000 AXNT20 KNHC 021805 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 205 PM EDT Sun Jul 2 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... ...Caribbean Gale Warning... A strong pressure gradient over the south central Caribbean supported strong to gale-force northeast to east winds from 11N to 13N between 73W and 77W. However, as of the 15Z surface analysis the gradient has weakened and the gale force winds have diminished to strong northeast to east winds. For more details, please refer to the High Seas Forecast product under AWIPS/WMO headers HSFAT2/FZNT02 KNHC. ...TROPICAL WAVES... A far eastern Atlantic tropical wave has its axis extending from 17N21W to 05N20W and it has been moving west at about 10-15 kt within the last 24 hours. The wave is entrenched in a very moist monsoonal flow that has become well established from over inland Africa to well offshore the coast of Africa, and has overtaken some of the dry air earlier noted north and west of the wave. Scattered moderate convection is within 240 nm east and 180 nm west of the wave from 08N-10N. Scattered moderate convection is to the east of the northern segment of the wave within 30 nm of 14N19W. Weak low pressure may form on the wave within the next 24 hours. Another tropical wave over the eastern Atlantic has its axis extending from 15N32W to 04N34W, moving west around 5-10 kt within the last 24 hours. Latest visible satellite imagery shows weak low pressure on the wave axis near 10N33W. This system in a moderate moist environment with patches of dry air according to CIRA LPW imagery. Satellite enhanced imagery show the intrusion from the NE of Saharan dry air and dust into this wave's environment. Shallow moisture and upper-level diffluence continue to support scattered moderate isolated strong convection from 10N- 13N between 31W-34W. Scattered moderate convection is within 30 nm of 09N33W. A rather well pronounced tropical wave per latest surface, buoy, satellite-derived winds and satellite imagery has its axis extending in a northeast to southwest fashion from near 18N65W to 14N66W to inland Venezuela near 07N67W. It is moving westward near 16 kt. The Total Precipitable Wave (TPW) animation shows that the wave is within a moderate moist environment south of 16N, while the environment north of 16N is drier and more stable. A small upper level anticyclone is observed on water vapor imagery to be located near 14N63W with the associated anticyclone consisting of generally light shear over the vicinity of the wave. Latest satellite imagery shows scattered moderate convection within 150 nm east and west of the wave from 13N-16N. Similar convection has recently developed well ahead of the wave from low- level speed convergence of the trades. This activity is within 30 nm of a line from 15N70W to 15N72.5W. Gusty winds may occur with any of the mentioned convection. The wave is forecast to move across the rest of the eastern Caribbean through early Monday, then the central Caribbean during the remainder of Monday and through Tuesday. ...ITCZ/MONSOON TROUGH... The Monsoon Trough axis extends from the west coast of Africa near 13N17W to 09N26W to 09N36W. The Intertropical Convergence Zone extends from 09N36W to 07N41W to 08N54W. Scattered moderate convection is south of the axis within 30 nm of line from 09N16W to 09N17W, and also south of the axis within 60 nm of line from 07N26W to 07N30W. Otherwise, convection observed near the Monsoon Trough and ITCZ is mainly related to tropical waves. Refer to the section above for details. ...DISCUSSION... GULF OF MEXICO... A 1021 mb surface high is centered near 28N87W, and is situated on the western extension of the Atlantic high that reaches to the Gulf. A ridge extends westward from the 1021 mb high to NE Texas. This feature continues to dominate the flow pattern throughout the basin. Gentle to moderate southeast to south flow is present west of 90W and north of 24N, while moderate northeast to east winds are south of 24N west 90W. Gentle to moderate east to southeast winds are south of 25N east of 90W, and gentle west to northwest are north of 25N east of 90W. The thermal trough that developed across the Yucatan Peninsula on Saturday evening has moved offshore, and was analyzed over the SW Gulf this morning. An area of scattered moderate to isolated strong convection developed over the SW Gulf this morning from 19N-22N between 94W-95W, and is likely to persists through the afternoon. Little change is expected in the current synoptic pattern through Tuesday. CARIBBEAN SEA... A tropical wave is moving over the eastern portion of the basin as high pressure covers the remainder of the Caribbean north of 15N west of wave and also east of the wave. Broad low pressure is present over the SW Caribbean. This in combination with the proximity of the eastern segment of the Pacific monsoon trough is resulting in clusters of scattered moderate isolated strong convection over the far SW Caribbean south of 12N and west of 80W and cover much of Costa Rica and Panama. Aside from weather conditions associated with the wave as discussed above, generally fair weather prevails elsewhere. The tropical wave is forecast to move across the across the rest of the eastern Caribbean through early Monday, then the central Caribbean during the remainder of Monday and through Tuesday. ...HISPANIOLA... Generally fair weather remains across the island at this time. Expect for diurnal-type convection to develop during this afternoon and on Monday afternoon. The atmospheric environment is forecast to become more moist and unstable on Monday as a tropical wave currently over the eastern Caribbean approaches the island. Expect increasing shower and thunderstorms during Monday and through Tuesday. Latest moisture guidance suggests that the bulk of the moisture associated with the tropical wave will pass just to the south of Hispaniola, and over mainly the southern sections of the island. ATLANTIC OCEAN... Two tropical waves were analyzed over the basin. Refer to the Tropical Waves section above for details. A large longitudinal and broad surface trough over the central Atlantic is analyzed from near 29N46W to 21N47W to near 11N48W moving steadily westward around 15 kt. The trough is surrounded by a dry and stable air mass. Only isolated weak showers and thunderstorms are noted from 26N-28N between 47W- 48W. A small upper low is just north of central Cuba near 23N76W moving westward. Scattered showers and isolated thunderstorms are within 240 nm of the low in the southeast quadrant, and elsewhere south of 26N west of 66W. The remainder of the basin remains under the influence of a broad surface ridge, anchored by a 1031 mb high centered just northeast of the Azores. This synoptic pattern will change little through Tuesday. For additional information please visit http://www.hurricanes.gov/marine $$ Aguirre