[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 120605
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
105 AM EST SAT NOV 12 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
0515 UTC.

...SPECIAL FEATURE...

...A GALE WARNING IN THE GULF OF MEXICO...

A reinforcing cold front is forecast to move southward across the
Gulf of Mexico Saturday night and Sunday. A surface ridge will
surge southward across eastern Mexico. Northerly winds will
increase in speed to minimal gale force starting on Saturday
evening, and then they will diminish to less than gale force
shortly after sunrise on Sunday. The sea heights will build
locally to 12 feet during the times of the fastest wind speeds.
Please read the HIGH SEAS FORECAST...MIAHSFAT2/FZNT02 KNHC...
and the OFFSHORE FORECAST...MIAOFFNT4/FZNT24 KNHC...for more
details.

...THE ITCZ/THE MONSOON TROUGH...

The Monsoon Trough reaches the coastal areas of Guinea-Bissau
near 12N16W, to 06N22W. The ITCZ continues from 06N22W to 04N25W
and 07N43W. Convective precipitation: isolated moderate from 10N
southward from 40W eastward.

...DISCUSSION...

...THE GULF OF MEXICO...

Upper level anticyclonic wind flow is moving from Mexico near
20N100W, across the Gulf of Mexico, and beyond Florida.
A SE-to-NW oriented surface trough extends from the coastal
waters of NW Cuba into the central Gulf of Mexico. A stationary
front continues from the central Gulf of Mexico, and it curves
westward and southward, into the SW corner of the Gulf of Mexico.
A north-to-south oriented surface trough is between 90W and the
stationary front. Convective precipitation: rainshowers are
possible in much of the area, except for parts of the area that
are from 26N southward from 89W eastward.

A surface ridge passes through the deep south of Texas, through
the coastal plains of Mexico, into the Isthmus of Tehuantepec of
southern Mexico. Gale-force winds are blowing in the Gulf of
Tehuantepec on the eastern Pacific Ocean side of southern Mexico.
Please read the Eastern Pacific Ocean HIGH SEAS
FORECAST...MIAHSFEP2/FZPN03 KNHC...and the Eastern Pacific Ocean
TROPICAL WEATHER DISCUSSION...MIATWDEP/AXPZ20 KNHC...for more
details.

...LOW LEVEL CLOUD CEILINGS AND WEATHER FOR THE OFFSHORE OIL
PLATFORM SITES THAT ARE IN THE AREA WHOSE BOUNDARIES ARE FROM 27N
NORTHWARD AND FROM 88W WESTWARD...

LIFR: none.

IFR: none.

MVFR: none.

LOW LEVEL CLOUD CEILINGS AND WEATHER...FOR THE COASTAL PLAINS OF
THE U.S.A. FROM THE DEEP SOUTH OF TEXAS TO FLORIDA...

TEXAS: VFR/no ceilings. LOUISIANA: LIFR in Patterson. MISSISSIPPI:
LIFR in Pascagoula. ALABAMA: VFR/no ceilings. FLORIDA: MVFR in
Brooksville and Sarasota.

...THE CARIBBEAN SEA...

Upper level anticyclonic wind flow is moving across the area,
from Central America and South America, toward the NE, and across
the open waters of the Caribbean Sea.

A surface trough is along 71W/72W from the Dominican Republic to
La Peninsula de la Guajira of NE Colombia. Convective
precipitation: isolated moderate between 66W and 74W.

A NW-to-SE oriented surface trough extends from parts of the NW
Caribbean Sea into the SW corner of the area. The monsoon trough
is along 10N between Colombia and Costa Rica. Convective
precipitation: scattered to numerous strong from 14N southward
from 73W westward.

The 24-HOUR rainfall total in inches for the period ending at
12/0000 UTC...according to the PAN AMERICAN TEMPERATURE AND
PRECIPITATION TABLES...MIATPTPAN/SXCA01 KNHC...is 0.01 in
Guadeloupe.

...HISPANIOLA...

Upper level NW wind flow is moving across the area. Convective
precipitation: isolated moderate to locally strong in the coastal
waters of eastern Hispaniola. some precipitation is inland also.

SURFACE OBSERVATIONS...for Port-au-Prince in Haiti, at 12/0100
UTC: VFR...a ceiling at 5000 feet. for the DOMINICAN REPUBLIC:
Barahona at 12/0000 UTC: rain and thunder. Santo Domingo: VFR/
no ceilings. few cumulonimbus clouds. La Romana: VFR/no ceilings.
Punta Cana: VFR/no ceilings. few cumulonimbus clouds. Santiago;
VFR. few cumulonimbus clouds. ceiling at 8000 feet. Punta Cana:
VFR. ceiling at 7000 feet.

The GFS MODEL forecast for 250 MB shows that an anticyclonic
circulation center will move from the Yucatan Peninsula into the
NW corner of the Caribbean Sea, during day one. Expect NW wind
flow during day two. The GFS MODEL forecast for 500 MB shows that
anticyclonic wind flow will be present across Hispaniola during
day one. Expect NW and N wind flow across the area during day two.
An anticyclonic circulation center will form in the area that is
between the Cayman Islands, SE Cuba, and Jamaica. The GFS MODEL
forecast for 700 mb shows that S wind flow, with an east-to-west
oriented ridge, will move across the during the first half of day
one. Expect anticyclonic wind flow across the area during the
second half of day one, with a separate anticyclonic circulation
center. More anticyclonic wind flow will move across the area from
the second half of day one into the middle of day two. The second
half of day two will consist of N-to-NE wind flow, in a large-
scale ridge, whose anticyclonic wind flow is forecast to cover
parts of the Gulf of Mexico, the Caribbean Sea, and the Atlantic
Ocean.

...THE ATLANTIC OCEAN...

Upper level cyclonic wind flow covers the area from 20N northward
from 50W westward. An upper level trough that is in the area is
supporting a cold front that passes through 32N58W to a 1010 mb
low pressure center that is near 28N60W. A cold front continues
from the 1010 mb low center, to 25N62W, 23N70W, and 22N79W in
Cuba. Convective precipitation: in the Atlantic Ocean and in the
Caribbean Sea: widely scattered moderate to isolated strong from
22N northward between 50W and 60W, from 19N to 22N between 64W and
the Windward Passage including off the NE coast of Hispaniola, and
in the Caribbean Sea from 16N to 20N between 66W and 71W.
Rainshowers are possible elsewhere in the Atlantic Ocean from 20N
between 50W and 70W.

An upper level cyclonic circulation center is near 22N34W. Upper
level cyclonic wind flow covers the area from 18N northward
between Africa and 45W. Convective precipitation: rainshowers are
possible in the area of upper level cyclonic wind flow. Surface
anticyclonic wind flow covers the Atlantic Ocean from 20N
northward between Africa and 50W.

Upper level cyclonic wind flow and a trough have moved into
Africa mostly. Some residual deep layer cyclonic wind flow remains
from 15N northward and from 20W eastward. A surface trough is
along 31N10W to 28N18W to 25N17W. Rainshowers are possible from
17N northward from 20W eastward.

A central Atlantic Ocean surface ridge is along 20N50W to 27N45W
beyond 32N43W. A second surface ridge is in the eastern Atlantic
Ocean, from the Cabo Verde Islands to beyond 32N26W.

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

$$
MT


...ITCZ/MONSOON TROUGH...

The monsoon trough axis extends across Africa into the east
Tropical Atlantic near 12N16W to 07N22W. The intertropical
convergence zone axis extends from 07N22W to 05N40W to 10N60W.
Scattered moderate and isolated strong convection is within 180 nm
northeast of the axis between 40W and 50W. Scattered moderate
convection is within 180 nm north of the axis west of 55W.

...DISCUSSION...

...GULF OF MEXICO...

West-southwesterly flow aloft prevails over the Gulf early this
evening between upper level ridging extending from the southeast
Gulf to the southwest Gulf, and a broad middle to upper level low
approaching the Texas panhandle from the west-northwest. Moisture
and cloudiness continues to stream northeastward across northeast
and central Mexico, then across the Gulf northwest of the upper
ridging. Scattered to numerous showers and isolated thunderstorms
are likely across the same area of the upper level moisture, with
mainly dry conditions southeast of the upper ridging. A stationary
front extends from the central Gulf near 25N90W to 24.5N94W to
1016 mb low pressure near 22N96W to the coast of southeast Mexico
near 18N94W. Fresh to near gale force winds are reported within
150 nm north and northwest of the stationary front, while mainly
gentle to moderate easterly flow is found elsewhere across the
basin. The front will linger through Saturday, eventually merging
with a new front which is described in the special features
section above.

CARIBBEAN SEA...
Southerly upper level flow continues across much of the Caribbean
basin early this evening, except westerly over the waters north of
15N, around an upper level anticyclone over northern South
America. This flow is advecting middle to upper level moisture
from the deep tropics to the north. Very heavy rainfall is likely
occurring from western Colombia to across Costa Rica and Panama,
as well as portions of Nicaragua. Water vapor satellite imagery
indicates relatively dry air aloft north of 15N as a middle to
upper level trough extends into the northwest Caribbean from
22N80W to the Gulf of Honduras. At the surface, a trough, which
has the characteristics of a tropical wave, extends from the
southern coast of the Dominican Republic to 1011 mb low pressure
near 15N72W to 13N73W. Mainly moderate trades are observed across
the basin, except locally fresh across the approach to the
Windward Passage. The trough and low are forecast to dissipate
through Saturday as they drift westward. Winds will increase
locally to strong across the approach to the Windward Passage by
late Saturday night, with little change otherwise.

...HISPANIOLA...
A few isolated showers and thunderstorms developed over the Island
during the afternoon hours as a middle to upper level trough nears
the area from the west-northwest, supporting a surface trough
which extends toward the north coast of the island from the
northeast. Convection will likely diminish through the evening
with the loss of daytime heating, with isolated activity likely to
develop again on Saturday with a similar weather pattern in place.

ATLANTIC OCEAN...
A middle to upper level trough extends across the southwest north
Atlantic, extending from a vigorous upper level low centered well
north of the discussion area near 39N57W, southward through
25N60W, then southwest toward eastern Cuba. Very dry and stable
air continues to fill in behind this upper feature, which is
supporting a surface cold front extending from 32N54W to the
southeast Bahamas. Numerous showers and scattered thunderstorms
are occurring within 210 nm north of 24N ahead of the front.
Surface high pressure is building in behind the front with a west
to east ridge axis oscillating between 25N and 27N. The eastern
portion of the trough will continue to progress eastward, while
the western portion dissipates through early Saturday. A new cold
front will move into the northwest waters off of the southeast
U.S. coast Saturday night, stalling along 30N or 31N into Sunday
as high pressure ridging blocks further progress of the front. The
remainder of the basin is under the influence of a surface ridge,
anchored by a nearly stationary 1030 mb high centered southeast of
the Azores near 36N23W.

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

$$
MT
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