[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 120610
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
210 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 0000 UTC surface analysis and satellite imagery through
0500 UTC.

...SPECIAL FEATURES...

At 12/0300 UTC, the center of T.S. Irma is located near 32.4N
84.9W or about 5 NM south of Columbus, Georgia, moving NW at 13
kt. The estimated minimum central pressure is 988 mb. Maximum
sustained wind speeds are 30 kt with gusts to 40 kt. Irma is
forecast to continue weakening and cross from Georgia into Alabama
shortly, then reach the NW corner of Alabama Tuesday evening as a
Tropical Depression. Please read the latest NHC Intermediate
Public Advisory under AWIPS/WMO headers MIATCPAT1/WTNT31 KNHC and,
the Forecast/Advisory under AWIPS/WMO headers MIATCMAT1/WTNT21
KNHC for more details.

At 12/0300 UTC, the center of Hurricane Jose is near 27.1N 69.5W,
or about 350 NM NNE of Grand Turk Island, moving NE at 6 knots.
The estimated minimum central pressure is 982 mb. The maximum
sustained wind speeds are 75 kt with gusts to 90 kt. Numerous
moderate to strong convection is within 90 NM in the SE semicircle
only. Numerous moderate and scattered strong convection is noted
within 180 NM in the S and within 90 NM in the N semicircles.
Jose is forecast to 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 04N36W, moving west around 15 kt. This wave coincides
with modest troughing at 700 mb in initial model guidance. 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 13N to 20N between 35W and 40W.

A tropical wave has crossed the Windward and Leeward Islands into
the far eastern Caribbean. The wave axis extends from 20N63W to
06N63W, 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
32N42W to 15N52W. SSMI TPW satellite imagery indicates the wave
is embedded in an area of deep-layer moisture. Despite the
presence of deep-layer moisture, there is no significant
convection currently associated with this wave.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from Senegal on the west coast of
Africa near 16N16W to 11N22W to 10N28W. The trough resumes near
14N36W to low pressure 1013 mb centered near 12N45W to 11N48W. The
ITCZ continues from 11N48W to 11N52W to 13N61W. Strong upper
level divergence to the SE of an upper-level trough is generating
numerous moderate and scattered strong convection from 14N to 16N
between 40W and 45W. Scattered moderate and isolated strong
convection is occurring elsewhere from 11N to 18N between 40W and
46W.

...DISCUSSION...

GULF OF MEXICO...

The center of T.S. Irma is located over SW Georgia moving NNW
into Alabama. The large circulation of Irma is generating fresh to
strong winds over the Gulf waters N of 24N and E of 90W, where
seas still range between 8 and 11 ft. Broken to overcast low
clouds are accompanying the strong winds to the south of Irma. Dry
air wrapping around the south side of this system is limiting
shower coverage to isolated over the NE Gulf waters. Moderate to
fresh 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 22N92W to 23N97W.
South of the trough axis moderate to fresh NW winds are noted.

CARIBBEAN SEA...

A tropical wave over the far eastern Caribbean is enhancing the
trades in the vicinity of southern Windward Islands but producing
little in the way of convection at this time. The surge in the
trades should continue accompanying the wave and affecting the
southern Caribbean waters as the wave continues west. No
significant convection is observed over the basin as it is
currently situated beneath convergent upper-level flow on the
south side of ridging to the NW. 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 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 T.S. 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 an Azores
high centered near 39N26W.

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

$$
McElroy
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