Helene is moving WNW, or 285 degrees, 11 knots. The estimated
minimum central pressure is 984 mb. The maximum sustained wind
speeds are 75 knots with gusts to 90 kt. Numerous strong
rainshowers are within 135 nm of the center in the NW quadrant and
in the SW quadrant. Widely scattered moderate to isolated strong
rainshowers are elsewhere from 09N to 17N between 22W and 31W.
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 WAVES...

A tropical wave is along 90W/91W from 21N southward, along the
western side of the Yucatan Peninsula of Mexico, into the eastern
Pacific Ocean. Isolated moderate to locally strong rainshowers are
inland in Mexico, in the Isthmus of Tehuantepec of southern
Mexico, between 90W and 95W.

...MONSOON TROUGH/ITCZ...

The monsoon trough is inland in Africa. The ITCZ is along 08N48W
06N54W 07N58W. Isolated moderate to locally strong rainshowers
are elsewhere from 10N southward from 20W eastward, and to the
south of Hurricane Isaac and Hurricane Helene from 06N to 10N
between 34W and 45W. Rainshowers are possible elsewhere from 10N
southward from 60W eastward.

...DISCUSSION...

GULF OF MEXICO...

An upper level trough extends from the NE corner of the Gulf of
Mexico, to a 26N87W cyclonic circulation center, into the SW
corner of the Gulf of Mexico, just to the north of the Isthmus of
Tehuantepec of southern Mexico. Upper level cyclonic wind flow
covers the Gulf of Mexico and surrounding coastal plains to the
east of the line that runs from coastal Alabama, to 26N92W, to the
coast of Mexico near 20N92W. Isolated moderate rainshowers are in
the area of upper level cyclonic wind flow. f

A weak surface ridge in the SE U.S.A. generally will maintain
light to moderate wind speeds in the basin through Friday night.
A surface trough will move westward, off the coast of the
Yucatan Peninsula each evening, and it will dissipate in the
SW Gulf of Mexico each morning. The trough will be accompanied by
moderate to fresh winds.

CARIBBEAN SEA...

Upper level cyclonic wind flow covers the Caribbean Sea to the NW
of the line that runs from NW Cuba to the Gulf of Honduras.
Scattered strong rainshowers are from 15N to 17N between 80W and
84W. Isolated moderate rainshowers are elsewhere to the NW of the
line that runs from the Mona Passage to the east central coast of
Nicaragua.

The monsoon trough is along 09N74W in northern Colombia, beyond
10N in NW Costa Rica. Scattered strong rainshowers in clusters are
from 09N to 11N between Colombia and 77W.

Newly upgraded Hurricane Isaac near 14.5N 41.6W 997 mb at 11 PM
EDT moving W at 12 kt. Maximum sustained winds 65 kt gusts 80 kt.
Isaac will move to 14.9N 46.3W on Monday evening, to 14.9N 48.0W
on Tuesday morning, to 15.0N 52.0W on Tuesday evening, and to
15.2N 57.3W on Wednesday evening. Isaac will weaken to a tropical
storm near 15.5N 63.5W on Thursday evening, and continue to
weaken as it moves to the central Caribbean Sea near 15.5N 70.0W
on Friday. A relatively weak surface ridge in the western
Atlantic Ocean will maintain moderate to fresh trade winds in
most of the region through Monday night.

ATLANTIC OCEAN...

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

An upper level cyclonic circulation center is near 29N70W. A
surface trough is along 36N61W 34N62W 31N64W. Upper level cyclonic
wind flow also is from 30N northward from 77W westward. Isolated
moderate rainshowers are from 26N northward from 69W westward.

Hurricane Florence near 24.6N 57.7W 974 mb at 11 PM EDT moving W
at 6 kt. Maximum sustained winds 80 kt gusts 100 kt. Florence will
move to 24.9N 59.1W Monday morning, 25.6N 61.5W Monday evening,
26.5N 64.4W Tuesday morning, 27.8N 67.6W Tuesday evening, and
31.2N 73.6W Wednesday evening. Florence is forecast to strengthen
rapidly into a major hurricane by Monday night, and it is
expected to remain an extremely dangerous major hurricane through
Thursday. Florence will continue to 34.0N 77.5W on Thursday
evening, and weaken to a tropical storm while moving inland near
35.2N 79.0W on Friday evening.

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

$$
MT
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