676 AXNT20 KNHC 140608 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 208 AM EDT Sat Jul 14 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 0000 UTC surface analysis and satellite imagery through 0545 UTC. ...SPECIAL FEATURES... ...Gale Warning off the coast of Colombia in the Caribbean Sea... Gale force NE-E winds are across the south-central Caribbean from 11N to 12N between 74W and 75W with associated sea heights ranging from 12 to 13 feet. Minimal gale conditions are expected near the coast of Colombia at night through Sun night. Near gale force winds will then prevail through Wed. Please, see the High Seas Forecast, under the AWIPS/WMO headers HSFAT2/FZNT02 KNHC, for more details. ...TROPICAL WAVES... A tropical wave is in the E Atlc with extending from 05N20W to 17N18W, moving W at 10-15 kt. The wave is in a low to moderate wind shear environment and is under middle to upper level diffluent flow. However, Meteosat RGB imagery show dry air and dust engulfing the wave environment. Furthermore, the CIRA LPW imagery show intrusion of Saharan dry air to the wave environment. Due to these factors, convection has further reduced to scattered moderate from 05N-11N E of 24W. A tropical wave is in the central Atlc with axis extending from 07N47W to 19N45W, moving W at 15 kt. The wave is in a low wind shear environment. However, extensive Saharan dry air and dust intrusion to its environment hinder the development of deep convection. Isolated moderate convection is limited to the southern wave environment near the ITCZ. A tropical wave is in the E Caribbean with axis extending from 08N64W to 18N63W, moving W at 10-15 kt. CIRA LPW imagery show abundant low level moisture in its environment, however Meteosat imagery show some dry air and dust in this region, which is being reported at some Lesser Antilles Islands. Strong deep layer wind shear in the E Caribbean is partly limiting the convection of this wave to isolated moderate convection S of 17N between 63W and 67W. A tropical wave is in the central Caribbean with axis extending from 11N74W to 18N73W, moving W at 10-15 kt. GOES-16 low level water vapor imagery show very dry conditions in this region of the basin while the Dust RGB show some Saharan dust in the wave environment. These factors along with strong wind shear in the southern half of the wave are hindering convection at the time. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from 11N15W to 09N27W. The ITCZ begins near 09N27W and continues along 10N40W to 08N50W to 10N58W. Aside from the convection related to the tropical waves, scattered moderate convection is from 05N-10N between 55W-60W. ...DISCUSSION... GULF OF MEXICO... Surface ridging continues to dominate the Gulf waters being anchored by a 1020 mb high pressure center located in the SE Gulf near 25N84W. Due to a weak pressure gradient across the basin, mainly light to gentle variable flow prevail. In the eastern Bay of Campeche, a slightly tighter pressure gradient supports moderate to locally fresh NE winds off the Yucatan Peninsula. This scenario is due to a surface trough that will move westward off the Yucatan Peninsula each evening through Tue enhancing nocturnal winds. Marine guidance suggests fresh to locally strong NE-E winds and seas of 4-5 ft in association with this thermal trough. Gentle to moderate SE-S winds are expected across the western Gulf on the western periphery on the ridge. This synoptic pattern is forecast to continue to the middle of the week with seas generally under 5 ft. Otherwise, GOES-16 RGB imagery continue to show African dust in the SE Gulf, including the Yucatan Channel, which may reduce visibility. CARIBBEAN SEA... Two tropical waves will continue to move across the basin. Refer to the Tropical Waves section above for details. A gale warning continues in effect for the south-central Caribbean. Refer to the Special Features section above for more information. Dry air covers the central and western Caribbean at the lower levels as indicated by the GOES-16 low level water vapor channel. In addition, Saharan dust covers most of the Caribbean Sea, including the Greater Antilles, where partly cloudy and hazy conditions continue to be reported. High pressure will build across the region behind each passing tropical wave to freshen trade winds across the central Caribbean waters. Winds will pulse to strong to near gale force each night off the coast of Colombia through Wed, except to minimal gale force tonight, Sat night and Sun night. ATLANTIC OCEAN... An area of low pressure, associated with the remnants of Beryl, is located about 200 miles northwest of Bermuda. Although this system has become a little better organized since yesterday, upper-level winds are forecast to be only marginally conducive for additional development while the low moves north-northeastward at about 10 mph. Today, the system should reach colder waters north of the Gulf Stream, where development is unlikely. A surface trough extends from a 1014 mb low associated with the remnants of Bery N of the area to 30N69W to 27N75W. The trough is forecast to dissipate today. Scattered showers and isolated thunderstorms are along and southeast of the trough. The remainder of the Atlantic forecast area is under the influence of the Bermuda-Azores High, with a center of 1033 mb located WNW of the Azores. The ridge extends SW into the NE Caribbean and the SE Bahamas. High pressure building westward from the central Atlantic through Tue will support fresh to strong trade winds south of 23N W of 65W. Winds will pulse to strong north of Hispaniola at night this weekend. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos