[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 020605
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
205 AM EDT Sat Sep 2 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 19.1N 40.5W at 02/0300 UTC or
about 1220 nm E of the Leeward Islands moving W at 12 kt.
Estimated minimum central pressure is 967 mb. Maximum sustained
wind speed is 100 kt with gusts to 130 kt. Numerous moderate
convection is within from 17N to 20N between 39W and 42W. Scattered
moderate is elsewhere from 17N to 21N between 37W and 45W. Irma
is expected to remain a powerful hurricane through the weekend. Interests
in the northern Leeward Islands should monitor the progress of
this system. See the latest NHC Forecast/Advisory under AWIPS/WMO
headers MIATCMAT1/WTNT21 KNHC for more details.

...TROPICAL WAVES...

A tropical wave is in the E Atlc just W of the Cape Verde Islands.
Its axis extends from 15N28W to 07N26W, moving W at 15 kt. The
wave is in a region of low vertical wind shear and is underneath
middle level diffluent flow. Enhanced IR imagery show some
Saharan dry air and dust NE of the wave axis, however the CIRA LPW
show abundant low level moisture in the wave environment, which is
supporting scattered moderate convection and tstms from 05N to 14N
between 26W and 32W.

A tropical wave is in the central Atlc, just E of the Lesser
Antilles. The wave axis extends from 21N56W to 10N56W, moving W at
5 kt. Even though the wave is in a region of low vertical wind
shear, water vapor imagery show dry air subsidence at the middle
to upper levels while the CIRA LPW imagery show patches of dry air
in the wave environment. No deep convection is observed at this
time.

A tropical wave is moving across Belize, Honduras, San Salvador
into EPAC waters. Its axis extends from 19N87W to 10N88W, moving W
at 15 kt. The wave is in a region of moderate vertical wind shear,
however abundant moisture in its environment along with upper
level diffluence support scattered heavy shower and tstms W of
81W, including the Yucatan Channel.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from the African coast near 13N16W to
12N20W to 06N28W. Scattered to isolated showers are from 05N to 11N
between 14W and 20W. Otherwise, see tropical waves section.

...DISCUSSION...

GULF OF MEXICO...

Water vapor imagery indicates a middle to upper level trough
extending from over the Ohio River valley and southern Mississippi
River valley to a base over the Bay of Campeche. The troughing
supports a stationary front extending across SW Georgia, SE
Alabama to 28N88W. South of the upper trough base, a ridge over
the Yucatan Peninsula extending over the far NW Caribbean generate
diffluence aloft, which is supporting scattered heavy showers and
tstms in the SE Gulf S of 28N E of 88W. Diffluence aloft also
support scattered showers in the E Bay of Campeche where a surface
trough extends from 22N88W to 16N91W. Isolated showers are
elsewhere in the SW Gulf. Otherwise, a surface ridge extends
across the Florida Peninsula into the central basin, being
anchored by a 1017 mb high near 27N87W. This is providing with mostly
light anticyclonic flow to the northern half of the Gulf. Moderate
NE flow is off the Yucatan Peninsula associated with the surface
trough.

CARIBBEAN SEA...

A tropical wave is moving across northern Central America into the
EPAC waters. This wave is underneath upper level diffluent flow
that along with abundant moisture in the NW Caribbean waters
support scattered heavy showers and tstms W of 81W. Most of this
activity is expected to move west of the area by Saturday night.
Water vapor imagery show dry air aloft in the remainder basin,
which is supporting fair weather conditions. Otherwise, moderate
to fresh trades are basin-wide, except for strong winds in the
south-central basin along the coast of Colombia. An approaching
tropical wave currently with axis along 57W will impact the
Lesser Antilles on Saturday with increase cloudiness and a greater
chance for isolated showers and tstms. Looking beyond this
weekend, Hurricane Irma looms across the central tropical Atlc
and is forecast to approach 60W Tuesday night into Wednesday.

...HISPANIOLA...

Water vapor imagery show dry air aloft, which continue to support fair
weather and clear skies across the island. The overall dry
weather pattern is expected to persist through late Saturday.
However, a tropical wave will approach the Island early Sunday
morning and is forecast to bring scattered to isolated showers to
the Island.

ATLANTIC OCEAN...

Hurricane Irma remains the main concern in the basin. See special
features for further details. A middle to upper level trough is
progressing over the mid-Atlc and SE CONUS regions and generates
divergece aloft across the far western SW North Atlc waters. This
environment aloft supports scattered heavy showers and tstms
generally N of 25N W of 77W, including interior portions of
Florida. Farther east, an upper level low supports a stationary
front extending from 30N55W SW to 24N65W. Otherwise, surface
ridging prevails elsewhere N of 22N.

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

$$
Ramos
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