[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 121048
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
648 AM EDT Tue Sep 12 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 0600 UTC surface analysis and satellite imagery through
1100 UTC.

...SPECIAL FEATURES...

At 12/0900 UTC, the Weather Prediction Center in College Park
Maryland began issuing advisories on what is now Post Tropical
Cyclone Irma. The center of Post Tropical Cyclone Irma is located
near 33.0N 85.2W or about 90 nm ESE of Birmingham, Alabama, moving
NNW at 9 kt. The estimated minimum central pressure is 998 mb.
Maximum sustained wind speeds are 15 kt with gusts to 20 kt. Irma
is forecast to continue weakening and cross from Georgia into
Alabama shortly, then reach the NW corner of Alabama Tuesday
evening. Please refer to Public Advisories issued by the Weather
Prediction Center under AWIPS/WMO headers MIATCPAT1/WTNT31 KWNH
for more details.

At 12/0900 UTC, the center of Hurricane Jose is near 27.5N 69.0W,
or about 380 nm NNE of Grand Turk Island, moving E at 6 knots.
The estimated minimum central pressure is 987 mb. The maximum
sustained wind speeds are 65 kt with gusts to 80 kt. Numerous
moderate and scattered strong convection is noted within 180 NM in
the SE and within 120 nm in the NW semicircles. Jose is forecast
to slowly make an anti-cyclonic loop northeast of the Bahamas
during the next several days. Please read the latest NHC
Forecast/Advisory under AWIPS/WMO headers MIATCMAT2/WTNT22 KNHC
for more details.

...TROPICAL WAVES...

A tropical wave over the E Atlantic has an axis extending from
18N35W to 05N39W, moving west around 15 kt. This wave is becoming
displaced from troughing in initial model 700 mb wind fields due
to interaction with a sharp mid to upper-level trough stretching
from 32N41W to 14N50W. SSMI TPW satellite imagery indicates the
wave is embedded in an area of deep-layer moisture. Scattered
moderate and isolated strong convection is present from 19N to
22N between 35W and 38W.

A tropical wave has crossed the Windward and Leeward Islands into
the far eastern Caribbean. The wave axis extends from 19N64W to
06N64W, moving west around 15 kt. This wave coincides with modest
troughing in initial model 700 mb wind fields. SSMI TPW satellite
imagery indicates the wave is embedded in an area of deep-layer
moisture. Isolated showers and thunderstorms have developed over
the SE Caribbean from 11N to 13N between 60W and 69W during the
past 6 hours.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from Senegal on the west coast of
Africa near 15N17W to 12N24W to 16N35W to low pressure 1011 mb
centered near 13N47W to 12N53W. The ITCZ continues from 12N53W to
12N61W. Strong upper level divergence to the SE of an upper-
level trough is generating scattered moderate and isolated strong
convection from 14N to 19N between 39W and 48W. Scattered
moderate and isolated strong convection is occurring from 12N to
14N between 48W and 56W.

...DISCUSSION...

GULF OF MEXICO...

Post Tropical Cyclone Irma is located on the Georgia/Alabama State
Line. Irma should continue a general northwestward motion and
approach the Tennessee Valley this afternoon. The large
circulation of Irma is generating moderate to fresh winds over
the Gulf waters N of 28N and E of 90W, where seas are subsiding
but still range between 5 and 8 ft. Dry air wrapping around the
south side of this system has cleared out cloud cover over the NE
Gulf. Shower coverage over the NE Gulf waters is virtually nil.
Moderate northerly winds generally prevail over the western half
of the basin as a surface ridge builds across the area. A surface
trough over the Bay of Campeche extends from 21N90W to 22N96W.
South of the trough axis moderate to fresh NW winds are noted.
Cloudiness and isolated showers are seen in the vicinity of the
trough from 20N to 23N between 92W and 95W.

CARIBBEAN SEA...

A tropical wave over the far eastern Caribbean is enhancing the
trades in the vicinity of southern Windward Islands but is only
producing isolated showers and thunderstorms from 11N to 13N from
60W to 69W. A surge in the trades should continue accompanying the
wave and affect the southern Caribbean waters as the wave
continues west. Scatterometer data depicts light to moderate
trades across most of the area as the sub-tropical high to the
north is weakened by Jose. West of 80W moderate to fresh southerly
winds prevail to the south of Irma.

...HISPANIOLA...

The relatively dry weather regime over the Caribbean extends over
the island. Shower coverage should be limited to the higher
terrain during daytime heating, when isolated thunderstorms can be
expected.

ATLANTIC OCEAN...

Please see the Special Features section above for information
concerning Post Tropical Cyclone Irma and Hurricane Jose. Also,
see the tropical waves section for information concerning the
tropical waves over the basin. Aside for these areas, the
remainder of the basin remains under the influence of ridging
extending SW from a 1025 mb Azores high centered near 39N26W.

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

$$
McElroy
This weather bulletin was brought to you by:
www.nashvilleweather.net