[Tropical] Tropical Weather Discussion

EMWIN Server emwin at nashvilleweather.net
Wed Aug 30 01:07:15 CDT 2017


AXNT20 KNHC 300607
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
206 AM EDT Wed Aug 30 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 0000 UTC surface analysis and satellite imagery through
0500 UTC.

...SPECIAL FEATURES...

Tropical Storm Harvey is centered near 29.2N 93.5W at 30/0600 UTC
or about 40 nm SSW of Cameron Louisiana and 45 nm SSE of Port
Arthur, Texas moving NE at 7 kt. Estimated minimum central
pressure is 995 mb. Maximum sustained wind speed is 40 kt with
gusts to 50 kt. Associated deep convection is displaced NNW of the
center over the extreme NE Texas and extreme SW Louisiana coasts
near the Sabine River. Feeder bands east of the center continue to
produce isolated moderate convection over the north central Gulf
N of 28N between 86W and 90W. Coastal areas of Louisiana,
Mississippi, Alabama and the western Florida panhandle are also
included in this area. See latest Intermediate Public Advisory
under AWIPS/WMO headers MIATCPAT4/WTNT34 KNHC and the full
Forecast/Advisory under AWIPS/WMO headers MIATCMAT4/WTNT24 KNHC
for more details.

A tropical wave is over the E Atlantic associated with a 1008 mb
low that is located near 16N27W. The wave axis extends from
23N25W to the low to 10N27W, moving W at 15-20 kt. Numerous
moderate and scattered strong convection is found from 15N to 19N
between 26W and 32W. Scattered moderate convection is occurring
from 07N to 12N between 26W and 40W. A recent scatterometer pass
indicated 20-25 KT winds within 180 nm in the N semicircle of the
low. The wave is embedded in an area of deep layer moisture as
seen on TPW satellite imagery. This system has become better
organized since yesterday, and a tropical depression could form
from this system over the eastern Atlantic during the next couple
of days. Heavy rain is possible over portions of the northwestern
Cabo Verde Islands for a few more hours. There is now a high
chance for this system to become a tropical cyclone during the
next 48 hours.

...TROPICAL WAVES...

A tropical wave over the central Atlantic has an axis extending
from 24N44W to 10N43W, moving W at 10-15 kt. The wave coincides
with an amplified 700 mb trough in initial model wind fields. TPW
satellite imagery shows an area of modest deep layer moisture
located on the east side of the wave. Satellite imagery also shows
the presence of a large area of Saharan dust to the N and W of
the wave. Scattered moderate and isolated strong convection is
present from 08N to 10N between 40W and 45W.

A tropical wave over the E Caribbean extends from 22N69W to
10N71W moving W at 15 to 20 kt. The wave coincides with modest 700
mb troughing in initial model wind fields and curvature of low-
level winds in the most recent scatterometer pass. SSMI TPW
imagery shows this wave is embedded in an area of modest deep
layer moisture. This wave is triggering isolated thunderstorms
over Hispaniola.

A tropical wave over the W Caribbean extends from 21N84W to
09N83W, moving W at 15 kt. The wave coincides with subtle 700 mb
troughing in initial model wind fields. TPW satellite imagery
shows this wave is embedded in an area of modest deep layer
moisture. This wave is producing isolated thunderstorms along the
east coast of Nicaragua.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from 18N16W to low pres 1008 mb
centered near 16N27W to 10N50W. The ITCZ continues from 10N50W to
09N61W. Besides the convection associated with the tropical
waves, scattered moderate convection is from 07N to 09N between
35W and 40W and from 11N to 13N between 56W and 61W, to include
portions of the Windward Islands.

...DISCUSSION...

GULF OF MEXICO...

Tropical Storm Harvey has a low-level exposed center located over
the Gulf of Mexico near 29N94W. Associated deep convection is
displaced NNW of the center over the extreme NE Texas and extreme
SW Louisiana coasts near the Sabine River. Feeder bands east of
the center continue to produce isolated moderate convection over
the north central Gulf N of 28N between 86W and 90W. Coastal areas
of Louisiana, Mississippi, Alabama and the western Florida
panhandle are also included in this area. Catastrophic inland
flooding is forecast to continue over Texas and Louisiana during
the next few days. Of interest, a preliminary report from a Texas
rain gauge has broken the Texas tropical cyclone rainfall record.
An upper-level trough extends southward through Oklahoma and
Texas. Divergent upper level winds east of the trough axis are
aiding convection over the Gulf of Mexico and Florida N of 26N.
Harvey is expected to move slowly NE and move inland over SW
Louisiana this morning and reach NE Louisiana Thursday morning.

CARIBBEAN SEA...

Two tropical waves are moving across the Caribbean waters. See
the tropical waves section for additional details. The eastern
portion of the E Pacific monsoon trough passes over Costa Rica
and Panama. Low-level convergence near the trough is producing
scattered moderate and isolated strong convection over Costa Rica
and Panama. In the upper levels, an upper level low centered over
the Yucatan Peninsula near 21N88W is enhancing showers over the
Yucatan and Central America.

...HISPANIOLA...

Isolated showers and thunderstorms are occurring over the island
due to a tropical wave. Expect similar conditions during the next
day or so until the wave moves farther west.


ATLANTIC OCEAN...

A broad 1028 mb high centered over the Azores near 39N27W ridges
SW to another weaker 1020 mb high centered near 27N57W then to
the southeastern Gulf of Mexico. Moderate to locally fresh trade
winds prevail south of the ridge to the west of 30W.

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

$$
McElroy
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