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Atlantic Tropical Weather Discussion



000
AXNT20 KNHC 300603
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
203 AM EDT FRI SEP 30 2016

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 Matthew at 30/0300 UTC is centered near 14.1N 68.8W or
about 109 NM north of Curacao, moving west at 12 KT. Maximum
sustained winds are 70 KT with gusts to 85 KT. Estimated minimum
central pressure has fallen to 983 mb. Numerous strong convection
is observed from 12.5N to 16.5N between 67W and 71W and from 10N
to 14N between 63W and 67W. Scattered moderate convection is
elsewhere from 10N to 17N between 63W and 71W. Matthew will
continue to strengthen during the new few days as it moves west-
southwest over the central Caribbean. Please refer to the NHC
forecast/advisory under AWIPS/WMO headers WTNT24 KNHC/TCMAT4, or
visit the NHC website at http://hurricanes.gov for additional
details.

...TROPICAL WAVES...

A tropical wave is in the E Atlantic extending from 7.5N to 18.5N
with axis near 27W, moving west at 10 kt over the past 24 hours.
The wave is in a region of favorable deep layer wind shear and in
a region of middle to upper level diffluence. However, both the
TPW imagery and Meteosat enhanced imagery show Saharan dry air W
of the wave axis, which is limiting convection to scattered
showers from 13N to 16N between 23W and 29W.

A tropical wave is in the central Atlantic extending from 6N to
15N with axis near 48W, moving west at 10-15 kt over the past 24
hours. The wave is in a region of unfavorable deep layer wind
shear and Saharan dry air is W of its axis, which is limiting
convection to isolated showers near the vicinity of the wave. 

...ITCZ/MONSOON TROUGH...

The Monsoon Trough extends over Africa reaching the east Atlantic
near 15N17W through 12N24W to 09N34W. The ITCZ begins near 09N35W
to 10N47W. Aside from the convection associated with the tropical
waves, scattered heavy showers are noted off the coast of W Africa
from 07N to 14N E of 19W. This convection may be associated with
the next tropical wave to move off Africa.

...DISCUSSION...

GULF OF MEXICO...

A broad deep layered cyclonic circulation centered over Kentucky 
and associated trough with mean axis along 85W dominates the
eastern half of the Gulf of Mexico and provides support for a
cold front extending from the Big Bend of Florida through 25N88W
to 25N95W. Strong upper level subsidence is occurring in the wake
of the upper trough in the NE basin providing fair weather.
Unfavorable deep layer wind shear support similar weather
conditions in the NW Gulf. A large anticyclone over Mexico
dominates the flow over the western Gulf with moderate to strong
northwesterly flow aloft spreading mid level moisture across the
Bay of Campeche. Diffluent flow aloft between the upper
anticyclone and the trough provide support for scattered showers
and isolated thunderstorms ahead of the cold front in the S-SE
Gulf...and weaker shower activity within 90 NM either side of a
surface trough extending from 24N97W to 19N95W. The cold front
will continue to move south across the eastern Gulf during the
next 24 hours and then will stall Saturday before dissipating
Sunday. Convection will prevail ahead of this boundary affecting
the southern Gulf waters.

CARIBBEAN SEA...

The main feature of concern in the Caribbean is Hurricane 
Matthew located south of Dominican Republic. Matthew remains
embedded within an area of divergent anticyclonic flow aloft as
it tracks westward. Please refer to the special features section
above for details. An upper-level trough extends across the
Florida Peninsula reaching the west Caribbean waters west of 77W.
The upper trough support scattered showers and tstms within 90 nm
off the southern coast of Cuba while diffluent flow aloft support
similar convection within 60 nm off the coast of Honduras. Isolated
showers are observed in the SW basin due to the proximity of the
EPAC Monsoon Trough. Scatterometer data depicts moderate to fresh
northeasterly winds across the basin west of 78W. Expect for
Matthew to intensify as it moves WNW over the central basin
through Saturday.

...HISPANIOLA...

High cloudiness continues to spread across the Dominican Republic
in advance of Hurricane Matthew. The forecast track of the
hurricane should keep the bulk of the heavy precipitation to the
south of Hispaniola. However an increase in the overall moisture
could lead to localized heavy rain in orographically favored
areas. As Matthew turns northward late SUN or MON, the potential
exists for additional heavy rains over Haiti. For additional
information on Matthew, please refer to the special features
section above.

ATLANTIC OCEAN...

Two tropical waves are moving across the basin. Please refer to
the section above for details. A broad mid-level trough extends
across the southeast CONUS and covers the west Atlantic waters W
of 75W, supporting scattered showers and thunderstorms between
70W-79W. The remainder of the basin is dominated by a surface
ridge anchored by a 1034 mb high in the north central Atlantic
near 41N37W.

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

$$
RAMOS