[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 151724
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
124 PM EDT Sat Sep 15 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
1715 UTC.

...SPECIAL FEATURES...

Tropical Storm Florence is centered near 33.6N 79.6W at 15/1500
UTC, or 30 nm W of Myrtle Beach South Carolina, moving W at 2 kt.
Estimated minimum central pressure is 995 mb. Maximum sustained
wind speed is 40 kt with gusts to 50 kt. Scattered moderate
convection prevails north of 31N between 74W-82W. Latest NHC
advisory has Florence turning north- westward through the
Carolinas and to the Ohio Valley this weekend. Gradual weakening
is forecast while Florence moves farther inland during the next
couple of days, and it is likely to weaken to a tropical
depression in 24 hours. See the latest NHC forecast/advisory under
AWIPS/WMO headers MIATCPAT1/WTNT31 KNHC for more details.

Tropical Storm Helene is centered near 38.8N 34.0W at 15/1500 UTC,
or 130 nm WSW of Flores Island in the western Azores, moving NE
at 18 kt. Estimated minimum central pressure is 988 mb. Maximum
sustained wind speed is 60 kt with gusts to 75 kt. Scattered
moderate convection prevails north of 37N between 30W-37W. Helene
is forecast to turn northeast by tonight/early Sun, passing near
or over the Azores. See the latest NHC forecast/advisory under
AWIPS/WMO headers MIATCPAT3/WTNT33 KNHC for more details.

Tropical Storm Joyce is centered near 32.0N 41.0W at 15/1500 UTC or
770 nm WSW of the Azores moving ENE at 12 kt. Estimated minimum
central pressure is 1001 mb. Maximum sustained wind speed is 40
kt with gusts to 50 kt. Latest satellite imagery shows scattered
moderate convection north of 33N between 38W-42W. Joyce is
forecast by the latest NHC advisory to turn northeastward with an
increase in forward speed today, with some slight strengthening
possible. Gradual weakening is forecast to begin by Sun.See the
latest NHC forecast/advisory under AWIPS/WMO headers MIATCPAT5/WTNT35
KNHC for more details.

...TROPICAL WAVES...

A far eastern Atlantic tropical wave has its axis along 33W from
08N to 19N, moving westward at 10-15 kt. The wave is surrounded
by a rather dry environment, which is inhibiting deep convection
from forming along or near it. Only isolated showers are within
75 nm either side of the wave axis, mainly where it crosses the
monsoon trough.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from 12N17W to 09N26W. The ITCZ
is from 08N38W to 08N59W. Aside from the shower activity
associated with the tropical wave along 33W, scattered moderate
convection is within 120 nm on either side of the ITCZ.

...DISCUSSION...

GULF OF MEXICO...

A 1014 mb surface high is centered near 28N87W. T.S. Florence is
centered to the northeast of the basin enhancing the pressure
gradient across the east Gulf waters. With this, moderate westerly
flow prevails north of 28N and east of 86W. To the west, a
surface low centered over southern Texas is enhancing scattered to
numerous moderate convection north of 21N and west of 96W. An
upper-level low is centered over the Yucatan Channel enhancing
shower activity south of 25N between 86W-91W.

CARIBBEAN SEA...

An upper level cyclonic circulation center is located near the
Yucatan Channel enhancing scattered showers west of 83W. To the
south, the monsoon trough extends along Panama with scattered
moderate convection south of 11N between 76W-82W. To the east, the
remnants of Isaac are centered near 15N71W. Its pressure is 1006
mb. Scattered moderate convection is observed between 66W-74W
affecting the adjacent waters south of Puerto Rico and
Hispaniola. Moderate to fresh winds prevail with this low over the
central Caribbean. Elsewhere, gentle to moderate trades prevail
east and west of the low. Strong nocturnal trades are forecast
off the northwest coast of Colombia on Mon and Tue nights.

ATLANTIC OCEAN...

Please refer to the Special Features section above, for details
on Florence, Helene, and Joyce, and the Tropical Waves section for
details about the wave along 33W.

An upper-level trough extends across the central Atlantic . A 1012
mb surface low has developed near 31N61W. A trough extends from
he low to the east along 32N. Scattered moderate convection is
developing in the vicinity of these features mainly north of 27N
between 57W.64W.

A surface ridge will remain about stationary from near 32N68W to
southeastern Florida through the weekend. The ridge will shift
northward by the middle of the next week.

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

$$

ERA
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