[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 021747
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
147 PM 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 1200 UTC surface analysis and satellite imagery through
1715 UTC.

...SPECIAL FEATURES...

Hurricane Irma is centered near 18.8N 43.3W at 02/1500 UTC or
about 1060 nm E of the Leeward Islands moving W at 13 kt.
Estimated minimum central pressure is 973 mb. Maximum sustained
wind speed is 95 kt with gusts to 115 kt. Numerous strong
convection is from 18N-20N between 43W-45W. Scattered moderate
convection is elsewhere from 17N-21N between 41W-45W. 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 Atlantic associated with a 1012 mb
low located near 09N25W. Its axis extends from 14N24W to the low
to 03N25W, moving W at 10 kt. The wave is a low amplitude wave.
SSMI TPW imagery shows the wave is in a very moist area. The wave
is also within a distinct 700 mb trough. Isolated moderate
convection is over a large area from 04N-13N between 20W-33W.

A tropical wave is moving across the Lesser Antilles. The wave
axis extends from 22N62W to 10N64W, moving W at 5-10 kt. SSMI
TPW imagery shows the wave is in a moist area N of 15N, and less
so S of 15N. The wave is also within a distinct surface and 700
mb trough. Isolated moderate convection is over the Leeward
Islands from 16N-20N between 60W-63W.

A tropical wave is moving across the Yucatan Peninsula, Guatemala,
San Salvador into EPAC waters. Its axis extends from 21N89W to
07N90W, moving W at 15 kt. Scattered moderate to strong convection
is E of the wave axis over the W Caribbean from 17N-24N between 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. 82W- 87W.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from the African coast near 12N16W to
09N25W to 12N38W to 10N48W. The ITCZ continues from 10N48W to
12N61W. Besides the convection mentioned with the tropical waves,
isolated moderate convection is S of the monsoon trough from
04N-12N between 07W-20W.

...DISCUSSION...

GULF OF MEXICO...

The tail end of a cold front is over the Florida Panhandle and NE
Gulf of Mexico from 31N84W to 28N90W. Scattered moderate
convection is SE of the front from 26N-29N between 82W-88W.
Scattered showers and isolated thunderstorms are also over the
Florida Peninsula. A surface trough is over the Bay of Campeche
from 22N96W to 18N94W. Scattered moderate convection is from
18N-22N between 92W-97W. In the upper levels, an upper level
trough is over the Gulf with axis along 90W. Strong subsidence is
over the NW Gulf, while the remainder of the Gulf has upper level
moisture. Expect the cold front to slowly move E over the next 24
hours with continued convection. Also expect the convection over
the Bay of Campeche to persist.

CARIBBEAN SEA...

A tropical wave is over the Yucatan Peninsula producing convection
over the NW Caribbean. Another tropical wave is over the E
Caribbean producing scattered showers over the Leeward Islands.
Elsewhere, the eastern extent of the E Pacific monsoon trough
traverses Costa Rica and Panama with scattered moderate
convection S of 11N. In the upper levels, a large upper level
ridge is over the central and E Caribbean with strong subsidence.

...HISPANIOLA...

Water vapor imagery shows dry air aloft, that supports fair
weather and clear skies across the island. These conditions are
expected to persist until this evening. A tropical wave is
approaching the Island, and is forecast to bring scattered
showers to the island Sunday.

ATLANTIC OCEAN...

Hurricane Irma remains the main concern in the basin. See special
features for further details. Scattered showers are over the W
Atlantic W of 78W to include the N Bahamas. The tail end of a
stationary front is over the central Atlantic from 31N56W to
24N65W. Scattered showers are within 90 nm of the front. A 1029 mb
high is centered S of the Azores near 36N29W with a ridge axis
extending SW to 30N47W. Of note in the upper levels, an upper
level low is centered over the W Atlantic near 27N57W.

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

$$
Formosa
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