[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 301154 AAA
TWDAT

Tropical Weather Discussion...update to Hurricane Matthew
NWS National Hurricane Center Miami FL
805 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 0600 UTC surface analysis and satellite imagery through
1000 UTC.

...SPECIAL FEATURES...

Hurricane Matthew at 30/1200 UTC is centered near 13.8N 70.3W or
about 113 nm northwest of Punta Gallinas, Colombia and about 450
nm east-southeast of Kingston, Jamaica moving west-southwest at
12 kt. Maximum sustained winds are 90 KT with gusts to 110 KT.
Estimated minimum central pressure is 971 mb. Numerous strong
convection is observed from 12N to 16N between 68W and 72W.
Scattered moderate convection is elsewhere from 11N to 17N
between 64W and 72W. Matthew will continue to strengthen during
the next few days as it moves west-northwest 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 8N to 18N
with axis near 28W, 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
mainly W of the wave axis, which is limiting the convection to
scattered showers from 14N to 16N between 25W and 30W.

A tropical wave is in the central Atlantic extending from 7N to
17N 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 mainly W of its axis, which is
limiting convection to scattered showers from 10N-20N between 39W
and 47W.

...ITCZ/MONSOON TROUGH...

The Monsoon Trough extends over Africa reaching the east Atlantic
near 12N16W through 12N27W to 08N38W. The ITCZ begins near 08N38W
and continues to 08N58W. Aside from the convection associated
with the tropical waves, scattered showers are noted off the
coast of W Africa from 07N to 14N E of 21W. 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 28N82W through 25N90W to 24N96W. Strong
upper level subsidence is occurring in the wake of the upper
trough in the north-central and northeast 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 and weaker
shower activity within 60 NM either side of a surface trough
extending from 24N96W to 20N96W. The cold front will continue to
move south across the eastern Gulf during today 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 120 nm
off the SW 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 Sunday.

...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-80W. The remainder of the basin is dominated by a surface
ridge anchored by a 1031 mb high in the north central Atlantic
near 41N35W.

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

$$
RAMOS/PAW
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