000 AXNT20 KNHC 171810 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 210 PM EDT Sat Jun 17 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 1745 UTC. ...SPECIAL FEATURES... A tropical wave is in the central Atlantic associated with a 1012 mb low centered near 06N40W. Its axis extends from 10N39W to the low to 01N39W, moving W at 20 kt within the last 24 hours. The wave is in a region of favorable wind shear and is embedded in a moderate moist environment at the lower levels according to CIRA LPW imagery. However, Saharan dry air is entering to its environment, thus limiting the convection to scattered moderate from 06N to 09N between 35W and 40W, isolated moderate showers from 04N to 08N between 42W and 45W. Current convection is being supported by upper level diffluence. This wave has a medium chance of becoming a tropical cyclone during the next two days. See the latest NHC Tropical Weather Outlook under AWISP/WMO headers MIATWOAT/ABNT20 KNHC for more details. ...TROPICAL WAVES... A tropical wave is in the E Atlc with axis extending from 10N27W to 01N28W, moving W at 20 kt within the last 24 hours. The wave is in a region of favorable wind shear, however the wave lacks deep convection at the time due to Saharan dry air intrusion to its environment. A tropical wave is in the central Atlc with axis extending from 17N47W to 08N48W, moving W at 20 kt within the last 24 hours. The wave lacks convection at the time due to unfavorable wind shear and intrusion of Saharan dry air and dust to its environment. A tropical wave is in the W Caribbean with axis extending from 20N75W to 12N77W, moving W at 10 kt within the last 24 hours. Low level moisture convergence and upper level divergence support numerous heavy showers and scattered tstms with possible gusty winds from 14N to 20N between 74W and 81W, including Jamaica and adjacent waters. ...MONSOON TROUGH/ITCZ... The Monsoon Trough extends from the coast of west Africa near 13N16W to 07N22W to 05N35W to 05N44W. The ITCZ extends from 05N44W to 06N57W. Three tropical waves are embedded within the Monsoon trough/ITCZ. See tropical waves section for information about convection. Otherwise, numerous heavy showers are in the E Atlc from 06N to 12N between 16W and 23W. Scattered moderate convection is from 01S to 07N between 22W and 35W. ...DISCUSSION... GULF OF MEXICO... A weak ridge continues to dominate the Gulf region being anchored by a 1013 mb high near 27N87W, which is forecast to dissipate within the next 24 hours. The ridge provides light to gentle variable flow E of 90W and gentle to moderate S-SE winds W of 90W. Water vapor imagery indicates the presence of a broad upper-level low covering most of the basin along with very dry air, which is supporting clear skies and fair weather across most of the basin. However, weather conditions will change Sunday associated with a broad area of low pressure forecast to form over the northwestern Caribbean Sea and the Yucatan Peninsula later today or early tomorrow. Conditions appear to be favorable for gradual development of this system while it moves slowly northwestward into the southern Gulf of Mexico early next week. Latest Tropical Weather Outlook gives this low pressure a high chance of development through 5 days. CARIBBEAN SEA... Convection is on the increase across the western Caribbean. Satellite imagery show clusters of heavy showers and tstms with possible gusty winds associated with a surface trough from 21N85W to inland Honduras near 14N86W and a tropical wave moving across Jamaica. See the tropical waves section above for details. A diffluent pattern aloft, associated with the above mentioned upper-level low over the Gulf of Mexico, is helping to induce all this convective activity. A broad area of low pressure has formed in this area and continues to organize. There is a high chance of tropical cyclone development associated with this area of low pressuere over the southern or central Gulf of Mexico by early next week. This system will bring increasing winds and building seas across the central and western Caribbean this weekend due to a tight pressure gradient between the low pressure area and the Atlantic ridge. Aside from fresh to strong winds with gusty winds N of 13N between 73W and 75W, mainly gentle to moderate winds are elsewhere. Plenty of moisture and very active weather is also expected with this low, likely affecting the western and central Caribbean Sea, Central America, and most of Cuba during this weekend. Locally heavy rain and gusty winds could occur over parts of Cuba, the Yucatan Peninsula and Central America. ...HISPANIOLA... Scattered showers are across the island being supported by the broad area of diffluence in the NW Caribbean and the area of low pressure mentioned above. Showers are forecast to continue through early Sunday. ATLANTIC OCEAN... Three tropical waves are moving westward between the coast of Africa and the Lesser Antilles. Please refer to the Tropical Waves section above for details. Otherwise, broad high pressure covers the Atlantic from the Azores to the Florida Peninsula, with a 1026 mb high pressure near 31N34W. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos