000 AXNT20 KNHC 152342 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 742 PM EDT Thu Jun 15 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 1800 UTC surface analysis and satellite imagery through 2330 UTC. ...TROPICAL WAVES... A strong tropical wave was added to the 1200 UTC surface map near the west coast of Africa based on visible satellite imagery and the Hovmoller Diagram. Its axis extends now from 11N16W to 04N16W. Scattered moderate convection extends from 03N-11N between 14W-21W. A tropical wave located several hundred miles south-southwest of the Cabo Verde Islands extends from 10N30W to a 1012 mb low pressure located near 06N30W to 00N30W. This wave is producing disorganized showers and thunderstorms from 03N-08N between 30W- 34W. Development, if any, of this system should be slow to occur during the next few days while the wave moves westward near 20 kt over the tropical Atlantic. The tropical wave situated along 39W on the 1200 UTC surface map was re-located farther east based on a recent ASCAT data. At this time, the axis extends from 14N37W to 07N38W, moving westward at around 10 kt. The wave remains embedded within an area of deep- layer moisture as depicted on the TPW product. The wave also coincides with an inverted trough at 700 mb. Satellite imagery show isolated convection with some cyclonic turning along the wave's axis. A tropical wave is over the eastern Caribbean and extends from western Puerto Rico to the coast of central Venezuela. Scattered showers and thunderstorms are observed across the northern half of the wave affecting the area north of 15N. The wave is very well depicted in the moisture product and 700 streamline analysis. This wave is forecast to move across Hispaniola through Friday. Another tropical wave is drifting westward across the SW Caribbean with axis from 17N82W to the coast of western Panama. Scattered moderate convection is seen on either side of the wave axis supported by a diffluent flow aloft that covers the western Caribbean mainly west of 76W. This wave will reach central America tonight, and will be absorbed by the complex low pressure system forecast to develop over the northwestern Caribbean Sea and the Yucatan Peninsula this weekend. ...MONSOON TROUGH/ITCZ... The Monsoon Trough extends from the coast of west Africa near 08N18W to 07N28W. The ITCZ extends from 10N44W to 09N60W. Three tropical waves are embedded within the Monsoon trough/ITCZ. Most of the convective activity is associated to these waves. ...DISCUSSION... GULF OF MEXICO... A surface ridge extends from the western Atlantic, across Florida into the Gulf of Mexico producing gentle to moderate E to SE winds across the area. A thermal trough, that normally develops during the evening hours over the Yucatan Peninsula and moves across the southwest Gulf during the overnight and early morning hours, extends along 90W south of 22N. Scattered to numerous showers and thunderstorms are observed along the Yucatan Peninsula near the trough. Water vapor imagery continues to reveal the presence of an upper-level low spinning over the southeast Gulf, with a trough that extends southwest across the northern Yucatan Peninsula into the eastern Bay of Campeche. Upper diffluence on the east side of the low combined with a moist and humid southeast flow at low levels will continue to support the development of scattered to numerous showers and thunderstorms over parts of the Florida Peninsula, the Florida Keys and the southeast Gulf. Abundant moisture is expected to persist over the southeast Gulf and the Yucatan Peninsula through the weekend. This weather pattern will be associated with a complex area of low pressure forecast to form over the northwestern Caribbean Sea and the Yucatan Peninsula this weekend. Conditions appear to be favorable for gradual development of this system while it moves slowly northwestward toward the southern Gulf of Mexico by early next week. CARIBBEAN SEA... Two tropical waves are moving across the Caribbean Sea. Please see the Tropical Waves section above for more details. These tropical waves will become absorbed in a broad area of low pressure forecast to form over the northwest Caribbean during the upcoming weekend. Experimental GOES-16 visible satellite imagery is already hinting the presence of a low-level circulation over eastern Honduras. This system will bring increasing winds and building seas across the central and western Caribbean during the upcoming weekend due to a tight pressure gradient between the developing low pressure and the Atlantic ridge. Plenty of moisture and very active weather is also expected with this low affecting the western and west and central Caribbean Sea as well as Central America during the weekend. Locally heavy rain could occur over parts of Cuba, the Yucatan Peninsula and Central America. At this time, scatterometer data show moderate to fresh trades across the east and central Caribbean. Gentle to moderate winds prevail over the northwest Caribbean. This wind pattern will continue through Saturday. ...HISPANIOLA... A tropical wave, currently over western Puerto Rico, will move across Hispaniola this evening through Friday supporting scattered showers and thunderstorms as it moves through. ATLANTIC OCEAN... Three tropical waves were analyzed across the basin. Please refer to the Tropical Waves section above for details. A surface trough extends from 30N55W to 26N62W. This surface feature is the reflection of an upper-level low centered near 28N57W, with a trough extending southwest towards Puerto Rico. Isolated showers are observed along this trough. Elsewhere, a broad high pressure covers the remainder of the basin anchored by a 1020 mb surface high centered near 27N68W and a 1026 mb surface high near 35N25W. Moderate to locally fresh trades are around the southern periphery of the ridge between the Windward Islands and the coast of Africa. A surge of African dust continues to spread westward in the wake of the tropical wave located along 38W as noted in the Saharan Air Layer from CIMSS. For additional information please visit http://www.hurricanes.gov/marine $$ ERA