000 AXNT20 KNHC 201031 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 631 AM EDT Sat May 20 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 1030 UTC. ...TROPICAL WAVES... A tropical wave is in the eastern Atlantic with axis extending from 12N25W to 03N27W, moving west at 10-15 kt. The wave is mainly in an unfavorable wind shear environment. Satellite imagery also show Saharan dry air and dust in the wave environment, which is supporting the lack of convection at the time. A tropical wave is in the west Atlantic with axis extending from 14N56W to 05N56W, moving west at 20 kt within the last 24 hours. CIRA LPW and SSMI TPW imagery show the wave is in a dry region. In addition, unfavorable wind shear, Saharan dry air and dust are in the wave environment supporting lack of convection at the time. A tropical wave is in the far western Caribbean with axis extending from 19N84W to 09N84W, moving west at 5-10 kt within the last 24 hours. The wave continues embedded in a very moist environment and is under a diffluent environment aloft that support scattered heavy showers and tstms in the SW Caribbean S of 13N west of 80W. ...ITCZ/MONSOON TROUGH... The Monsoon Trough enters the tropical Atlantic near 08N13W and continues to 07N23W. The ITCZ extends west of a tropical wave from 06N29W to the coast of Brazil near 02N50W. Outside of the convection associated with the tropical wave, no significant convective activity is noted at this time. ...DISCUSSION... GULF OF MEXICO... Return flow prevails across the basin, which is advecting moisture from the Caribbean into the NW Gulf to support dense fog N of 23N west of 90W, according to both GOES IFR probabilities and surface data. Showers in both the Bay of Campeche and the Florida Big Bend coastal waters have dissipated. Water vapor imagery show dry air across the remainder basin, which favors fair weather. Otherwise, moderate southeasterly flow dominates basin-wide, except for locally fresh winds off the Texas coast. No major changes are expected until Sunday night when a weak cold front is forecast to move off the Texas coast. CARIBBEAN SEA... The tropical wave formerly over the far west Caribbean has moved inland Central America. However, convection associated with the wave continue to affect the SW basin where abundant moisture as well as upper level diffluence support scattered heavy showers and tstms. See the tropical waves section for further details. Shallow moisture across the northern basin support cloudiness with possible isolated showers today, but mainly dust has been reported in the Dominican Republic as well as the Lesser Antilles. The east Pacific monsoon trough extends from Panama to northern Colombia and support scattered heavy showers and tstms S of 10N in the SW Caribbean. Dry air subsidence from aloft and strong deep layer wind shear support fair weather elsewhere. High pressure over the Atlantic tightens the gradient in the Caribbean and leads to strong to near gale force winds over the south-central Caribbean, including the Gulf of Venezuela. Fresh to strong winds are across the remainder of the central Caribbean, with fresh southeasterly winds just north of Jamaica. Fresh to strong trades will persist over the central Caribbean during the upcoming weekend. ...HISPANIOLA... Upper-level flow has become more zonal across the island with a break in the heavy rainfall from the past few days. Moisture is forecast to diminish over the upcoming weekend as the upper- level trough continues to drift eastward and the wind flow turns more to the NW. Fair weather is forecast during the day this weekend, however model guidance suggest a high chance of showers at night, both Saturday and Sunday. ...ATLANTIC OCEAN... Surface high pressure dominates the Atlantic Ocean being anchored N of the area. The exception is a surface trough that extends from 26N57W to 20N61W with scattered to isolated showers east of the trough axis to 50W. See above for tropical waves information. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos