000 AXNT20 KNHC 291808 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 208 PM EDT Sat Jul 29 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 1715 UTC. ...TROPICAL WAVES... A tropical wave is in the E Atlc with axis extending from 17N26W to 07N26W, moving west at 10 kt. SSMI TPW imagery depicts the wave with a moisture area. The wave is in a region of low vertical wind shear and has Saharan dry air and dust north of 13N and west of 26W. Scattered moderate convection is from 06N-10N between 24W-28W. A tropical wave is in the central Atlc with axis extending from 18N42W to 06N42W, moving W at 10 kt. SSMI TPW imagery shows a narrow spike of moisture south of 26N between 42W-47W. The wave is in a region of low vertical wind shear, and is being severely affected by Saharan dry air and dust east and west of the wave axis. No significant convection is noted. A tropical wave is in the central Atlc with axis extending from 22N54W to 09N55W, moving west at 15 kt. The wave is in a moderate to strong vertical wind shear environment and continues to be severely affected by Saharan dry air and dust intrusion to its environment. No significant convection is noted. A tropical wave is in the central Caribbean with axis extending from 20N70W to 10N71W, moving W at 10 kt. Water vapor imagery depict dry subsident air over the wave also noticed in the CIRA LPW imagery. Besides dry air, strong vertical wind shear is in the central Caribbean, which is influencing the lack of deep convection at this time. A tropical wave is in the W Caribbean with axis extending from 21N86W to 06N86W, moving W at 15 kt. SSMI TPW imagery depicts the wave with a moisture area south of 17N. Scattered showers are inland over Central America within 180 nm of the wave axis. ...ITCZ/MONSOON TROUGH... The monsoon trough extends from 12N16W to 10N20W to 04N30W to 08N37W to 09N45W. The ITCZ extends from 09N45W to 09N60W. Besides the convection mentioned in the tropical wave section, widely scattered moderate convection is along the coast of W Africa from 06N-13N between 14W-21W. Scattered moderate to isolated strong convection is from 08N-11N between 29W-34W. Widely scattered moderate convection is from 08N-10N between 49W-53W. ...DISCUSSION... GULF OF MEXICO... A cold front is inland over the north Gulf of Mexico States producing scattered moderate convection from 29N-32N between 85W-93W. A weak surface ridge prevails across the basin with axis along 26N. Water vapor imagery and satellite derived winds indicate NW flow aloft covering most of the Gulf, with an upper level high centered over northern Texas at 35N100W. Expect the front to dip south over the northern Gulf on Sun with winds shifting to the north. Also expect 20 kt SW to W winds south of the front. CARIBBEAN SEA... Two tropical waves are moving across the basin. See above. Elsewhere, the extension of the Pacific monsoon trough is producing scattered moderate convection over the SW Caribbean, Costa Rica, Panama, and N Colombia, S of 12N. Scatterometer data shows 10-25 kt trades with strongest winds over the central Caribbean. In the upper levels, a small upper level low is centered over W Cuba near 21N80W. A small upper level high is centered over the SW Caribbean near 12N79W. Expect the SW Caribbean to continue to produce convection over the next 24 hours. ...HISPANIOLA... Presently scattered showers are over Hispaniola due to the northern extent of a tropical wave and afternoon heating. Expect more showers Sun afternoon and evening due to max heating. ATLANTIC OCEAN... Three tropical waves are moving across the basin. See above. A large 1027 mb high is centered over the central Atlantic near 32N37W producing fair weather. In the upper levels, a trough is over the W Atlantic N of 28N and W of 70W. Scattered showers and isolated thunderstorms are over this area. Upper level diffluence is also over the central Bahamas producing similar precipitation. A small upper level low is centered near 30N57W also producing similar precipitation within 300 nm of the center. For additional information please visit http://www.hurricanes.gov/marine $$ Formosa