AXNT20 KNHC 221711
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
111 PM EDT Sun Oct 22 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
High pressure building behind a cold front moving off the Texas
coast tonight will tighten the pressure gradient along the
Veracruz coast of southern Mexico, and induce gale force winds
south of 21N west of 95W Monday afternoon through Tuesday
A tropical wave has an axis extending from around 21N48W to
09N49W, moving westward at around 10 kt. The wave is embedded in a
700 mb trough between 44W and 51W, and coincides with a poleward
surge in low to mid level moisture. Widely scattered moderate
convection is from 08N to 16N within 500 nm east of the wave axis.
A tropical wave has moved inland from the Caribbean and now
extends from the Yucatan Peninsula to El Salvador to the Eastern
Pacific. The wave is separating from a surface trough being left
behind over the Gulf of Honduras. This wave is clearly defined in
700 mb wind fields. Scattered moderate convection is from 16N to
22N between 85W and 90W.
The monsoon trough extends across the African coast near 10N14W
to 07N20W, where it transitions to the ITCZ that extends to 04N40W
to 08N60W. Isolated moderate convection is from 03N to 07N
between 10W and 16W, and from 07N to 13N between 50W and 63W.
GULF OF MEXICO...
Atlantic high pressure supports moderate to fresh southeast winds
over the eastern Gulf. The flow becomes more southerly and gentle
to moderate over most of the western Gulf under a weaker pressure
pattern. An outflow boundary that as of 1500 UTC emerged off the
the eastern Texas and Louisiana coasts is producing numerous
thunderstorms, with fresh to locally strong northerly winds behind
the boundary. A diffluent upper level pattern over the eastern
Gulf supports numerous showers and scattered thunderstorms south
of 29N, east of 90W. Over the next 24 hours showers and
thunderstorms will fill in over the northern gulf ahead of an
approaching cold front. The cold front will emerge off the Texas
coast tonight, and reach from the Florida Panhandle to the SW Gulf
by Monday afternoon. Gale force winds are expected off the coast
of Veracruz, Mexico by tomorrow afternoon behind this cold front.
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A tropical wave has moved inland over the Yucatan Peninsula and
central America. As of 1500 UTC, a new trough has been analyzed
over the Gulf of Honduras. The combination of the departing wave
and the trough supports convection over the northwestern
Caribbean. The eastern extent of the E Pacific monsoon trough over
Costa Rica is producing scattered moderate and isolated strong
convection S of 16N over the southwestern Caribbean. Strong
subsidence and dry air is inhibiting convection over the north
central and eastern Caribbean today. High pressure over the
western Atlantic supports fresh to strong easterly winds over much
of the central Caribbean. Over the next 24 hours convection will
continue over the western Caribbean. Winds will decrease slightly
over the basin as the high to the north weakens.
Dry air will support fair weather over the island through at
least Monday. Strong trades across the western half of the island
will weaken to under 20 kt by late Monday.
A cold front enters the area of discussion near 31N47W and extends
to 30N51W, where it transitions to a weakening stationary front to
near 27N63W. The combination of the frontal boundary and an upper
low centered near 26N64W supports scattered moderate convection
from 23N to 31N between 59W and 65W, and within 120 nm north of
the stationary front east of 59W. High pressure centered offshore
New England and another high centered east of the Azores dominate
the remainder of the Atlantic discussion waters. Aside from the
stationary portion of the front dissipating, little change is
expected over the next 24 hours.
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