[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 090529
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
129 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 0000 UTC surface analysis and satellite imagery through
0500 UTC.

...SPECIAL FEATURES...

The center of Tropical Storm Florence at 09/0300 UTC is near
24.6N 55.2W. Florence is moving W, or 270 degrees, 05 knots. The
estimated minimum central pressure is 989 mb. The maximum
sustained wind speeds are 60 knots with gusts to 75 knots.
24-hour rainfall totals that are listed for the period that
ended at 09/0000 UTC...according to the PAN AMERICAN TEMPERATURE
AND PRECIPITATION TABLES...MIATPTPAN/SXCA01 KNHC...are 1.25 in
Bermuda. Scattered moderate to strong rainshowers are within 30 nm
of the center everywhere. Scattered moderate to isolated strong
rainshowers are within 120 nm of the center in the NE quadrant,
and within 150 nm of the center in the SW quadrant. The official
forecast continues to call for a period of rapid intensification
in about 12 to 24 hours. Florence is expected to reach major
hurricane intensity between 36 and 48 hours, with additional
strengthening after that. Florence is forecast to be an intense
hurricane on days 3 through 5 as it moves across the warm waters
of the southwestern Atlantic Ocean, between the Bahamas and
Bermuda, and then as it heads toward the southeast U.S.A. coast.
Public Advisories for Tropical Storm Isaac are issued under WMO
header WTNT31 KNHC and under AWIPS header MIATCPAT1.
Forecast/Advisories for Tropical Storm Isaac are issued under WMO
header WTNT21 KNHC and under AWIPS header MIATCMAT1.

The center of Tropical Storm Isaac at 09/0300 UTC is near 14.4N
37.5W. Isaac is moving W, or 270 degrees, 07 knots. The estimated
minimum central pressure is 1002 mb. The maximum sustained wind
speeds are 45 knots with gusts to 55 knots. Numerous strong
rainshowers are within 150 nm of the center in the S semicircle,
and within 60 nm of the center in the NE quadrant. 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.

The center of Tropical Storm Helene at 09/0300 UTC is near 13.2N
22.8W. HELENE is about 250 km to the SE of the southernmost Cabo
Verde Islands. HELENE is moving W, or 260 degrees, 11 knots. The
estimated minimum central pressure is 999 mb. The maximum
sustained wind speeds are 50 knots with gusts to 60 kt. Scattered
to numerous strong rainshowers are within 240 nm of the center in
the SE quadrant, and within 150 nm of the center in the SW
quadrant. Public Advisories for Tropical Storm Isaac are issued
under WMO header WTNT33 KNHC and under AWIPS header MIATCPAT3.
Forecast/Advisories for Tropical Storm Isaac are issued under WMO
header WTNT23 KNHC and under AWIPS header MIATCMAT3.

...TROPICAL WAVES...

A tropical wave is along 81W/82W from Cuba and 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. It also
has been interacting with an upper level cyclonic circulation
center that is in the eastern Gulf of Mexico. Isolated moderate to
locally strong rainshowers are from 13N northward from 76W
westward.

...MONSOON TROUGH/ITCZ...

The ITCZ is along 09N43W 09N50W 08N57W. Isolated moderate to
locally strong rainshowers are elsewhere from 08N to 12N from 36W
eastward. Rainshowers are possible elsewhere from 10N southward
between 36W and 60W.

...DISCUSSION...

GULF OF MEXICO...

An upper level trough extends from a 24N87W cyclonic circulation
center, to 20N99W, inland in Mexico. Upper level cyclonic wind
flow covers the Gulf of Mexico and surrounding coastal plains.
Isolated moderate rainshowers are from 90W eastward. Earlier
scattered moderate to isolated strong rainshowers that were in the
Yucatan Peninsula have dissipated/have been dissipating.

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...

Upper level cyclonic wind flow covers the Caribbean Sea to the NW
of the line that runs from SE Cuba to NE Nicaragua. Isolated
moderate to locally strong rainshowers are from 13N northward from
76W westward.

Tropical Storm Isaac near 14.4N 37.5W 1002 mb at 11 PM EDT moving
W at 7 kt. Maximum sustained winds 45 kt gusts 55 kt. Isaac will
move to 14.5N 40.9W Sun evening and strengthen to a hurricane near
14.5N 43.5W Mon morning. Isaac will continue W to 14.5N 46.1W Mon
evening, and 14.5N 51.5W Tue evening. Isaac will change little in
intensity as it approaches the Lesser Antilles near 14.6N 57.0W
Wed evening, and continue into the eastern Caribbean near 15.0N
62.9W 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.

An upper level cyclonic circulation center is near 30N70W. A 1014
mb low pressure center is near 31N68W.Upper level cyclonic wind
flow also is from 27N northward from 75W westward. Isolated
moderate rainshowers cover the Atlantic Ocean to the NW of the
line that passes through 32N59W to 20N70W.

Tropical Storm Florence near 24.6N 55.2W 989 mb at 11 PM EDT
moving W at 5 kt. Maximum sustained winds 60 kt gusts 75 kt.
Florence will strengthen to a hurricane near 24.5N 55.9W Sun
morning, move to 24.8N 57.4W Sun afternoon, 25.2N 59.3W Mon
morning, 25.8N 61.8W Mon afternoon, and 27.5N 67.5W Tue afternoon.
Florence will change little in intensity as it moves across the
north-central offshores near 30.0N 73.5W Wed afternoon, then
continue to 33.8N 77.8W Thu afternoon. A weak pressure pattern
across the SW N Atlc will maintain gentle to moderate mainly
easterly winds elsewhere across the area through Monday.

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

$$
MT
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