[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 311103
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
703 AM EDT Thu Aug 31 2017

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 0600 UTC surface analysis and satellite imagery through
1100 UTC.

...SPECIAL FEATURES...

T.S. Irma is centered near 16.5N 32.9W at 31/0900 UTC or about
450 nm W of the Cabo Verde Islands, moving W at 10 kt. Estimated
minimum central pressure is 997 mb. Maximum sustained wind speed
is 60 kt with gusts to 75 kt. Numerous moderate and scattered
strong convection is found within 90 nm of the center and within
30 nm of 20N30W. Scattered moderate convection is observed
elsewhere from 11N to 19N between 30W and 37W. See the latest
Intermediate Public Advisory under AWIPS/WMO headers
MIATCPAT1/WTNT31 KNHC and the full Forecast/Advisory under
AWIPS/WMO headers MIATCMAT1/WTNT21 KNHC for more details.

...TROPICAL WAVES...

A tropical wave over the central Atlantic extends from 23N48W to
15N51W to 10N50W, moving west at 10 to 15 kt. The wave coincides
with an amplified 700 mb trough in initial model wind fields. TPW
satellite imagery shows an area of modest deep layer moisture near
the wave axis. Satellite imagery also shows an area of Saharan
dust to the west of the wave to around 58W. Scattered moderate
convection is seen from 09N to 11N between 51W and 55W.

A tropical wave over the central Caribbean extends from 22N76W to
09N78W, moving west at 10 to 15 kt. The wave coincides with
modest 700 mb troughing in initial model wind fields and curvature
of low- level winds in scatterometer data. SSMI TPW imagery shows
this wave is embedded in an area of modest deep layer moisture.
Scattered moderate convection is over E Cuba and Haiti. Isolated
thunderstorms are occurring south of Cuba, west of Jamaica and
over Costa Rica 10N to 21N between 79W to 84W.

A tropical wave over the Bay of Campeche, SE Mexico and Guatemala
extends from 22N91W to 10N91W, moving west around 15 kt. The wave
coincides with subtle 700 mb troughing in initial model wind
fields. TPW satellite imagery shows this wave is embedded in an
area of modest deep layer moisture. Scattered moderate and
isolated strong convection is found over SE Mexico and the Bay of
Campeche from 16N to 21N between 91W and 96W.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from Senegal on the African coast near
16N16W to the Cabo Verde Islands near 16N26W. The monsoon trough
resumes SW of Irma from 14N35W to 12N46W to 10N53W. The ITCZ
continues from 10N53W to 09N60W. Besides the convection
associated with Irma, scattered moderate and isolated strong
convection is present within 120 nm either side of a line from
07N32W to 11N50W.

...DISCUSSION...

GULF OF MEXICO...

Tropical Depression Harvey is centered over Louisiana near
32N92W. Convection associated with Harvey has all but departed the
Gulf as Harvey trudges slowly NE away from the Gulf and continues
to weaken. Only some residual showers and thunderstorms linger
between the western Florida Panhandle and the Yucatan Peninsula in
convergent S to SW flow within 60 nm either side of a line from
31N87W to 22N93W. A stationary front crosses N Florida from 30N81W
to 31N86W. There is no significant convection associated with
this boundary. An area of scattered showers and isolated
thunderstorms has developed over the Bay of Campeche south of 21N
and west of 91W. This area is associated with a tropical wave. See
the tropical waves section for more details.

CARIBBEAN SEA...

A tropical wave is crossing the Caribbean waters. See the
Tropical Waves section above for additional details. The eastern
portion of the E Pacific monsoon trough passes over the southwest
Caribbean near 10N, but convergent upper-level winds in this area
are suppressing convection. An upper-level low is centered over
the Caribbean north of Colombia near 14N75W. Divergent upper-
level winds east of the low are triggering isolated thunderstorms
over the eastern Caribbean from 12N to 15N between 62W and 69W.
Satellite- derived wind data depicts moderate to fresh trades
covering the basin.

...HISPANIOLA...

The showers and thunderstorms that were associated with a
tropical wave have shifted westward to south of Cuba and west of
Jamaica as a tropical wave moves away toward the western
Caribbean. Expect a drier weather pattern during the next couple
of days as the tropical wave moves farther W of the island.

ATLANTIC OCEAN...

T.S. Irma is over the eastern Atlantic, while a tropical wave is
moving over the central Atlantic. Refer to the appropriate
sections above for details about these features. A surface trough
extends from 29N45W to 25N47W. Scattered moderate convection is
present within 60 nm either side of the trough axis. Another
surface trough reaches from 30N52W to 27N54W. There is no
significant convection associated with this feature. The remainder
of the basin is dominated by a 1027 mb high centered over the
Azores near 38N26W that ridges west- southwestward through a 1019
mb high centered SE of Bermuda near 25N57W to the eastern Gulf of
Mexico. The latest satellite-derived wind data indicates moderate
trades prevail south of the ridge axis to the west of 35W.

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

$$
McElroy
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