[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 151812
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
212 PM EDT Thu Jun 15 2017

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 1200 UTC surface analysis and satellite imagery through
1715 UTC.

...TROPICAL WAVES...

A strong tropical wave has been added to the 1200 UTC surface map
near the west coast of Africa based on visible satellite imagery
and the Hovmoller Diagram, that shows very well the westward
propagation of the wave. Its axis extends from 12N15W to 04N15W. A
cluster of moderate to strong convection is along the wave axis
from 06N to 09N between 13W and 17W. Scattered moderate to
isolated strong convection is noted elsewhere from 03N to 10N
between 12W and 19W.

A tropical wave located several hundred miles south-southwest of
the Cabo Verde Islands extends from 10N30W to a 1012 mb low
pressure located near 06N30W to 02N30W. This wave is producing
disorganized showers and thunderstorms, covering the area from
04N to 09N between 28W and 32W. Development, if any, of this
system should be slow to occur during the next few days while the
wave moves westward near 20 kt over the tropical Atlantic.

The tropical wave situated along 39W on the 1200 UTC surface map
is re-located farther east along 37W based on a recent ASCAT pass
that indicates the wind shift associated with the wave axis. Now,
the wave extends from 15N37W to 06N37W moving westward at around
10 kt. The wave remains embedded within an area of deep-layer
moisture as depicted on the TPW product. The wave also coincides
with an inverted trough at 700 mb. Satellite imagery shows a
cluster of moderate to isolated strong convection with some
cyclonic turning covering the area from 10N to 12.5N between 35W
and 40W. this wave is forecast to cross 55W Saturday night, and
move across the Windward Islands Sunday night.

A tropical wave is over the eastern Caribbean and extends from
Puerto Rico to the coast of central Venezuela. Convection is
limited in association with this wave, that could enhance some
shower and thunderstorm activity over Puerto Rico this afternoon
and early evening. The wave is very well depicted in the moisture
product and 700 streamline analysis. This wave is forecast to move
across Hispaniola late today through Friday.

Another tropical wave is drifting westward across the SW Caribbean
with axis from 17N81W to the coast of western Panama. Scattered
moderate convection is seen on either side of the wave axis covering
the waters from 13N to 17N between 77W and 84W, and south of 12N
west of 79W. This wave will reach central America tonight, and
will be absorbed by the complex low pressure system forecast to
develop over the northwestern Caribbean Sea and the Yucatan
Peninsula this weekend.

...MONSOON TROUGH/ITCZ...

The Monsoon Trough extends from the coast of west Africa near
10N14W to 07N20W to 07N28W. The ITCZ extends from 06N31W to
09N39W to 08N50W to 07N58W. Three tropical waves are embedded
within the Monsoon trough/ITCZ. Most of the convective activity
is associated with these tropical waves.

...DISCUSSION...

GULF OF MEXICO...

A ridge extends from the western Atlantic, across Florida into
the Gulf of Mexico producing gentle to moderate E to SE winds
across the area. A thermal trough, that normally develops during
the evening hours over the Yucatan Peninsula and moves across the
SW Gulf during the overnight and early morning hours, extends
along 94W south of 22N. Water vapor imagery continues to reveal
the presence of an upper-level low spinning over the SE Gulf, with
a trough extending SW across the northern Yucatan Peninsula into
the eastern Bay of Campeche. A few showers are associated with
the upper-low. Upper diffluence on the east side of the low
combined with a moist and humid SE flow at low levels, will
continue to support the development of showers and thunderstorms
over parts of south and central Florida, the Florida Keys and the
SE Gulf. Abundant moisture is expected to persist over the SE
Gulf and the Yucatan Peninsula through the weekend. This weather
pattern will be associated with a complex area of low pressure
forecast to form over the northwestern Caribbean Sea and the
Yucatan Peninsula this weekend. Conditions appear to be favorable
for gradual development of this system while it moves slowly
northwestward toward the southern Gulf of Mexico by early next
week.

CARIBBEAN SEA...

Two tropical waves are moving across the Caribbean Sea. Please
see the tropical waves section for more details. These tropical
waves will become absorbed in a broad area of low pressure
forecast to form over the NW Caribbean during the upcoming weekend.
Scatterometer data show moderate to fresh trades across the east
and central Caribbean. Gentle to moderate winds are seen over the
NW Caribbean. This wind pattern will continue through Saturday.
Looking ahead, a broad area of low pressure is expected to form
over the northwestern Caribbean Sea and adjacent land areas by the
weekend. Experimental GOES-16 visible satellite imagery hints the
presence of a low level circulation over eastern Honduras. This
system will bring increasing winds and building seas across the
central and western Caribbean during the upcoming weekend due to a
tight pressure gradient between the developing low pressure and
the Atlantic ridge. Plenty of moisture and very active weather is
also expected with this low, likely affecting the western and
central Caribbean Sea, Central America, and most of Cuba during
the weekend. Locally heavy rain could occur over parts of Cuba,
the Yucatan Peninsula and Central America.

...HISPANIOLA...

A tropical wave, currently over Puerto Rico, will move across
Hispaniola late today through Friday supporting scattered showers
and tstms mainly in the afternoon and evening hours.

ATLANTIC OCEAN...

Three tropical waves are moving westward between the coast of
Africa and the Lesser Antilles. Please refer to the Tropical Waves
section above for details. A surface trough extends from 31N55W
to 25N64W. This trough is a reflection of an upper-level low
located near 29N58W, with a trough extending SW toward Puerto
Rico. Scattered showers and thunderstorm are noted within about
180 nm SE of the trough axis. A weak low may develop along the
trough axis on Friday. Otherwise, broad high pressure covers the
Atlantic from the Azores to the Florida Peninsula. Moderate to
locally fresh trades are around the southern periphery of the
ridge between the Windward Islands and the coast of Africa. A
surge of African dust continues to spread westward in the wake of
the tropical wave located along 37W as noted in the Saharan Air
Layer from CIMSS.

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

$$
GR
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