[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 071800
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
200 PM EDT Fri Sep 7 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 1200 UTC surface analysis and satellite imagery through
1730 UTC.

...SPECIAL FEATURES...

Tropical Storm Florence centered near 25.0N 51.8W at 07/1500 UTC
or 750 nm NE of the Northern Leeward Islands moving W at 7 kt.
Estimated minimum central pressure is 996 mb. Maximum sustained
wind speed is 55 kt with gusts to 65 kt. Scattered moderate
convection is noted from 23N-28N between 47W-53W. The latest NHC
forecast calls for Florence to move northwestward through tonight
before it turns toward to the west on Fri. It is forecast to
weaken slightly today, then re-strengthen beginning this weekend,
reaching minimal hurricane intensity early on Sat and continue to
gradually intensify through Sunday. See the latest NHC
forecast/advisory under AWIPS/WMO headers MIATCPAT1/WTNT31 KNHC
for more details.

Potential Tropical Cyclone Eight is centered near 13.1N 17.8W at
07/1500 UTC or 400 nm ESE of the Southernmost Cabo Verde Islands
moving W at 9 kt. Estimated minimum central pressure is 1004 mb.
Maximum sustained wind speed is 30 kt with gusts to 40 kt.
Scattered moderate convection is noted from 09N-16N and east of
27W. See latest NHC forecast/advisory under AWIPS/WMO headers
MIATCPAT3/WTNT33 KNHC for more details.

Satellite data indicate that the circulation of a low pressure
system located about 700 miles west of the Cabo Verde Islands
is well defined.  However, the associated shower and thunderstorm
activity has not been sufficiently organized to designate the
system as a tropical depression.  Only a slight increase in
organization would lead to the initiation of advisories on this
system, possibly as early as later today or tonight.  This low is
expected to move slowly westward across the tropical Atlantic Ocean
during the next several days.The chance of this system becoming a
tropical cyclone during the next 48 hours is now in the high
range. Please read the latest NHC Tropical Weather Outlook under
AWIPS/WMO headers MIATWOAT/ABNT20 KNHC for more information.

...TROPICAL WAVES...

A tropical wave has its axis along 88W south of 20N, moving
westward at 10 to 15 kt. Scattered showers are noted within 90 nm
on either side of the wave's axis.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from the Special Features low and wave
along 17N to the next 1007 mb low to 09N47W. The ITCZ begins from
this point to 09N61W. Aside from the convection related to the
Special Features' lows, scattered moderate convection prevails
along the ITCZ.

...DISCUSSION...

GULF OF MEXICO...

Upper-level cyclonic flow is located over eastern Louisiana and
southern Texas and strong northeast upper-level winds are over
eastern Gulf of Mexico along the western periphery of the large
upper low that is over the northwestern Bahamas. A moist and
unstable atmosphere along with plenty available instability is
allowing for scattered showers to be over much of the eastern
Gulf waters mainly east of 87W. Expect for this activity to
remain through at least tonight.

Weak ridging from the Carolinas to the Texas coast will shift
northward through Sat, supporting gentle to moderate easterly
winds and modest seas into early next week. The exception will be
fresh winds pulsing off west of the Yucatan peninsula, mainly
during the late evenings through the next few days due to the
thermal trough that will develop over the Yucatan Peninsula and
move west over the Bay of Campeche.

CARIBBEAN SEA...

Please refer to the Tropical Waves section above for details
regarding a tropical wave along 88W.

An upper-level trough axis stretches from western Cuba to northeastern
Honduras. Associated cyclonic flow covers the western Caribbean
west of a line from Hispaniola to Panama. Upper-level
anticyclonic flow covers the eastern Caribbean as the culprit
anticyclone remains anchored near 15N68W. At this time, scattered
moderate convection is noted south of 16N between 75W-81W.

A relatively weak surface ridge in the western Atlantic Ocean
will maintain moderate to fresh trade winds in most of the region
into Sun. Building high pressure over the eastern Gulf of
Mexico will allow fresh to strong E to SE winds and building
seas over portions of the NW Caribbean late Sun and Mon.

ATLANTIC OCEAN...

Please read the Special Features section above for details about
Florence, Potential T.C. Eight, and the tropical wave/low in the
east Atlantic with a chance of tropical development.

A large upper-level low centered over South Florida and the
northwestern Bahamas extends a trough southwestward across west
Cuba. The low continues progressing in a westward motion. Its
associated upper-level cyclonic flow covers the Atlantic west of
66W, and northward to about 35N. A surface trough is analyzed
from 31N79W to 24N80W. Another surface trough is analyzed from
near 31N71W to 27N73W. Scattered showers prevail west of 74W while
scattered to numerous moderate convection is noted north of 30N
between 62W-75W.

A weak pressure pattern will maintain gentle to moderate easterly
winds across the western Atlantic area into early next week.
Tropical Storm Florence is forecast by the latest NHC advisory to
move across the northeastern NHC/TAFB offshore waters zones Mon
through Tue of next week. Easterly swell, in advance of Florence,
are forecast to propagate through the open waters east of the
Bahamas beginning this upcoming weekend.

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

$$

ERA
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