743 AXNT20 KNHC 061149 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 749 AM EDT Mon Aug 6 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 0600 UTC surface analysis and satellite imagery through 1145 UTC. ...SPECIAL FEATURES... Gale warning in the south-central Caribbean... A strong ridge over the E CONUS extending E to Atlc adjacent waters W of 60W will tighten the pressure gradient in the south-central Caribbean early this week as a tropical wave moves W of Hispaniola. Gale force winds are forecast for the Gulf of Venezuela Tue night and along the coast of Colombia Wed night. Please see the National Hurricane Center Atlantic High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for further details. ...TROPICAL WAVES... A tropical wave is in the central Atlc with axis extending from 07N-18N along 34W, moving W at 10-15 kt. CIRA LPW imagery show abundant shallow moisture in the wave environment. However, the wave continues to be affected by Saharan dry air and dust intrusion, which is limiting convection to isolated showers from 10N-12N between 32W-37W. A tropical wave is in the central Atlc with axis extending from 05N-16N along 46W, moving W at about 10 kt. The wave continues to be severely affected by intrusion of Saharan dry air and dust as indicated by GOES-16 RGBs, water vapor and CIRA LPW imagery at the lower levels. Shallow moisture in the vicinity of the ITCZ supports scattered moderate convection mainly S of 10N. A tropical wave is in the E Caribbean with axis S of 21N along 70W, moving W at 5-10 kt. The wave is in a very moist environment at the lower levels as indicated by CIRA LPW and GOES-16 water vapor imagery. The wave is underneath a diffluent environment between an elongated upper-level low over the central basin and S-SW flow to the E, which is supporting scattered showers N of 16N between 65W-70W. A tropical wave is in the W Caribbean with axis S of 21N along 79W, moving W at 10 kt. CIRA LPW imagery shows shallow moisture associated with the wave. Shallow moisture in the vicinity of the monsoon trough supports scattered moderate convection mainly S of 10N. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from 18N16W to 11N30W to 10N42W. The ITCZ begins W of a tropical wave near 07N48W and continues to 08N55W to 09N59W. Aside from the convection related to the tropical waves, scattered moderate convection is observed along the monsoon trough between 37W-42 and along the ITCZ. ...DISCUSSION... GULF OF MEXICO... The Bermuda high extends a ridge axis SW across the Florida Peninsula to the SW Gulf of Mexico, where a weakness in the ridge is analyzed as a surface trough from 28N95W to the Bay of Campeche near 18N92W. Scattered showers prevail along the trough. Return flow provided by the ridge continues to advect shallow moisture from the Caribbean and SW N Atlc waters into the Gulf, which is supporting scattered moderate convection across the Yucatan Channel and south-central Gulf waters between 85W-88W. Another surface trough is in the far east Gulf from the Florida Big Bend to 31N84W to 26N84W with scattered showers. Expect for convection to continue across the west Gulf through tonight. Isolated showers are forecast in the Bay of Campeche through the middle of the week associated with a thermal surface trough that will come off the Yucatan Peninsula at night. This trough will also enhance the winds to fresh off the W Yucatan Peninsula. Surface ridging is forecast to prevail through the week. CARIBBEAN SEA... GOES-16 RGBs continue to show a thin layer of Saharan dust moving across most of the basin where strong deep-layer wind shear prevails. This environment continues to suppress the development of significant convection in the region. However, shallow moisture is across the basin supporting scattered showers and tstms within 90 nm off the S coast of Cuba. The monsoon trough supports similar convection within 120 nm off southern Panama. A tropical wave is in the W Caribbean lacking convection while an upper-level low over the central basin supports scattered showers in the vicinity of a tropical wave just W of the Mona Passage. See the tropical waves section for further details. Fresh to near-gale force winds in the south-central Caribbean are forecast to increase to gale-force in the Gulf of Venezuela and off the coast of Colombia Wed and Thu, respectively. See the Special Features section for further details. ATLANTIC OCEAN... Two tropical waves are moving across the basin. Refer to the section above for details. A non-tropical, surface low pressure system centered near 31N50W is interacting with a broad upper- level low. Although thunderstorm activity has increased near and to the east of the low-level center, environmental conditions are expected to be only marginally conducive for the low to acquire subtropical or tropical characteristics while it moves little over the next day or so. By this afternoon, the low is expected to move toward the north or north-northeast and continue that motion through Tuesday. SE of this low, a surface trough extends from 31N45W to 25N53W to 26N64W supporting scattered showers and tstms N of 29N between 43W-50W. Aside from the tropical waves, the remainder of the Atlc is under the influence of surface high pressure that supports fair weather. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos/ERA