AXNT20 KNHC 121628
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1228 PM EDT Thu Oct 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 1200 UTC surface analysis and satellite imagery through
Hurricane Ophelia is centered near 30.5N 35.6W at 12/1500 UTC or
about 620 nm SW of the Azores moving N-NE at 2 kt. Estimated
minimum central pressure is 978 mb. Maximum sustained wind speed
is 80 kt with gusts to 100 kt. Scattered moderate convection is
from 28N-33N between 30W-39W. See the latest Forecast/Advisory
under AWIPS/WMO headers MIATCMAT2/WTNT22 KNHC for more details.
A tropical wave extends from 08N52W to 18N49W moving W at 15-20
kt. The wave coincides with 700 mb troughing between 46W-55W and
a maximum in 850 mb relative vorticity along the wave axis near
13N. Scattered moderate and isolated strong convection is from
07N-18N between 43W-54W.
A tropical wave extends from 04N77W to 12N76W moving W at 5-10
kt. This wave coincides with very subtle 700 mb troughing and 850
mb relative vorticity over western Colombia and eastern Panama on
the southwestern periphery of a mid-level ridge anchored over the
NE Caribbean Sea. Widely scattered moderate convection is from
08N-14N between 70W-81W.
The monsoon trough extends from the African coast near 09N13W to
07N17W. The Intertropical Convergence Zone axis extends from
07N17W to 07N25W to 07N38W to 09N49W. Aside from the convection
associated with the tropical wave…isolated moderate convection
is from 05N-14N between 11W-31W.
GULF OF MEXICO…
A stationary front extends from the Florida panhandle near 30N86W
W-SW to 28N96W then S-SE to 19N94W. The northern portion of the
front remains generally precipitation-free and relatively
diffuse…however fresh to strong northerly winds are noted S of
25N W of the front with scattered showers and tstms occurring
across this area. Farther east…a surface trough is analyzed
from near the front across the Florida panhandle to 27N87W with
only a few isolated showers possible from 25N-29N between
85W-91W. Otherwise…gentle to moderate NE winds prevail across
the basin E of the front. The front is expected to become diffuse
through Thursday night and remain as a surface trough boundary
across the SW Gulf Friday.
An upper level low is centered over the Florida Straits and
portions of Cuba continuing to provide an overall lower pressure
regime and weak pressure gradient pattern across the basin. W-SW
winds aloft prevail W of 70W and are generating scattered showers
and tstms S of 14N between 70W-84W…and from 15N-20N between
80W-89W. Farther south…a tropical wave along 77W is moving
across the SW Caribbean and far western Colombia. Widely
scattered showers and tstms are occurring in the vicinity of the
wave S of 14N. Otherwise…latest scatterometer data depicts
gentle to moderate trades across the basin.
Southwestern flow aloft prevails over the island this afternoon
between an upper level low centered over the Florida Straits and
an upper level anticyclone centered near 19N64W. Cloudiness will
increase throughout the afternoon with scattered showers and
isolated tstms expected through the late evening hours.
Hurricane Ophelia is detailed above. An upper level low is
centered over the Florida Straits providing support for a surface
trough analyzed from a 1009 mb low near 23N79W NE to 26N75W to
29N71W. Scattered showers and tstms are focused primarily west of
the trough axis occurring from 23N-28N between 74W-82W. Farther
east…a weaker surface trough is noted from 20N58W to 28N55W and
is generating isolated showers and tstms from 18N-22N between
50W-57W. The remainder of the eastern Atlc outside of the
influence of Hurricane Ophelia…is under the influence of
surface ridging anchored by a 1022 mb high centered SW of the
Iberian peninsula near 37N17W.
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