000 AXNT20 KNHC 092358 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 758 PM EDT Tue May 9 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 1800 UTC surface analysis and satellite imagery through 2345 UTC. ...TROPICAL WAVES... A tropical wave is over the eastern Atlantic with axis extending from 07N25W to 02S26W, moving westward at 20 kt within the last 24 hours. CIRA LPW and water vapor imagery show the wave is embedded in a very moist environment from the surface to the upper levels. The wave is also in a favorable wind shear environment that along with upper level diffluence support numerous moderate to isolated strong convection east of the wave axis from 01N to 07N between 20W and 24W. Scattered showers are elsewhere from 03S to 07N within 300 nm west of the wave axis. A tropical wave is over the western tropical Atlantic with axis extending from 10N45W to 02S46W, moving westward at 20 kt within the last 24 hours. CIRA LPW and water vapor imagery show the wave is embedded in a mainly dry environment. The wave is also in a region of unfavorable wind shear that limits. All these factors limit the convection to isolated showers within 210 nm of the wave axis. A tropical wave is just SE of the Windward Islands with axis extending from 11N58W to inland Brazil, moving westward at 15 kt within the last 24 hours. No convection is associated with it over open waters. ...ITCZ/MONSOON TROUGH... The monsoon trough crosses the western African coast near 11N16W and extends to 05N18W. The ITCZ begins near 05N19W and continues to 03N24W, then resumes west of a tropical wave near 01N30W and continues to 01N45W. Aside from the convection associated with the tropical waves, scattered moderate convection is from 03N to 06N between 09W and 18W. ...DISCUSSION... THE GULF OF MEXICO... Fair weather and very stable conditions prevail across most of the basin being supported by middle to upper level ridging and surface high pressure being anchored by a 1020 mb high centered off the Mississippi coast near 29N88W. Water vapor and CIRA LPW imagery show dry air nearly basin-wide, which is allowing for clear skies. The exception is the SW basin where shallow moisture and middle level diffluence support broken skies and possible isolated showers in the Bay of Campeche. Moderate return flow dominates across the basin, except in the vicinity of the high center where winds are light to gentle. No significant changes expected during the next two days. CARIBBEAN SEA... A middle to upper level trough over the W Atlc extends S to a base over the NE Caribbean. East of it, middle to upper level ridging generates a diffluent wind environment that along with middle to upper level moisture support scattered showers and tstms across eastern Puerto Rico adjacent waters, the Virgin Islands and the northern Leeward Islands. Isolated showers and tstms are over Puerto Rico, the Mona Passage and the Dominican Republic being supported by a surface pre-frontal trough extending from 23N65W to western Puerto Rico. The other region of precipitation is the SW Caribbean where an active monsoon trough support scattered moderate convection from 10N to 13N between 72W and 83W. Otherwise, gentle to moderate trades are basin-wide. Showers will continue for the north-central and northeast Caribbean through Thursday as the surface trough will prevail in the region. ...HISPANIOLA... Scattered to isolated showers are across the island supported by a trough aloft and shallow moisture across the north-central Caribbean. This broad middle to upper level trough will prevail through Thursday, which will allow the continuation of showers especially during the afternoon hours. ATLANTIC OCEAN... Fair weather and clear skies are in the SW N Atlc waters west of 68W being supported by dry air subsidence from aloft. East of 68W, a weak stationary front extends from 30N62W to 24N67W to 21N70W. A pre-frontal surface trough is from 23N65W S to western Puerto Rico. Middle level troughing and upper level diffluence support scattered showers east of the front to 52W. The remainder basin is under the influence of broad surface high pressure anchored by a 1021 mb high near 29N50W which will drift SE within the next 24 hours. The stationary front is forecast to transition to a cold front tonight and move over central Atlc waters Wednesday. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos