000 AXNT20 KNHC 131804 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 205 PM EDT SAT AUG 13 2016 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. ...TROPICAL WAVES... Tropical wave axis is tilted from southeast to northwest along the points 10N26W to 15N28W to 21N29W. It is moving W at about 10 kt. The wave coincides with broad 700 mb troughing from 04N-21N between 22W-33W. A small upper low is embedded within the broad trough near 10N32W. Model 700 mb stream function diagnostics suggest that the wave will maintain current structure through the next 30 hours, then lose some definition into 48 hours. Widely scattered moderate convection is within 180 nm west of the wave axis from 09N-11N. Tropical wave axis extends from 07N52W to 14N52W moving W at 10-15 kt. The wave coincides with subtle 700 mb troughing between 51W-57W and a maximum in 850 mb relative vorticity in the vicinity of the wave axis near 10N as depicted in the global models. An upper trough associated with an upper low at 20N55W is helping to enhance moderate to isolated strong convection from 09N-11N within 120 nm west of the wave axis. Tropical wave axis extends from 11N89W to 20N88W moving W at 15 kt. The wave coincides with 700 mb troughing between 86W-91W, upper air sounding data from the northern Yucatan Peninsula verify the northeast to southeast wind shift along the axis. Only isolated moderate convection is noted within about 30 nm of the wave axis. ...ITCZ/MONSOON TROUGH... The Monsoon Trough axis extends from the African coast near 16N17W to 12N24W to 09N31W to 09N41W. The Intertropical Convergence Zone axis extends from 09N41W to 09N50W. Scattered moderate to isolated strong convection is seen from 05N-12N between 08W-14W. Isolated moderate convection is within 60 nm either side of axis between 29W-41W. ...DISCUSSION... GULF OF MEXICO... North-northeasterly flow aloft continues across much of the Gulf this afternoon between an upper level anticyclone centered over north-central Mexico, and an upper level low centered between Andros Island and south Florida. Mid to upper level energy continues to ride around the eastern flank of the anticyclone, and in combination with very moist southerly surface to low-level flow is resulting in scattered moderate to isolated strong convection over the northwest waters of the Gulf north of 26N between 93W-95W as well as in the western portion of the north-central Gulf n of 27N between 90W-93W. Lightning density data reveals frequent lightning occurring with some of this activity. This convection is situated to the south of a couple of 1007 mb lows analyzed over the Arklatex region. Otherwise...the remainder of the basin is under the influence of a ridge with axis extending from the Florida peninsula west-southwest to the Mexico coast near 22N98W. Generally moderate to fresh anticyclonic winds prevail with slightly stronger south to southwest winds expected across the far NW waters through Sunday. The ridge axis will slowly lift northward through the weekend with moderate to fresh E-SE winds forecast early next week. CARIBBEAN SEA... Most of the active weather in the Caribbean basin remains confined to the NW Caribbean waters associated primarily with a an upper trough that extends southwest to the northwest Caribbean from an upper low located between Andros Island and south Florida. This active weather is in the form of scattered moderate to isolated strong convection from 15N-22N between 77W- 86W. Farther east...a well-defined surface trough axis is analyzed from 13N70W to 18N66W. Maximum low-level moisture convergence and a relatively diffluent environment aloft over the eastern Caribbean is generating scattered showers and tstms within 180 nm west of the trough axis from 14N-18N. The trough is forecast to reach near 70W/71W by Sunday morning, then dissipate late Sunday or early Monday. Otherwise...trades will range from moderate to fresh breeze levels and gradually increase fresh to strong across the central waters through Monday generally between 67W-77W. ...HISPANIOLA... An upper level low is centered between Andros island and south Florida providing moist southerly flow aloft and ample middle to upper level instability for the region. As a result...isolated showers and tstms are forecast through Monday as the upper level low moves west-northwest to over south Florida. In addition...the leading edge of convection associated with the eastern Caribbean trough described above beginning to approach the far southeastern section of Hispaniola. Moisture guidance suggests that this activity will continue to hold as it passes to the south of the island, and along the southern portion of the island through Sunday evening. Gusty winds can be expected with this activity. ATLANTIC OCEAN... The upper flow pattern related to the upper level low centered between Andros Island and south Florida is pulling ample deep moisture northward from the western Caribbean Sea north to over much of the Bahama islands, and also waters between the Bahamas and south Florida. This is leading to scattered showers and thunderstorms to occur from central Cuba north to 25N and between 76W-81W. Isolated showers and tstms are elsewhere west of 70W. Farther east...a weakness within the subtropical ridging is analyzed as a pair of surface troughs...one extends from 26N72W to 32N769W, and the other one extends from 28N65W to 32N63W. Scattered moderate convection is noted within 30 nm of 29N69W, and within 30 nm of a line from 30N63W to 32N61W. The remainder of the central and eastern Atlantic is under the influence of a surface ridge anchored by a 1029 mb high centered across the Azores near 39N28W providing ample subsidence and relatively dry and stable conditions across those portions of the Atlantic basin. For additional information please visit http://www.hurricanes.gov/marine $$ Aguirre