[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 021042
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
642 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 0600 UTC surface analysis and satellite imagery through
1030 UTC.

...SPECIAL FEATURES...

Hurricane Irma is centered near 19.0N 41.8W at 02/0900 UTC or
about 1145 nm E of the Leeward Islands moving W at 12 kt.
Estimated minimum central pressure is 970 mb. Maximum sustained
wind speed is 95 kt with gusts to 115 kt. Numerous moderate
convection is within from 17N to 20N between 40W and 43W.
Scattered moderate convection is elsewhere from 16N to 21N
between 36W and 46W. Irma is expected to remain a powerful
hurricane into early next week. 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 associated with a 1012 mb low
located near 08N24W. Its axis extends from 15N23W to the low to
04N24W, moving W at 10 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 in the
northern wave environment. Scattered moderate convection is W of
the low center from 04N to 13N between 25W and 33W. Isolated
showers are elsewhere from 03N to 08N E of 23W.

A tropical wave is moving across the Lesser Antilles. The wave
axis extends from 21N60W to 10N61W, moving W at 5-10 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.
Isolated showers are occurring in the Leeward Islands.

A tropical wave is moving across the Yucatan Peninsula, Guatemala,
San Salvador into EPAC waters. Its axis extends from 20N88W to
10N89W, moving W at 15 kt. The wave is in a region of moderate
vertical wind shear, however is underneath upper level diffluent
flow, which supports isolated showers inland.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from the African coast near 12N16W to
08N24W to 08N32W. For convection information, 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 E Bay of Campeche. The troughing
supports a stationary front extending across SW Georgia, SE
Alabama to 30N89W. Southeast of the upper trough base, a ridge
over the Yucatan Peninsula extending over the far NW Caribbean
generates diffluence aloft, which is supporting scattered heavy
showers and tstms in the SE Gulf S of 27N E of 89W. Diffluence
aloft also support scattered showers in the W Bay of Campeche
where a surface trough extends from 23N92W to 18N95W. Isolated
showers are elsewhere in the SW Gulf. Otherwise, mostly light
variable flow is across the northern half of the Gulf. Moderate
E flow is in the Bay of Campeche associated with the surface
trough. The upper trough will prevail over the basin through
early next week, thus supporting the continuation of showers in
the E and SW basin.

CARIBBEAN SEA...

A tropical wave is moving across northern Central America, and the
Yucatan Peninsula 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 82W. Most of this activity is expected to move west of the
area by tonight. A second tropical wave entered the far E
Caribbean waters early this morning and is supporting isolated
showers in the Leeward Islands. See tropical waves section for
further details. 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. 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 today.
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
divergence aloft across the far western SW North Atlc waters.
This environment aloft supports scattered heavy showers and tstms
generally N of 23N W of 76W. Farther east, a stationary front
extends from 30N55W SW to 25N62W. Otherwise, surface ridging
prevails elsewhere N of 22N.

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

$$
Ramos
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