[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 041821
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
221 PM EDT Tue Jul 4 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
1700 UTC.

...SPECIAL FEATURES...

A 1009 mb surface low is centered near 10N34W. Scattered moderate
and isolated strong convection is located in the northeast and
southwest quadrants of the low within 360 nm of the center. The
low is surrounded by a large area of cyclonic winds extending
about 400 nm from the center. The latest satellite-derived wind
data shows peak winds of near gale force in the southeastern
quadrant. The low is expected to move slowly W today, then move
toward the WNW at 10 to 15 mph tonight and Wednesday. The system
retains a high chance of becoming a tropical cyclone during the
next 48 hours.

...TROPICAL WAVES...

A tropical wave over the eastern Atlantic has an axis extending
from 07N32W to 18N32W, moving west at about 20 kt during the last
24 hours. The wave is embedded in a moist monsoonal flow, as seen
in the Total Precipitable Water imagery, and extends across the
monsoon trough. This wave is reflected by a surface trough in
satellite derived wind data as well as initial model 700 mb wind
fields. No significant deep convection is occurring in association
with this wave.

A tropical wave over the central Atlantic has an axis extending
from 08N44W to 20N39W, moving west at about 20 kt during the last
24 hours. This wave had spun off the surface low currently to the
east of the wave axis. The convection formerly associated with
this wave has consolidated around the surface low. This low is
described in the Special Features section. The wave exhibits a
modest signature in initial model 700 mb wind fields.

A tropical wave located over the far eastern Caribbean has an
axis reaching from 10N65W to 21N62W, moving west at around 15 kt
during the past 24 hours. Satellite-derived wind data and surface
station observations both show the wave has a well defined surface
trough. The wave has scattered moderate and isolated convection
from 19N to 21N between 60W and 63W.

A tropical wave over the western Caribbean has an axis running
from 10N80W to 19N80W. The wave is moving westward at about 20 kt.
The wave only exhibits subtle troughing in surface observations
and initial 700 mb model fields. Scattered moderate and isolated
strong convection is present within 120 nm either side of a line
from 13N79W to 18N86W.

...ITCZ/MONSOON TROUGH...

The Monsoon Trough axis extends from Senegal on the west coast of
Africa near 14N16W to low pres 1009 mb near 10N34W to 08N42W. The
Intertropical Convergence Zone extends from 09N46W to just N of
the coast of Suriname near 07N55W. Convection observed near the
Monsoon Trough and ITCZ is associated with tropical waves and the
surface low. Refer to the Tropical Waves and Special Features
sections above for details. Otherwise, widely scattered moderate
convection is located from 05N to 09N between 10W and 18W.

...DISCUSSION...

GULF OF MEXICO...

Weak surface ridging crosses the northern Gulf from central
Florida to the Texas Coastal Bend. A weak surface trough extends
into northern Florida from 29N85W. No deep convection is currently
associated with this trough. Winds over the Gulf generally run
between 10 and 20 kt across the Gulf. Easterlies over the eastern
Gulf veering to southeasterlies over the western Gulf. Little
change in this pattern is expected during the next couple of days.

CARIBBEAN SEA...

The moderate pressure gradient over the Caribbean between the
Bermuda high to the north and the Colombia low to the south is
maintaining moderate to fresh tradewinds over the basin. The
exception is fresh to strong easterlies north of Colombia and
Venezuela. Convection over the SW Caribbean in the vicinity of
Honduras and Nicaragua appears to be associated with with the
eastern extension of the NE Pacific monsoon trough and a tropical
wave mentioned in the Tropical Waves section. Water vapor
satellite imagery indicates an upper-level low is centered over
the NW Caribbean just S of Cuba near 21N79W. This low is
interacting with the tropical wave to trigger convection over the
western Caribbean. The upper-level low is expected to weaken and
move NW by Thu, which should allow convection in this area to
decrease.

...HISPANIOLA...

Currently there is no deep convection over Hispaniola as an
upper- level ridge resides overhead. Expect convection to increase
on Wednesday as the moisture associated with the wave over the
Lesser Antilles arrives.

ATLANTIC OCEAN...

Two tropical waves are analyzed over the basin. Refer to the
Tropical Waves section above for details. Also a surface low is
described in the Special Features section. A large 1030 mb high is
centered SW of the Azores near 35N41W. The high continues to
dominate the weather across the tropical north Atlantic. To the
south of the high and away from the surface low described above,
moderate to fresh trade winds prevail across the basin. This
synoptic pattern will change little through Wednesday night.

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

$$
McElroy
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