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 1600 UTC.


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 morning.


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.



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. Please see the special features section for more details regarding this gale.


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.

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

$$ Latto