[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 191726
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
126 PM EDT Wed Jul 19 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
1745 UTC.

...TROPICAL WAVES...

A tropical wave is over the far eastern Atlantic with its axis
extending from near 15N20W to 06N21W moving westward 15-20 kt. The
wave remains embedded in a deep pool of moisture as seen in the
SSMI Total Precipitable Water imagery (TPW), and in the latest
CIRA low-mid level moisture imagery. The 700 mb streamlone
guidance from the GFS indicates a well-defined 700 mb broad trough
in the vicinity of the wave. Scattered moderate isolated strong
convection is east of the wave to the coast of Africa from 08N-
13N.

A large central Atlantic tropical wave with its axis extending
from near 22N41W to 15N43W to low pressure of 1012 mb on the wave
axis at 11.5N44W to 05N45W. This system is moving in a general
westward to west-northwestward direction at about 12 kt. The wave
continues to exhibit a very large envelop of cyclonic rotation as
observed in the low cloud motion. Latest satellite imagery shows
that there has been some increase in deep level moisture with
this sytem during the past several hours. Scattered moderate
convection is seen from 10N-12N between 44W-47W, and within 30 nm
of line from 16N40W to 17N41W. Acccording to the latest NHC
Tropical Weather Outlook some gradual development of this system
is possible during the next couple of days as it maintains its
current motion.

A tropical wave over the eastern Caribbean Sea has been introduced
to 12 UTC surface analysis. This wave denotes the remnants of
recent Tropical Storm Don. The wave is analyzed from near 16N66W
to a 1012 mb low to just north of Isla Margarita. The wave and low
are moving westward at 20-25 kt. Both Total Precipitable Water
imagery and satellite imagery depict the wave and low to be within
an area of very deep moisture south of 15N. Scattered showers and
isolated thunderstorms are within 180 nm east of the wave and
low. To the north of 15N, the atmosphere is very dry under a
Saharan Air Layer that has migrated westward over the eastern
Caribbean in the wake of the following wave described below. The
low pressure is forecast to dissipate in about 24 hours, while the
wave will continue through the rest of eastern Caribbean through
this evening, and the central Caribbean on Thursday. Fresh to
strong east winds will follow in the wake of the wave.

A tropical wave is across the central Caribbean along 72W
southward to inland Venezuela at  It is moving westward at about
20 kt. Similarly to the wave located to its east discussed above,
this wave is embedded within an area of very deep moisture south
of 15N, and is under Saharan Air Layer and dust north of 15N.
Latest satellite imagery shows scatered moderate isolated
convection moving quickly to the west behind the wave, and
consists of the scattered moderate to isolated type intensity
activity from 12N-14N between 66W and the wave. This activity
has the capability to produce strong gusty winds and very
rainfall. The visible imagery denotes the leading edge of
the convection as outlow boundaries racing westward along the
wave axis south of 15N.

...ITCZ/MONSOON TROUGH...

The monsoon trough axis extends from 12N16W to 07N25W to 12N41W
to 09N48W. The ITCZ then extends from 09N48W to 06N56W. Aside
from the convection associated with the tropical waves, scattered
moderate isolated strong convection is within 120 nm north of the
trough axis between 23W-27W.

...DISCUSSION...

GULF OF MEXICO...

In the upper levels, an upper level low lifting northward is
centered over Mexico near 23N98W. Upper level diffluence to the
southeast of the low is supporting scattered moderate convection
over the far western Gulf from 21N-24N west of 94W. This activity
will remain active through the rest of the afternoon and into
tonight. A mid/upper trough just inland the north and northeast
Gulf is helping to support scattered showers and thunderstorms
north of 27N between 86W and 91W. At the surface, the Yucatan
Peninsula thermal trough pushed westward to the central Bay of
Campeche last night, and extends from 21N93W to inland Mexico at
18N94W at 12 UTC. Scattered showers and isolated thunderstorms
within 180 nm either side of the trough. Elsewhere, a 1019 mb high
center is over the central Gulf at 26N88W. This feature remains
in control of the wind regime throughout, with the associated
gradient providing mainly gentle anticyclonic flow throughout.


CARIBBEAN SEA...

The main feature of concern for the SE Caribbean is the remnants
of Don moving across the Windward Islands, and a tropical wave
along 72W. Remnants of Don on 19/0900 UTC is centered near the
island of La Blanquilla at 12N64W, moving westward at 22 kt.
Estimated minimum central pressure is 1012 mb. Scattered moderate
convection is over the Windward Islands from 11N-13N between 63W-
68W. The remnants of Don is expected to produce total rain
accumulations of 3 to 6 inches. There remains a potential for
life-threatening flash floods and mudslides, along the coast of
Venezuela. In addition, scattered moderate to strong convection is
inland over SE Venezuela, and over N Colombia. Scattered moderate
to strong convection is over the SW Caribbean S of 11N.
Elsewhere, scattered showers and isolated thunderstorms are over
the NW Caribbean from 16N-21N between 79W-85W. Of note in the
upper levels, an upper level low is centered over E Cuba near
19N75W. Expect additional convection over the S Caribbean and
Central America over the next 24 hours.

...HISPANIOLA...

A fast moving tropical wave is supporting isolated showers
across the Dominican Republic and adjacent waters. The wave will
traverse the island today. Expect scattered thunderstorms over
the island during maximum heating today.

ATLANTIC OCEAN...

Scattered showers are over the N Bahamas and the W Atlantic, N of
25N and W of 73W. A large 1027 mb high is centered over the
central Atlantic near 32N57W producing fair weather. As typical
for this time of year, tropical waves are moving through the
tropical Atlantic waters. Of note in the upper levels, an upper
level high is over the W Atlantic near 33N66W producing upper
level diffluence over Florida. An upper level low is also centered
over the W Atlantic near 25N49W enhancing showers NW of center.

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

$$
Aguirre
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