[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 010518
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
118 AM EDT Fri Sep 1 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 0000 UTC surface analysis and satellite imagery through
0500 UTC.

...SPECIAL FEATURES...

Hurricane Irma is centered near 17.8N 35.6W at 01/0300 UTC or
about 675 nm west of the Cabo Verde Islands, moving west-
northwest at 10 kt. Estimated minimum central pressure is 967 mb.
Maximum sustained wind speed is 100 kt with gusts to 120 kt.
Numerous moderate and scattered strong convection is seen within
60 nm of the center and within 60 nm of 12.5N41.5W. Scattered
moderate and isolated strong convection is found elsewhere from
14N to 21N between 32W and 38W. Irma is a category 3 hurricane on
the Saffir- Simpson Hurricane Wind Scale. 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 21N53W to
09N55W, moving west around 15 kt. The wave coincides with an
amplified 700 mb trough in initial model wind fields. The SSMI TPW
satellite imagery shows the wave is embedded in an area of modest
deep layer moisture. Satellite imagery also shows an area of
Saharan dust to the west of the wave. No significant convection is
currently associated this wave.

A tropical wave over the western Caribbean extends from 21N82W to
09N82W, moving west around 15 kt. The wave coincides with modest
700 mb troughing in initial model wind fields. SSMI TPW imagery
shows this wave is embedded in an area of modest deep layer
moisture. Scattered moderate to isolated strong convection is
present over western Cuba from 21N to 24N between 79W and 85W.

A tropical wave over the Bay of Campeche extends from 22N95W to
11N96W, moving west at 15 to 20 kt. The wave coincides with subtle
700 mb troughing in initial model wind fields. SSMI TPW satellite
imagery shows this wave is embedded in an area of modest deep
layer moisture. Scattered moderate to isolated strong convection
is occurring over SE Mexico and the adjacent waters of the Bay of
Campeche and Gulf of Tehuantepec from 14N to 21N between 92W and
97W.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from 12N16W to 12N19W to 14N26W then
resumes from 13N37W to 10N53W. The ITCZ reaches from 10N56W to
09N61W. Numerous moderate and isolated strong convection is
observed off the coast of W Africa within 60 nm either side of a
line from 07N23W to 13N27W. Scattered moderate and isolated strong
convection is observed elsewhere from 05N to 08N between 26W and
40W. Numerous moderate and scattered strong convection is taking
place within 60 nm of 12.5N41.5W. Scattered moderate and isolated
strong convection is observed elsewhere from 11N to 14N between
39W and 44W.

...DISCUSSION...

GULF OF MEXICO...

Tropical Depression Harvey is centered over N Mississippi, moving
NE and weakening. In the upper levels, an upper level trough
extending SW over the NW Gulf from Louisiana is producing strong
subsidence. Convergent upper-level winds are generally inhibiting
convection over the Gulf except near western Cuba and over the Bay
of Campeche. See the tropical waves section for more details. The
remainder of the Gulf has a large amount of upper level moisture.
Expect the upper level trough to move E and maintain generally
dry conditions over the northern Gulf over the next 24 hours.

CARIBBEAN SEA...

A tropical wave is over the central Caribbean. See above. Farther
S, the eastern portion of the E Pacific monsoon trough passes
over Costa Rica and Panama into norther Colombia. Convection
associated with the trough is limited to a small area of NW
Colombia. A weak upper-level trough heading SW into the NE
Caribbean is producing upper-level convergence and inhibiting
convection over the NE Caribbean while another upper-level trough
from western Cuba to Panama is producing weak upper-level
convergence over the western Caribbean. A tropical wave over the
western Caribbean is generating convection over western Cuba. See
the tropical waves section for more details. Satellite derived
wind data depicts moderate to fresh trades covering the basin.

...HISPANIOLA...

Presently there is no significant convection over the island.
Expect a dry weather pattern to prevail across the island during
the next couple of days as a weak upper-level trough passes
overhead and inhibits convection.

ATLANTIC OCEAN...

Hurricane Irma is over the eastern Atlantic, and a tropical wave
is over the central Atlantic. Please see above. A frontal
boundary extends across the W Atlantic, analyzed as a cold front
from 32N54W to 26N68W, then continues as a stationary front to
31N81W. Scattered showers and isolated thunderstorms are observed
along and up to 60 nm ahead of the cold front to the east of 60W.
A 1019 mb surface high is centered N of the front near 32N70W. A
surface trough extends from 27N48W to 24N50W. Scattered moderate
and isolated strong convection is taking place within 60 nm of
23N49W. The remainder of the basin is dominated by a 1030 mb high
centered over the Azores near 38N26W that ridges SW to near
26N53W.

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

$$
McElroy
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