[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 200007
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
707 PM EST MON DEC 19 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 1800 UTC surface analysis and satellite imagery through
2315 UTC.

...SPECIAL FEATURES...

..GULF OF MEXICO GALE WARNING...

A stationary front extends from 30N84W through 24N93W to 18N94W.
Gale force winds of 30 to 40 kt are occurring S of 23N and W of
the front with seas of 10 to 17 FT. The gale force winds are
forecast to continue for the next 24 hours or so. Please read the
Atlantic high seas forecast, that is listed under AWIPS/WMO
headers MIAHSFAT2/FZNT02 KNHC, for more details about each area of
gale-force winds.

...CARIBBEAN SEA GALE WARNING...

A tight pressure gradient between high pressure building in the
Atlantic Ocean, to the north of the Caribbean Sea, and lower
pressure that is associated with climatologically lower surface
pressure in Colombia has resulted in gale-force winds and seas of
11 to 14 FT in an area from 11N to 12.5N between 74W and 76W, off
the coast of Colombia. The gale-force winds are forecast to
continue for the next 18 hours or so...then decrease to 20 to 30
KT. Please read the Atlantic high seas forecast, that is listed
under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC, for more details.

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

The Monsoon Trough extends from the coast of Africa near 07N11W
to 03N17W. The ITCZ continues from 03N17W to 03N30W to the coast
of Brazil near 02N50W. Scattered moderate isolated strong
convection was noted from the equator to 03N between 34W and 43W.
Isolated moderate convection was noted elsewhere from 04N to 08N
between 50W and 58W.

...DISCUSSION...

...THE GULF OF MEXICO...

Broad mid to upper level WSW flow spans the entire Gulf of
Mexico with water vapor imagery depicting a belt of mid to upper
level moisture over the NW half of the Gulf while moderate
subsidence prevails over the SE half. At the surface, a stationary
front extends from 30N84W through 24N93W to 18N94W. Strong
northerly winds are occurring over most of the Gulf north of the
front. Please refer to the SPECIAL FEATURES section for
information about gale-force winds and seas S of 23N. Widely
scattered moderate, but weakening convection was noted within
45 to 60 NM of 25N88W and 22N93W. Broken to overcast low clouds
with possible embedded rainshowers were noted elsewhere northwest
of the front. Winds and seas will gradually subside over most of
the Gulf on Tue with strong to near0-gale force winds remaining
along the coast of Mexico S of 20N.

...THE CARIBBEAN SEA...

An upper level ridge dominates the Caribbean W of 80W. A fairly
large cyclonic circulation centered near Puerto Rico was moving
WSW toward the NE Caribbean. Cyclonic W to NW flow prevailed ahead
of the circulation over most of the Caribbean E of 80W within an
broad area of moderate to strong subsidence. At the surface fresh
to strong trade winds prevailed over most of the basin E of 80W
with gale force winds noted near the coast of Colombia. Please
refer to the SPECIAL FEATURES section for information about this
area of gale-force winds. Patches of broken trade wind cumulus
were noted in the area of strong winds with isolated showers,
especially just to the SE of Puerto Rico, from 15N to 16N between
67W and 70W, and to the west of the line 14N81W 19N84W.

...HISPANIOLA...

Moderate upper level NE winds are noted across Hispaniola with
pronounced subsidence over the region. The 12Z rawindsonde from
Santo Domingo indicated a very dry airmass accompanied by a strong
trade wind inversion. The precipitable water was only 1.23 inches.
Strong winds of 35 KT were noted above the inversion layer at
around 930 MB. Given this only patches of low clouds were notedover
the island with possible showers in orographically favored areas.
Little change is anticipated into Tue.

...THE ATLANTIC OCEAN...

A stationary front extends from 32N36W to 31N30W and transitions
to a surface trough at 31N30W and continues through 28N45W to
28N55W. Broken to overcast low and mid level clouds with embedded
showers were noted within 150 nm to the S of the trough between
40W and 50W.

An upper level trough passes through 32N10W, to 24N33W 14N48W
and 12N52W. No significant deep convective precipitation is
apparent in satellite imagery.

A surface ridge passes through Bermuda, to 28N75W, across the
southern part of Florida, to the far southeastern Gulf of Mexico.
A stationary front was over the far NW portion of the area.

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

$$
Cobb
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