[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 202352
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
705 PM EST TUE DEC 20 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...

.None.

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

The Monsoon Trough extends sw off the coast of Africa at 06N11W
to 05N14W where scatterometer winds indicate a transition to an
ITCZ axis, which continues sw to 01N27W, then turns nw to 03N42W
where it loses identity. Scattered moderate isolated strong
convection is noted from the equator to 05N between 20W and 37W.


...DISCUSSION...

...THE GULF OF MEXICO...

Nearly zonal mid to upper level flow is observed across most of
the Gulf of Mexico.  To the lower levels a stationary front
extends sw from Tampa Bay through 23N93W to the s-central Bay of
Campeche. Strong to near gale force northwesterly winds will
continue s of 25N to the sw of the decaying front this evening,
then mostly strong nw winds are expected late tonight through
midday Wed when the remnants of the front will become orientated
from nw to se along a position from 23N97W to 19N93W where it
meander for a few days.  Fresh to locally strong ne winds should
develop along the nw coast of the Yucatan Peninsula tonight.
Otherwise broken to locally overcast low to to mid level clouds
are observed to the n of the front with elevated platforms in
the n-central gulf reporting reduced visibility in fog and low-
level stratus.
...THE CARIBBEAN SEA...

A tight pressure gradient between Atlantic high pressure and
lower pressure over Colombia will support near gale force winds
along the nw coast of Colombia tonight into Wed, and fresh to
locally strong ne to e winds are expected elsewhere to the n of
11N between 70W and 87W. Combined seas of 8 to 13 ft are
forecast in the resultant ne-e swell. An area of broken low to
mid level clouds, with scattered showers and even a few
thunderstorms detected by lightning data, is observed to the e
of 70W.  The heaviest clusters are passing w across the Mona
Passage and onshore the Dominican Republic at the moment.   This
convective activity will likely continue to shift w with time as
the supporting upper trough is forecast to shift w across the
central Caribbean through Wed.  Subsidence associated with an
upper ridge is suppressing convection across the western
Caribbean.

...HISPANIOLA...

A sharp transition line between deep moisture and pronounced
drying subsidence is currently orientated n to s along 69W.  The
line will shift w tonight into Wed allowing showers along the e
coast to spread w across the central and western portions of the
Dominican Republic, and possibly reach eastern Haiti late Wed.

...THE ATLANTIC OCEAN...

A 1021 mb surface low is analyzed at 32.5N74W and trails a  cold
front sw to Central Florida.  The northern segment of the cold
front will continue e tonight and stall from Bermuda to Central
Florida on Wed night and Thu.  The front will move e again on
Thu night and Fri with high pressure building in its wake.
Broken to overcast low and mid level clouds with embedded
accompany the front and are also noted across the Straits of
Florida.

An upper level trough dissects the s-central n Atlc from 32N53W
to 19N70W. Upper diffluence e of the trough is supporting
large areas of broken lo-mid level clouds and embedded showers
and thunderstorms all within 150 nm either side of a line from
25N46W to the Mona Passage. This activity will shift w tonight
and Wed as the supporting upper trough shifts w.   Dense cirriform
clouds are streaming ene from South America to Africa within
300 nm either side of a line from 06N55W to 20N17W.

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

$$
Nelson
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