[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 151627
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1227 PM EDT THU SEP 15 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
1600 UTC.

...SPECIAL FEATURES...
Tropical Depression Julia is centered near 31.8N 78.2W at 15/1500
UTC or about 110 nm ESE of Charleston South Carolina and about 140
nm S of Wilmington North Carolina moving E at 7 kt. Estimated
minimum central pressure is 1010 mb. Maximum sustained wind speed
is 30 kt with gusts to 40 kt. Scattered moderate and isolated
strong convection is from 30N-34N between 72W-78W. See latest NHC
forecast/advisory under AWIPS/WMO headers MIATCMAT1/WTNT21 KNHC
for more details.

Tropical Storm Ian is centered near 37.2N 50.5W at 15/1500 UTC or
about 765 nm ENE of Bermuda and about 1115 nm W of the Azores
moving NE at 21 kt. Estimated minimum central pressure is 998 mb.
Maximum sustained wind speed is 45 kt with gusts to 55 kt.
Scattered moderate convection is from 39N-43N between 49W-53W.
Widely scattered moderate convection is elsewhere from 34N-39N
between 47W-53W. See latest NHC forecast/advisory under AWIPS/WMO
headers MIATCMAT5/WTNT25 KNHC for more details.

Tropical Depression Twelve is centered near 17.7N 30.4W at
15/1500 UTC or about 380 nm WNW of the Cape Verde Islands moving
W at 11 kt. Estimated minimum central pressure is 1009 mb.
Maximum sustained wind speed is 30 kt with gusts to 40 kt.
Widely scattered moderate convection is from 12N-21N between 24W-
35W. See latest NHC forecast/advisory under AWIPS/WMO headers
MIATCMAT2/WTNT22 KNHC for more details.

...TROPICAL WAVES...
Tropical wave extends from 11N46W to 19N46W moving W at 15 kt.
The wave is likely the hybrid feature of an African easterly wave
that emerged off the coast of Africa several days ago and mid-
latitude energy dropping southward into the tropics associated
with middle to upper level low centered near 16N48W. No
significant deep convection is occurring at this time.

...ITCZ/MONSOON TROUGH...
The Monsoon Trough extends from the African coast near 08N13W to
06N19W and then from 13N38W to 10N48W. The Intertropical
Convergence Zone axis extends from 10N48W to 07N58W. Aside from
convection associated with Tropical Depression Twelve...scattered
moderate convection is from 05N-09N between 12W-18W.

...DISCUSSION...

GULF OF MEXICO...
Water vapor imagery indicates a weak middle to upper level low over
the SW Gulf centered near 23N95W that supports a surface trough
analyzed from 18N95W to 22N93W. Widely scattered showers and
isolated tstms are occurring across the SW Gulf S of 21N between
92W-96W. This is likely weakening energy that fractured northward
away from a tropical wave currently along 100W in the East Pacific
region. To the north...an upper level anticyclonic circulation is
centered over the NW Gulf waters near 28N94W with axis extending
E-SE to over the central Gulf near 26N86W. At the surface...a
broad 1011 mb low is centered near 27N95W with a surface trough
axis extending E-NE toward the Florida Big Bend region. The low
and boundary are providing focus for scattered showers and widely
scattered tstms generally N of 23N between 83W-96W. The strongest
convection is currently occurring E of the low centered in the
vicinity of 27N92W. Low-level moisture convergence within close
proximity to the trough axis and maximum middle to upper level
diffluence is likely enhancing the convection as the low drifts
toward the Texas coast. Global models indicate the low will reach
the coast by Friday morning and weaken. Thereafter...gentle to
moderate E-SE winds are anticipated through the upcoming weekend
as surface ridging re-establishes itself across the SE CONUS.

CARIBBEAN SEA...
Overall the Caribbean basin remains fairly tranquil this
afternoon. On water vapor imagery...an upper level low and
associated troughing is noted moving over the western Caribbean
centered over Jamaica near 18N78W with the trough axis extending
NE to over the SE Bahamas...and to the S-SE over the SW Caribbean
near 12N80W. Much of the western Caribbean is under the influence
of relatively dry NE flow aloft with only a few isolated showers
and tstms occurring offshore of the coast of Honduras S of 17N
between 83W-86W...and across inland portions of Belize and
Guatemala. In the SW Caribbean...scattered showers and strong
tstms are occurring S of 12N between 76W-84W due to close
proximity to the Monsoon Trough along 10N. To the east of the
trough axis...an upper level anticyclonic circulation is centered
over Puerto Rico with water vapor imagery indicating dry
conditions aloft providing for mostly clear skies N of 15N E of
75W. To the S of 15N within the southern periphery of the upper
level ridging...isolated showers and tstms are occurring from
13N-15N between 62W-71W. This moisture likely originated from the
southern extent of a surface trough analyzed across the central
Atlc from 24N53W to 13N62W. Increased precipitation is expected
across the Windward Islands through Friday as the troughing drifts
slowly westward and weakens during the weekend. Otherwise...gentle
to moderate trades prevail and are expected to persist through the
weekend with slightly stronger trades reaching occasional fresh
levels across the south-central waters S of 13N between 69W-78W.

...HISPANIOLA...
An upper level low is centered WSW of the island near 18N78W with
a trough axis extending NE to over the SE Bahamas. Water vapor
imagery indicates dry and stable conditions to the east of this
upper level low and currently skies remain clear and conditions
fair. The overall fair weather is expected to continue into Friday
and Saturday.

ATLANTIC OCEAN...
Aside from Tropical Depression Julia...the remainder of the SW
North Atlc is under the influence of weak and broad ridging
supported aloft by an upper level anticyclonic circulation
centered near 28N74W. Water vapor imagery indicates fairly dry
air aloft S of 30N W of 67W resulting in mostly clear skies and
fair conditions this afternoon. Over the central Atlc...a middle
to upper level trough axis extends from 35N57W S-SW to 25N62W that
supports a weak 1012 mb low centered near 29N60W with an equally
weak cold front extending from 32N58W through the low to 28N63W to
28N67W. A pre-frontal surface trough is analyzed to the SE of the
low center from 28N59W to 25N63W. Isolated showers are occurring N
of 24N between 55W-65W. While Tropical Storm Ian continues to race
NE north of the discussion area in the central North Atlc...a
trailing line of isolated showers is within 45 nm either side of
a line from 32N48W to 24N52W. South of this convergence line a
surface trough extends from 24N52W to near Martinique near
14N61W. Isolated showers and tstms are noted within 120 nm either
side of the boundary. Otherwise...the remainder of the eastern
Atlc is under the influence of a broad surface ridge generally N
of 25N anchored by a 1027 mb high centered SE of the Azores near
36N24W.

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

$$
HUFFMAN
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