000 AXNT20 KNHC 211022 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 622 AM EDT Mon Aug 21 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 0600 UTC surface analysis and satellite imagery through 1015 UTC. ...SPECIAL FEATURES... A tropical wave extends along 80W S of 21N moving W at 15-20 kt. The remnant circulation of Harvey is analyzed as a 1007 mb low along the wave axis near 15N80W. Scattered moderate to isolated strong convection is from 14N-21N between 78W-86W. Gradual development of this system is still possible through Monday night while it moves west-northwestward near the coast of Honduras. It could become a tropical cyclone again before it reaches the coast of Belize or the Yucatan Peninsula early Tuesday. The remnants are expected to move into the Bay of Campeche on Wednesday, where redevelopment appears more likely due to more favorable upper- level winds. Interests in northern Nicaragua, Honduras, Belize, and the Yucatan Peninsula should monitor the progress of this system. There is a medium chance for this system to become a tropical cyclone within 48 hours. ...TROPICAL WAVES... A tropical wave off the coast of W Africa extends from 21N22W to 10N22W, moving W at 15 kt. The Hovmoller Diagram shows the westward propagation of the wave. In addition, this wave in a moist area based on SSMI TPW imagery, and has a well pronounced 700 mb trough. Scattered moderate convection is from 10N-16N between 20W-23W. A 1009 mb low is analyzed ahead of the wave near 14N27W. It is forecast to move westward in tandem with the wave over the next 24-48 hours. Saharan dust is noted W of the wave environment. A tropical wave extends from 20N52W to 10N57W moving W at 15-20 kt. The wave is well depicted on the SSMI TPW animation and 700 mb streamline analysis. The northern portion of the wave has fractured and is analyzed as a surface trough from 24N50W to 21N52W. No significant deep convection is associated with the wave itself, however, scattered moderate to isolated strong convection is associated with the surface trough from 20N-26N between 48W-53W. A tropical wave is over the Yucatan Peninsula, Guatemala, and the Eastern Pacific, from 21N90W to 10N91W, moving W at 15-20 kt. Subtle troughing is noted on 700 mb streamline analysis, and abundant moisture is observed on the SSMI TPW animation. Scattered moderate to Isolated strong convection is over the Eastern Pacific. ...ITCZ/MONSOON TROUGH... The monsoon trough extends from the African coast near 18N16W to 14N27W to 09N30W to 06N40W. Besides the convection mentioned in the tropical wave section, scattered moderate convection is from 09N-12N between 24W-29W, and from 05N-08N between 33W-38W. ...DISCUSSION... GULF OF MEXICO... Weak surface ridging is over the Gulf of Mexico with axis along 30N. 10-15 kt easterly surface flow is over the Gulf. A surface trough is over the E Gulf from 28N85W to 25N85W. Scattered showers are within 120 nm of the trough axis. In the upper levels, an upper level low is centered over the E Gulf near 26N88W enhancing the showers. Expect over the next 24 hours for surface ridging to build over the Gulf. Also expect the upper level low to remain quasi-stationary and continue to produce convection. Looking ahead, the remnant low of Harvey, currently moving across the Caribbean Sea is expected to reach Belize or the Yucatan Peninsula on Tuesday, and then move into the Bay of Campeche by the middle of the week, where redevelopment appears more likely. CARIBBEAN SEA... The primary area of concern across the Caribbean Sea is the surface low (remnants of Harvey) that is generating convection over the central Caribbean. Please, see Special Features section for more details. A tropical wave is over Central America, with axis along 90W/91W. Please, see the Tropical Waves section for details. A trough of low pressure located across the Atlantic waters, north of Hispaniola, combined with abundant tropical moisture supports the development of showers and strong thunderstorms across parts of Hispaniola, and the S Bahamas. This trough and associated moisture will continue to move WNW today. ...HISPANIOLA... Daytime heating, local sea breezes, and mountain upslope lifting will combine with available moisture to produce scattered showers and thunderstorms across the island mainly during the afternoon and evening hours. A trough of low pressure, currently located north of Hispaniola will bring increased moisture, cloudiness, and precipitation to the island. ATLANTIC OCEAN... The trough of low pressure north of Hispaniola extends from 27N71W to 19N72W. This system continues to produce disorganized showers and thunderstorms, with fresh to strong winds mainly on its northeast side based on scatterometer data. Environmental conditions are expected to be unfavorable for development of this system during the next day or two, but they could become slightly more conducive for development by midweek when the system is near the northwestern Bahamas or Florida. This feature is expected to move west-northwestward at 15-20 kt during the next few days. A pair of tropical waves are between the coast of Africa and the Lesser Antilles, and a another surface trough extends from 24N50W to 21N52W. Please, see the Tropical Waves section for details. The remainder of the Atlantic is under the influence of a ridge, with a 1023 mb high located SW of Bermuda near 32N68W. This high is forecast to remain quasi-stationary over the next 24 hours. Another 1024 high pressure is center over the central Atlantic near 32N48W. For additional information please visit http://www.hurricanes.gov/marine $$ Formosa