[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 291759
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
159 PM EDT Tue Aug 29 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.

...SPECIAL FEATURES...

Tropical Storm Harvey is centered near 28.8N 94.3W at 29/1800 UTC
or about 70 nm SSW of Port Arthur, Texas moving NNE at 6 kt.
Estimated minimum central pressure is 997 mb. Maximum sustained
wind speed is 40 kt with gusts to 50 kt. Numerous moderate to
strong convection is present within 90 NM in the N quadrant of the
center over the upper Texas and extreme western Louisiana coasts.
WSR-88D from Houston, TX indicated very heavy rainfall from the
Sabine River to High Island, TX extending over the Houston metro
area. A stationary front lies along the Gulf coast and extends to
near the circulation of Harvey. A surface trough curves south from
the center to 21N94W. Scattered moderate and strong convection is
occurring within 45-60 NM E of the trough. 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.

Potential Tropical Cyclone Ten is centered near 35.3N 75.8W at
29/1800 UTC or about 15 nm WNW of Cape Hatteras North Carolina
moving NE at 18 kt. Estimated minimum central pressure is 1006
mb. Maximum sustained winds are 35 kt with gusts to 45 kt.
Scattered to numerous moderate to strong convection was well
displaced from the low level center and within 180 NM in the E
quadrant of the low over the Gulf Stream off the NC coast. The
system will exit the northern Outer Banks within the next few
hours and intensify primarily as an extra-tropical cyclone over
the open North Atlantic well to the S of New England on Wed. See
latest Intermediate Public Advisory under AWIPS/WMO headers
MIATCPAT5/ WTNT35 KNHC and the full Forecast/Advisory under
AWIPS/WMO headers MIATCMAT5/WTNT25 KNHC for more details.

A tropical wave is over the E Atlantic associated with a 1010 mb
low that is located near 15N24W. The wave axis extends from
20N25W to the low to 06N22W, moving W at 15 to 20 kt. Numerous
moderate and isolated strong convection is observed from 14N to
17N between 23W and 26W. Scattered moderate to strong convection
was noted within 240 NM in the NW semicircle of the low. 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. Regardless of development, heavy rain is
possible in portions of the Cabo Verde Islands through Wednesday.
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 24N41W to 11N38W, moving W at 10 to 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. Convection associated with the wave is limited
at this time.

A tropical wave over the E Caribbean has been relocated slightly
to the east and now extends from 22N66W to 11N68W moving W at 15
to 20 kt. The wave coincides with modest 700 mb troughing in
initial model wind fields and curvature in the most recent
scatterometer pass. SSMI TPW imagery shows this wave is embedded
in an area of modest deep layer moisture. Widely scattered
thunderstorms are occurring within 90 nm of the wave axis N of 15N
extending over portions of Puerto Rico and Hispaniola.

A tropical wave over the west central Caribbean extends from
20N80W to 10N82W, moving W around 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. Scattered thunderstorms are occurring within
90 nm of the wave axis along the coast of Costa Rica.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from Mauritania in west Africa near
19N16W to low pres 1008 mb near 15N24W to 13N35W to 09N48W. The
ITCZ continues from 09N48W to 08N58W. Other than the convection
associated with the tropical waves, there is no significant
convection associated with either the monsoon trough or ITCZ.

...DISCUSSION...

GULF OF MEXICO...

Tropical Storm Harvey has a fairly broad low-level exposed center
located over the Gulf of Mexico near 28N95W. Associated deep
convection is displaced NE of the center over the upper Texas
and extreme SW Louisiana coasts. Feeder bands on the east side of
a surface trough extending S from Harvey to 21N94W continue to
produce isolated moderate convection over the north central Gulf,
Louisiana, Mississippi, Alabama and the western Florida panhandle.
Catastrophic inland flooding is forecast to continue over Texas
and Louisiana over the next few days. Of interest, a preliminary
report from a Texas rain gauge has broken the Texas tropical
cyclone rainfall record. Mary's Creek at Winding Road southeast of
Houston reported 49.20 inches in a time period ranging from 12:00
AM CDT August 25 to 9:20 AM CDT August 29. A stationary front
lies along the Gulf coast and extends to near the circulation of
Harvey. Another surface trough traverses N Florida and the NE
Gulf from 32N78W to 28N88W. Divergent upper level winds are
located east of the trough axis over the Gulf of Mexico and
Florida N of 26N. Harvey is expected to drift slowly NE along the
middle and upper coasts of Texas through Tuesday night, then move
inland over SW Louisiana on Wednesday.

CARIBBEAN SEA...

Two tropical waves are moving across the Caribbean waters. See
the tropical waves section for additional details. The eastern
terminus of the E Pacific monsoon trough passes over Costa Rica,
and Panama and producing scattered moderate and isolated strong
convection over the Caribbean S of 13N and W of 76W. In the upper
levels, an upper level low is centered over the Gulf of Honduras
near 17N86W enhancing showers over the Yucatan and Central
America.

...HISPANIOLA...

Showers and thunderstorms are increasing over the eastern half of
the Dominican Republic in advance of the tropical wave moving
across the Mona Passage. The 1200 UTC rawindsonde from Santo
Domingo showed moisture up to 600 mb with precipitable water
values of close to 2 inches. As the tropical wave moves further
west expect increasing showers and thunderstorm over the island on
Wed with possible localized flooding.

ATLANTIC OCEAN...

Potential Tropical Cyclone Ten is centered N of the area near
35.3N 75.8W. This system continues to impact the northwestern
portion of the discussion area N of 29N with convection, 20 to 25
kt winds and seas to 9 ft. For additional information please see
Special Features section above. Elsewhere, a broad 1028 mb high
centered over the Azores near 40N28W ridges SW to another weaker
1020 mb high near 28N55W then to the central Bahamas. Moderate to
locally fresh trade winds prevail south of the ridge west of 30W.

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

$$
Cobb
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