231 AXNT20 KNHC 311653 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1253 PM EDT Tue Jul 31 2018 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 1645 UTC. ...TROPICAL WAVES... A tropical wave is in the E Atlc with axis extending from 06N-17N along 22W, moving W at 10-15 kt. The wave is in a low deep layer wind shear environment, however is being severely affected by a Saharan Air Layer outbreak as depicted by GOES-16 RGBs and CIRA LPW imagery. Shallow moisture and middle level diffluence support scattered showers S of the monsoon trough from 05N-09N between 20W-28W. A tropical wave is in the central Atlc with axis extending from 07N-18N along 35W, moving W at 10-15 kt. The wave is in a low deep layer wind shear environment, however is being severely affected by Saharan Air Layer dry air and dust as depicted by GOES-16 RGBs, low-level water vapor and CIRA LPW imagery. No convection is associated with this wave at this time. A tropical wave in the central Atlc with axis extending from 07N- 17N along 51W, moving W at 15-20 kt. The wave is being supported by a middle to upper level inverted trough and is mainly in a dry air environment as depicted by GOES-16 RGBs and CIRA LPW imagery. Moderate moisture in the southern wave environment associated with the ITCZ support scattered moderate convection from 07N-12N between 50W-53W. A tropical wave is in the central Caribbean with axis extending S of 20N along 76W, moving W at 15-20 kt. The wave is mainly in a strong deep layer wind shear environment and Saharan dust is noted across the central Caribbean in GOES-16 RGBs imagery. However, CIRA LPW imagery show abundant low level moisture associated with this wave, which along diffluence aloft support scattered moderate convection between Colombia and S Panama S of 12N. An upper-level low centered E of Jamaica support isolated showers across Hispaniola and the Windward Passage. A tropical wave is moving off the Yucatan Peninsula into the E Bay of Campeche. Its axis is S of 22N along 91W, moving W at 10-15 kt. The wave is being supported by a middle-level inverted trough that along with shallow moisture support scattered showers in the SW Gulf S of 23N E of 92W. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the coast of Africa near 18N16W to 09N21W to 09N28W to 09N34W. The ITCZ begins near 09N38W and continues to 09N49W, then resumes W of a tropical wave near 10N52W and continues to the coast of Venezuela near 09N61W. Aside from the convection associated with the tropical waves, scattered showers and isolated tstms are from 08N-11N E of 17W and from 06N- 13N between 50W-62W. ...DISCUSSION... GULF OF MEXICO... The Atlc subtropical high continues to extend a ridge axis SW across the Florida Peninsula to the central Gulf, thus supporting light to gentle south-southeasterly flow. CIRA LPW imagery show very moist air at the lower levels across the basin, which is being advected from the Caribbean by the return flow. This moist environment along with diffluence aloft support scattered showers and tstms N of 23N E of 90W. In the E Bay of Campeche, a tropical wave support scattered showers. See tropical waves section for further details. Otherwise, scattered heavy showers and tstms are within 90 nm off the SE coast of Texas and SW coast of Louisiana associated with a frontal system N of the area and anchored by a 1013 mb low in NE Texas. This front is forecast to come off the coast of Texas Wed morning, stall from SW Louisiana to near Tampico, Mexico Thu morning and weakening to a surface trough late Thu night. Showers are forecast to continue in the aforementioned regions through early Fri. CARIBBEAN SEA... Abundant shallow moisture is in the NW and central Caribbean as noted in CIRA LPW imagery. This moisture along with middle to upper level diffluence is supporting scattered showers and tstms N of 18N between 79W-86W. Similar convection is in the SW basin S of 12N between 74W-84W, which is associated with the EPAC monsoon trough that connects to a 1010 mb low off the coast of Colombia near 10N76W. An upper level low off the E coast of Jamaica support isolated showers over western Dominican Republic, Haiti and the Windward Passage. GOES-16 water vapor and RGB imagery show dry air and dust across the E basin, which in part is hindering the development of convection. A new tropical wave is forecast to move across the Lesser Antilles Thu with showers for the Windward Islands. Another tropical wave will move into the E Caribbean on Sunday with showers. ATLANTIC OCEAN... Three tropical waves move across the basin...see section above. Otherwise, the Atlc subtropical high dominates the basin, thus supporting mainly fair weather conditions. Surface ridging will dominate the central and eastern Atlantic through the next couple of days providing stable and dry conditions. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos