[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 131830 CCA
TWDAT

AXNT20 KNHC DDHHMM
TWDAT

Tropical Weather Discussion...corrected
NWS National Hurricane Center Miami FL
205 PM EDT SAT AUG 13 2016

corrected Atlantic ocean section for trough position

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
1745 UTC.

...TROPICAL WAVES...
Tropical wave axis is tilted from southeast to northwest along
the points 10N26W to 15N28W to 21N29W. It is moving W at 10-15 kt.
The wave coincides with broad 700 mb troughing from 04N-21N
between 22W-33W. A small upper low is embedded within the broad
trough near 10N32W. Model 700 mb stream function diagnostics
suggest that the wave will maintain current structure through
the next 30 hours, then lose some definition into 48 hours.
Widely scattered moderate convection is within 180 nm west of
the wave axis from 09N-11N.

Tropical wave axis extends from 07N52W to 14N52W moving W at 10-15 kt.
The wave coincides with subtle 700 mb troughing between 51W-57W
and a maximum in 850 mb relative vorticity in the vicinity of
the wave axis near 10N as depicted in the global models. An
upper trough associated with an upper low at 20N55W is helping
to enhance moderate to isolated strong convection from 09N-11N
within 120 nm west of the wave axis.

Tropical wave axis extends from 11N89W to 20N88W moving W at 15 kt.
The wave coincides with 700 mb troughing between 86W-91W, upper
air sounding data from the northern Yucatan Peninsula verify the
northeast to southeast wind shift along the axis. Only isolated
moderate convection is noted within about 30 nm of the wave
axis.

...ITCZ/MONSOON TROUGH...
The Monsoon Trough axis extends from the African coast near 16N17W to
12N24W to 09N31W to 09N41W. The Intertropical Convergence Zone axis
extends from 09N41W to 09N50W. Scattered moderate to isolated
strong convection is seen from 05N-12N between 08W-14W. Isolated
moderate convection is within 60 nm either side of axis between
29W-41W.

...DISCUSSION...

GULF OF MEXICO...
North-northeasterly flow aloft continues across much of the Gulf
this afternoon between an upper level anticyclone centered over
north-central Mexico, and an upper level low centered between Andros
Island and south Florida. Mid to upper level energy continues to
ride around the eastern flank of the anticyclone, and in combination
with very moist southerly surface to low-level flow is resulting
in scattered moderate to isolated strong convection over the northwest
waters of the Gulf north of 26N between 93W-95W as well as in the western
portion of the north-central Gulf n of 27N between 90W-93W. Lightning
density data reveals frequent lightning occurring with some of this activity.
This convection is situated to the south of a couple of 1007 mb lows
analyzed over the Arklatex region. Otherwise...the remainder of
the basin is under the influence of a ridge with axis extending
from the Florida peninsula west-southwest to the Mexico coast
near 22N98W. Generally moderate to fresh anticyclonic winds
prevail with slightly stronger south to southwest winds expected
across the far NW waters through Sunday. The ridge axis will
slowly lift northward through the weekend with moderate to fresh
E-SE winds forecast early next week.

CARIBBEAN SEA...
Most of the active weather in the Caribbean basin remains
confined to the NW Caribbean waters associated primarily with a
an upper trough that extends southwest to the northwest
Caribbean from an upper low located between Andros Island and
south Florida. This active weather is in the form of scattered
moderate to isolated strong convection from 15N-22N between 77W-
86W. Farther east...a well-defined surface trough axis is
analyzed from 13N70W to 18N66W. Maximum low-level moisture
convergence and a relatively diffluent environment aloft over
the eastern Caribbean is generating scattered showers and tstms
within 180 nm west of the trough axis from 14N-18N. The trough
is forecast to reach near 70W/71W by Sunday morning, then
dissipate late Sunday or early Monday. Otherwise...trades will
range from moderate to fresh breeze levels and gradually
increase fresh to strong across the central waters through
Monday generally between 67W-77W.

...HISPANIOLA...
An upper level low is centered between Andros island and south Florida
providing moist southerly flow aloft and ample middle to upper level
instability for the region. As a result...isolated showers and tstms
are forecast through Monday as the upper level low moves west-northwest
to over south Florida. In addition...the leading edge of convection
associated with the eastern Caribbean trough described above beginning
to approach the far southeastern section of Hispaniola. Moisture guidance
suggests that this activity will continue to hold as it passes
to the south of the island, and along the southern portion of
the island through Sunday evening. Gusty winds can be expected
with this activity.

ATLANTIC OCEAN...corrected
The upper flow pattern related to the upper level low centered between
Andros Island and south Florida is pulling ample deep moisture northward
from the western Caribbean Sea north to over much of the Bahama islands,
and also waters between the Bahamas and south Florida. This is
leading to scattered showers and thunderstorms to occur from
central Cuba north to 25N and between 76W-81W. Isolated showers
and tstms are elsewhere west of 70W. Farther east...a weakness
within the subtropical ridging is analyzed as a pair of surface
troughs...one extends from 26N72W to 32N69W, and the other one
extends from 28N65W to 32N63W. Scattered moderate convection is
noted within 30 nm of 29N69W, and within 30 nm of a line from
30N63W to 32N61W. The remainder of the central and eastern
Atlantic is under the influence of a surface ridge anchored by a
1029 mb high centered across the Azores near 39N28W providing
ample subsidence and relatively dry and stable conditions across
those portions of the Atlantic basin.

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

$$
Aguirre
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