[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 240004
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
804 PM EDT Fri Mar 23 2018

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
2300 UTC.

...SPECIAL FEATURES...

...GALE WARNING FOR THE SOUTH-CENTRAL CARIBBEAN SEA...

A combination of strong surface high pressure ridging southward
along the U.S. east coast and relatively strong low pressure over
northern South America is expected to support winds to gale force
near the coast of Colombia beginning this evening. The gale force
winds will not be continuous but are expected to recur each night
during the evening and overnight hours through the end of next
week while this surface weather pattern persists. For more details
please see High Seas Forecasts issued by the National Weather
Service under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC. This
information can also be found at the following website:
www.nhc.noaa.gov/marine

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from Sierra Leone on the African coast
near 08N13W to 04N19W. The ITCZ continues from 04N19W to 01N31W
to the northeast coast of Brazil near 03S45W. Scattered moderate
and isolated strong convection is present from 02N to 05N between
07W and 20W. Similar convection is occurring from 03S to 00N
between 38W and 44W.

...DISCUSSION...

GULF OF MEXICO...

Fair weather prevails across the entire Gulf of Mexico due to the
combination of surface high pressure, supported by a 1028 mb high
near the Florida-Georgia border, and abundant dry air in the mid-
and upper-levels of the atmosphere. The surface winds are out of
the northeast to east over the eastern and central Gulf and east
to southeast over the western Gulf. The winds are strongest over
the southern and western waters, but they are generally less than
20 kt area-wide. Sea heights are highest, near 6 ft, in the Bay
of Campeche due to the longer fetch there. Surface high pressure
is expected to gradually shift southeastward this weekend, causing
winds to turn southerly over much of the region. This flow will
cause sea heights to increase a little over the northwestern
waters. Fair weather is expected to continue through the weekend
as dry air remains in place.


CARIBBEAN SEA...

Undersea volcano Kick'em Jenny, north of Grenada near 12.18N
61.38W, is in a state of unrest. The government of Grenada advises
mariners to observe a 5 km or 3.1 nm exclusion zone around
Kick'em Jenny. Please refer to the web page, www.nadma.gd, for
additional information.

Tranquil conditions exist across the Caribbean Sea today with
satellite images merely showing the typical patches of low clouds
and embedded quick-moving showers across the region. The remnants
of a cold front from the Windward Passage to northeastern
Nicaragua is marked by a wind shift with northeasterly to
northerly winds west of that line and easterly flow to the east of
that old boundary. Trade winds are strongest over the south-
central waters near the coast of Colombia, and these winds are
expected to reach gale force during the evening and overnight
hours through Thu night and Fri morning. See the SPECIAL FEATURES
section above for more details. Looking ahead to the weekend, the
remnants of the cold front is expected to dissipate, leaving the
area in more uniform easterly flow and fair weather.

ATLANTIC OCEAN...

A stationary front enters the discussion area near 32N58W and
continues southwestward to 23N68W, then continues as a weakening
stationary front to the Windward Passage. Scattered showers and
isolated thunderstorms are observed along and up to 90 n mi SE of
the front N of 24N, while cloudiness and patchy rain are seen
along and up to 90 nm NW of this boundary N of 24N. West of the
front, surface high pressure dominates the area with northerly
flow and cooler air covering the western Atlantic. Strong surface
high pressure also dominates the central and eastern Atlantic
Ocean anchored by a 1034 mb high near 35N34W. This high is
producing fresh to strong trade wind flow across a large portion
of the tropical and subtropical eastern Atlantic waters. Despite
the surface high pressure, there is an area of showers and
thunderstorms from 16N to 18N between 31W and 39W associated with
an upper-level low.

The front over the central-western Atlantic is expected to slowly
shift eastward and weaken while another boundary enters the far
northwestern waters this weekend.

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

$$
McElroy
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