[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 011808 AAA
TWDAT

Tropical Weather Discussion...AMENDED
NWS National Hurricane Center Miami FL
205 PM EDT THU SEP 01 2016

AMENDED IN ORDER TO UPDATE INFORMATION ABOUT T.S. HERMINE

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 01/1800 UTC is near 38.0N
39.2W, or about 500 nm to the west of Faiala Island in the
central part of the Azores, and about 570 nm to the west of
Lajes Air Base in the Azores. Gaston is moving east-
northeastward, 70 degrees, 21 knots. The estimated minimum
central pressure is 980 mb. The maximum sustained wind speeds
are 75 knots with gusts to 90 knots. Convective precipitation:
Scattered strong from 38N to 40N between 37W and 41W. 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 Storm Hermine at 01/1800 UTC is in the
Gulf of Mexico, near 27.8N 85.6W, or about 120 nm to the south-
southwest of Apalachicola Florida and about 165 nm to the west
of Tampa Florida The tropical storm is moving north-
northeastward, or 30 degrees, 12 knots. The estimated minimum
central pressure is 989 mb. The maximum sustained wind speeds
are 55 knots with gusts to 65 knots. Convective precipitation:
Scattered strong from 23N northward into southern sections of
Georgia and the southeastern corner of Alabama between
northeastern Florida and 88W in the Gulf of Mexico. Surface
cyclonic wind flow that is moving around Hermine covers the Gulf
of Mexico from 23N northward from 91W eastward. 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 36W/37W, from 21N
southward, moving westward 15 to 20 knots. Upper level cyclonic
wind flow accompanies an inverted trough that is near the
tropical wave, between 30W and 43W. Convective precipitation:
isolated moderate from 11N to 18N between 32W and 47W.

A surface trough is along 23N55W to 20N56W to 16N57W. Convective
precipitation: isolated moderate from 13N in the Caribbean Sea
to 28N in the Atlantic Ocean between 52W and 70W. The surface
trough is moving under the upper level ridge.

...ITCZ/MONSOON TROUGH...

The Monsoon Trough passes through the coastal areas of
Mauritania near 17N16W to 10N28W. The ITCZ is along 07N39W to
06N43W 09N56W, toward Trinidad. Convective precipitation: Widely
scattered moderate to isolated strong from 05N to 17N between
13W and 30W. Isolated moderate from 05N to 10N between 30W and
50W. Widely scattered moderate to isolated strong from 05N to
12N between 50W and 57W. Scattered strong from 09N to 14N
between 57W and 58W.

...DISCUSSION...

...THE GULF OF MEXICO...

The main feature is Tropical Storm Hermine. An upper level
trough covers the Gulf of Mexico from 90W westward. Convective
precipitation: Scattered moderate to isolated strong from 21N to
23N between 95W and the coast of Mexico.

...FOR THE OFFSHORE OIL PLATFORM SITES THAT ARE IN THE AREA
WHOSE BOUNDARIES ARE FROM 27N NORTHWARD AND FROM 88W WESTWARD...

LIFR: KVOA.

IFR: none.

MVFR: KMDJ and KMIS.

LOW LEVEL CLOUD CEILINGS AND WEATHER...FOR THE COASTAL PLAINS OF
THE U.S.A. FROM THE DEEP SOUTH OF TEXAS TO FLORIDA...

TEXAS: VFR/no ceilings. LOUISIANA: VFR/no ceilings. Mississippi:
VFR/no ceilings. Alabama: MVFR at the Mobile Downtown Airport.
Florida: light rain and MVFR in the Pensacola metropolitan area.
light drizzle and MVFR in the Panama City metropolitan area.
heavy rain in Apalachicola. light rain in Tallahassee, in Perry,
and in Cross City. rainshowers and thunder in Brooksville. rain
and MVFR in the Tampa metropolitan area, and in Sarasota, and in
Naples.

...THE CARIBBEAN SEA...

Upper level cyclonic wind flow covers Hispaniola, with an upper
level cyclonic circulation center on top of Haiti. A trough
extends from 25N73W in the Atlantic Ocean, to Haiti, to 13N74W
in the Caribbean Sea. Convective precipitation: isolated
moderate from 15N to 18N between 70W and 77W. Some of the
precipitation that is occurring between 60W and 70W also is
moving westward into the same area that is between 70W and 77W.

Upper level anticyclonic wind flow covers that part of the
Caribbean Sea that is to the west and northwest of the
Hispaniola cyclonic circulation center and trough.

Comparatively drier air in subsidence is apparent in water vapor
imagery to the east of 70W.

24-HOUR RAINFALL TOTALS IN INCHES FOR THE PERIOD ENDING AT
01/1200 UTC...ACCORDING TO THE PAN AMERICAN TEMPERATURE AND
PRECIPITATION TABLES...MIATPTPAN/SXCA01 KNHC...0.19 in Merida in
Mexico, 0.15 in Trinidad, 0.06 in Monterrey in Mexico, 0.01 in
Guadeloupe and in Curacao.

An inverted trough is in the southwestern corner of the area.
Upper level cyclonic wind flow covers the area that is from 13N
southward between northern Colombia and Nicaragua and Costa
Rica. The monsoon trough is along 10N72W near Lake Maracaibo in
northwestern Venezuela, beyond the border of Nicaragua and Costa
Rica. Convective precipitation: Isolated moderate from 12N
southward.

...HISPANIOLA...

Upper level cyclonic wind flow covers Hispaniola, with an upper
level cyclonic circulation center on top of Haiti. A trough
extends from 25N73W in the Atlantic Ocean, to Haiti, to 13N74W
in the Caribbean Sea.

SURFACE OBSERVATIONS...FOR PORT-AU-PRINCE IN HAITI: VFR/no
ceilings. FOR THE DOMINICAN REPUBLIC...Barahona: VFR/no
ceilings, and few cumulonimbus clouds. Santo Domingo/La
Romana/Punta Cana: VFR/NO CEILINGS. 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.
Anticyclonic wind flow will cover the area, gradually, during
day two, with a ridge that extends from the Atlantic Ocean,
across Hispaniola, southward into the Caribbean Sea. The GFS
MODEL forecast for 500 MB shows that day one will consist of E
to SE wind flow. Day two will consist of NE to E wind flow. The
GFS MODEL forecast for 700 MB shows that SE wind flow move
across the area for the next 48 hours.

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

A 1008 mb low pressure center is near 33N76W. A surface trough
extends from the low center to 31N79W. Convective precipitation:
Scattered moderate to strong from 29N to 34N between 71W and 75W.
Isolated moderate elsewhere from 28N northward from 68W westward.

An upper level trough extends from 25N73W in the Atlantic Ocean,
to Haiti, to 13N74W in the Caribbean Sea.

An upper level ridge extends from a 28N61W, into the east
central Caribbean Sea.

An upper level trough extends from 38N04W in Spain, to 31N13W,
across the Canary Islands, to 25N17W. An upper level cyclonic
circulation center is near 31N28W. Cyclonic wind flow that is
moving around the center covers the area from 26N to 33N between
24W and 34W.

A surface ridge extends from a 1029 mb high pressure center that
is near 36N27W, through 32N34W and 28N47W, to 25N67W, across
the Bahamas, into the Straits of Florida.

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

$$
MT
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