[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 040605
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
205 AM EDT Mon Sep 4 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
0545 UTC.

...SPECIAL FEATURES...

Hurricane Irma is centered near 17.2N 51.0W at 04/0300 UTC or
about 615 nm E of the Leeward Islands moving W at 12 kt.
Estimated minimum central pressure is 961 mb. Maximum sustained
wind speed is 100 kt with gusts to 120 kt. Numerous strong
convection is from 16N to 19N between 50W and 52W. Scattered
moderate convection is elsewhere from 13N to 20N between 48W and
56W. See the latest NHC 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 is in the E Atlc associated with a 1013 mb low
located near 10N33W. The wave axis extends from 17N33W to the low
and it has been moving W at 10 kt. The wave is in a region of low
to moderate vertical wind shear, however enhanced IR imagery
continue to show some Saharan dry air and dust in the wave
environment. CIRA LPW imagery at the lower levels confirm the
presence of dry air in the vicinity of the wave. Shallow moisture
and divergence aloft support scattered moderate convection from
06N to 14N between 32W and 40W.

A tropical wave is in the central Caribbean with axis extending
from 20N74W to 09N76W, moving W at 20-25 kt. The wave is in a
region of low vertical wind shear, however it continues being
affected by dry air subsidence from aloft, except N of 18N where
upper level diffluence support scattered showers and tstms across
Western Haiti and the Windward Passage.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from the African coast near 12N16W to
11N30W to 09N37W. Aside from the convection associated with the
tropical wave in the E Atlc, scattered moderate convection is from
04N to 11N E of 30W.

...DISCUSSION...

GULF OF MEXICO...

Water vapor imagery indicates a middle to upper level trough
extending over the far NW Atlc to a broad base over S Florida.
Middle to upper level diffluent flow prevails in the SE basin,
thus supporting the continuation of scattered to isolated showers
S of 26N. A surface trough continues in the SW Gulf, extending
from 24N92W to 18N93W, which is generating scattered heavy showers
and tstms. Fresh to strong winds are observed in the area of
strongest convection or the E Bay of Campeche E of the trough
axis. This feature is expected to dampen out by late Monday night
into early Tuesday. Elsewhere, gentle to moderate easterly winds
prevail with isolated showers occurring across the NW waters W of
93W. A surface ridge axis is expected to anchor along 30N Tuesday,
gradually slide southward, and weaken by Wednesday as a weak
frontal boundary moves off the Texas and Louisiana coasts.

CARIBBEAN SEA...

Middle level diffluent flow supports isolated showers and tstms
in the Gulf of Honduras. In the SW basin, the E extension of the
EPAC monsoon trough support scattered showers and tstms S of 12N.
Otherwise, upper diffluence underneath a tropical wave that moves
across central Caribbean waters supports scattered heavy showers N
of 18N between 67W and 79W, including the Windward Passage. For
further details on the wave, see section above. Water vapor
imagery show dry air aloft across the remainder basin, which
subsidence is supporting fair weather conditions. Otherwise,
moderate to fresh trades are basin-wide. Looking beyond today,
major Hurricane Irma looms across the central tropical Atlc and
is forecast to approach 60W Tuesday evening into the overnight
hours.

...HISPANIOLA...

Scattered showers and tstms are expected to continue through
Monday as a tropical wave continues to move westward away from the
Island. Conditions will gradually improve on Tuesday. Looking
ahead, Hurricane Irma is forecast to approach from the east and
likely be centered N-NE of the island Thursday afternoon.

ATLANTIC OCEAN...

Major Hurricane Irma continue to represent a threat for the NE
Caribbean Tue through late Wednesday. See special features for
further details. A middle to upper level trough is progressing
over far NW Atlc waters supporting isolated showers over the SW
North Atlc. Farther east, an upper level low supports a dissipating
stationary front extending from 30N62W SW to 27N67W. Scattered showers
and tstms are from 24N to 29N between 60W and 64W. Surface ridging
prevails elsewhere N of 24N.

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

$$
Ramos
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