[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 311805
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
205 PM EDT WED AUG 31 2016

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...The center of Hurricane Gaston at 31/1500
UTC is near 34.0N 48.6W, or about 1000 nm to the west of Faiala
Island in the central part of the Azores, and about 1075 nm to
the west of Lajes Air Base in the Azores. Gaston is moving east-
northeastward, 60 degrees, 8 knots. The estimated minimum
central pressure is 961 mb. The maximum sustained wind speeds
are 100 knots with gusts to 120 knots. Convective precipitation:
Scattered to numerous strong within 120 nm of the center in the
southern semicircle. Scattered moderate to isolated strong
within 180 nm of the center in the NE quadrant. Please read the
latest NHC Intermediate Public Advisory under AWIPS/WMO headers
MIATCPAT2/WTNT32 KNHC and the Forecast/Advisory under the
AWIPS/WMO headers MIATCMAT2/WTNT22 KNHC for more details.

The center of Tropical Depression Eight at 31/1500 UTC is near
35.5N 73.1W, or about 120 nm to the east of Cape Hatteras North
Carolina. The depression is moving northeastward, or 55 degrees,
13 knots. The estimated minimum central pressure is 1010 mb. The
maximum sustained wind speeds are 30 knots with gusts to 40
knots. Convective precipitation: Widely scattered moderate to
isolated strong within 60 nm to 180 nm of the center in the east
semicircle. Scattered moderate to strong is from 30N to 32N
between 77W and 79W. An upper level ridge extends from 28N83W in
the Gulf of Mexico, across Florida, to 29N78W in the Atlantic
Ocean, beyond 32N75W. Please read the latest NHC Intermediate
Public Advisory under AWIPS/WMO headers MIATCPAT3/WTNT33 KNHC
and the Forecast/Advisory under the AWIPS/WMO headers
MIATCMAT3/WTNT23 KNHC for more details.

Tropical Depression has developed into Tropical Storm Hermine.
The center of Tropical Storm Hermine at 31/1800 UTC is near
24.7N 88.0W, or about 345 nm south-southwest of Apalachicola
Florida and about 360 nm to the west-southwest of Tampa Florida
Hermine is moving northward 2 knots. The estimated minimum
central pressure is 1000 mb. The maximum sustained wind speeds
are 35 knots with gusts to 45 knots. Convective precipitation:
Numerous strong from 21N in the northern parts of the Yucatan
Peninsula to 26N in the Gulf of Mexico between 84W and 90W. It
is possible that some of the precipitation also may be reaching
parts of northwestern Cuba. Scattered to numerous strong from
27N to 29N between 82W and 84W in parts of west central Florida
and its coastal waters. Scattered moderate to isolated strong
also from 27N to 29N between 84W and 87W. Please read the latest
NHC Intermediate Public Advisory under AWIPS/WMO headers
MIATCPAT4/WTNT34 KNHC and the Forecast/Advisory under the
AWIPS/WMO headers MIATCMAT4/WTNT24 KNHC for more details.

...TROPICAL WAVES...

An Atlantic Ocean tropical wave is along 25W/26W, from 21N
southward, moving westward 15 to 20 knots. A 1012 mb low
pressure center is along the wave near 16N. Convective
precipitation: scattered moderate to strong is from 13N to 14N
between 29W and 30W. Isolated moderate to locally strong is from
03N to 10N between 20W and 40W, probably related more to the
monsoon trough.

An Atlantic Ocean tropical wave is along 42W/43W from 20N
southward, moving westward 15 to 20 knots. Convective
precipitation: nothing significant. The wave has been coinciding
with a middle level trough and its cyclonic wind flow that
covers the area that is between 35W and 40W, which has been
showing up well on satellite derived high density winds. The
wave also is on the leading edge of a well defined plume of deep
layer moisture. The tropical wave follows another mid level
trough centered near 50W/51W. Model depictions indicate the
tropical wave will dampen out during the next 24 to 36 hours
between the more developed wave to the east and the 50W/51W
trough, which is expected to move across the Leeward Islands
through late Thursday.

A surface trough is along 52W/53W, from 16N to 25N. Convective
precipitation: isolated moderate from 23N to 28N between 50W and
60W.

...ITCZ/MONSOON TROUGH...

The Monsoon Trough passes through the coastal areas of
Mauritania near 17N, to the 1012 mb low pressure center that is
along the 25W/26W tropical wave, to 08N34W and 08N40W. The ITCZ
continues from 08N40W to 10N48W and 10N51W. Convective
precipitation: Scattered strong inland, from Guyana to Venezuela
from 07N to 10N between 59W and 66W. Widely scattered moderate
to isolated strong from 08N to 13N between 47W and 61W. Isolated
moderate to locally strong is from 03N to 10N between 20W and
40W.

...DISCUSSION...

...THE GULF OF MEXICO...

The main feature is Tropical Depression Nine. Broad upper level
cyclonic wind flow covers the area from 25N northward between
Florida and Texas/Mexico. Convective precipitation: Numerous
strong from 21N in the northern parts of the Yucatan Peninsula
to 26N in the Gulf of Mexico between 84W and 90W. It is possible
that some of the precipitation also may be reaching parts of
northwestern Cuba. Scattered to numerous strong from 27N to 29N
between 82W and 84W in parts of west central Florida and its
coastal waters. Scattered moderate to isolated strong also from
27N to 29N between 84W and 87W. Surface cyclonic wind flow, that
is related to the wind flow that is moving around the tropical
depression covers the area.

...THE CARIBBEAN SEA...INCLUDING HISPANIOLA...

Upper level anticyclonic wind flow covers that part of the
Caribbean Sea that is to the northwest of the line that curves
from the border of Haiti and the Dominican Republic, toward
Colombia and northwestern Venezuela. The upper level
anticyclonic wind flow merges with broad upper level cyclonic
wind flow that covers the southern coastal waters of the
Caribbean Sea.

Comparatively drier air in subsidence is apparent in water vapor
imagery to the east of the line that runs from the Mona Passage
to northwestern coastal Venezuela. An upper level trough extends
from the coastal waters of Puerto Rico toward the Netherlands
Antilles.

24-HOUR RAINFALL TOTALS IN INCHES FOR THE PERIOD ENDING
AT31/1200 UTC...ACCORDING TO THE PAN AMERICAN TEMPERATURE AND
PRECIPITATION TABLES...MIATPTPAN/SXCA01 KNHC...are 0.71 in
Freeport in the Bahamas, 0.61 in Merida in Mexico, 0.18 in
Tegucigalpa in Honduras, 0.12 in Trinidad, and 0.11 in Nassau in
the Bahamas, 0.04 in Guadeloupe, and 0.03 in Monterrey in
Mexico.

The monsoon trough is along 09N73W in Colombia, beyond 10N84W in
Costa Rica. Convective precipitation: Earlier numerous strong
precipitation that was in northwestern Colombia has weakened and
dissipated. Widely scattered moderate to isolated strong is
from 13N southward from 76W westward.

...HISPANIOLA...

Upper level cyclonic wind flow covers Hispaniola, with an upper
level trough. The trough passes through 22N70W in the Atlantic
Ocean, across Hispaniola, to 16N71W in the Caribbean Sea.

SURFACE OBSERVATIONS...FOR PORT-AU-PRINCE IN HAITI: VFR/no
ceilings. FOR THE DOMINICAN REPUBLIC...Barahona: VFR/no
ceilings, few cumulonimbus clouds in earlier observations. Santo
Domingo/La Romana/Punta Cana: VFR/NO CEILINGS. La Romana is
reporting few cumulonimbus clouds. Santiago and Puerto Plata:
VFR/NO CEILINGS.

FOR HISPANIOLA: The GFS MODEL forecast for 250 MB shows that day
one will consist of cyclonic wind flow with the trough, becoming
SE wind flow at the end of the day as the trough moves westward.
SE wind flow will cover the area during day two, becoming
anticyclonic by the end of the day. The GFS MODEL forecast for
500 MB shows that day one will consist of SE wind flow at the
start of the day, followed by NE wind flow, and finally
easterly. E and SE wind flow will move across the area during
day two. The GFS MODEL forecast for 700 MB shows that E to SE
wind flow move across the area for the next 48 hours.

...THE REST OF THE ATLANTIC OCEAN...

An upper level trough is along 30N69W to 24N69W, to 22N70W,
across Hispaniola, to 16N71W in the Caribbean Sea. Convective
precipitation: isolated moderate to locally strong from the
Bahamas to 30N between 65W and 75W.

An upper level ridge extends from a 30N54W anticyclonic
circulation center, to 26N59W, to 22N57W and 16N58W.

An upper level trough is along 31N43W, to 25N46W, to 20N48W, and
to 16N52W.

An upper level trough extends from 38N05W in Spain, to 33N15W, to
27N19W, just to the southwest of the Canary Islands.

A surface ridge extends from a 1028 mb high pressure center that
is near 36N25W, through 32N35W and 29N39W, to 27N51W, to a 1020
mb high pressure center that is near 25N60W, to the northwestern
Bahamas.

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

$$
MT
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