000 AXNT20 KNHC 200605 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 205 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 0000 UTC surface analysis and satellite imagery through 0545 UTC. ...SPECIAL FEATURES... Please refer to the METEO-FRANCE High Seas Forecast, listed on the website: WWW.METEOFRANCE.COM/PREVISIONS-METEO-MARINE/BULLETIN/ GRANDLARGE/METAREA2. Frequent wind gusts to gale-force are forecast for the area of AGADIR. These conditions will dissipate during the next 6 hours. ...TROPICAL WAVES... A tropical wave is in the eastern Atlantic with axis extending from 12N24W to 03N24W, 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 13N56W to 06N56W, 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 08N82W, 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 14N west of 80W. ...ITCZ/MONSOON TROUGH... The Monsoon Trough enters the tropical Atlantic through Guinea near 14N17W and continues to 08N23W. The ITCZ extends west of a tropical wave from 05N27W to 02N35W to the coast of Brazil near 02S42W. 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 22N west of 90W according to both GOES IFR probabilities and surface data. In the SW Gulf, middle level diffluence support scattered showers in the central and western Bay of Campeche. Scattered heavy showers and tstms are within 60 nm off the Florida Big Bend coast supported by upper level diffluence. Water vapor and CIRA LPW show dry air across the remainder basin, which favors clear skies and fair weather. Otherwise, moderate southeasterly flow dominates basin-wide, except for locally fresh winds off the Texas coast and northeasterlies off the western Yucatan Peninsula. No major changes are expected until Sunday night when a weak cold front is forecast to move off the Texas coast. CARIBBEAN SEA... The main feature in the Caribbean is a tropical wave extending from the NW basin near 19N84W to inland Nicaragua, Costa Rica and northern Panama. Abundant moisture in the SW basin as well as upper level diffluence support heavy showers and tstms in this region. See the tropical waves section for further details. Shallow moisture across the northern basin support cloudiness with possible isolated showers, but mainly dust has been reported in the Dominican Republic as well as the Lesser Antilles. Dry air subsidence from aloft and strong deep layer wind shear support clear skies elsewhere. High pressure over the Atlantic tightens the gradient in the Caribbean to support 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... A Gale Warning is in effect for the far east Atlantic waters. Please refer to the SPECIAL FEATURES section above for details. Surface high pressure dominates the Atlantic Ocean being anchored N of the area. The exception is a surface trough that extends from 25N58W to 21N59W with scattered to isolated showers east of the trough to 50W. Abundant mid-upper level moisture persists ahead of this upper trough forecast to drift eastward. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos