Atlantic Discussion

  • NHC Atlantic Tropical Weather Discussion
    by nhcwebmaster@noaa.gov (nhcwebmaster) on August 17, 2019 at 11:13 AM

    000 AXNT20 KNHC 171113 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 713 AM EDT Sat Aug 17 2019 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 0600 UTC surface analysis and satellite imagery through 1051 UTC. ...SPECIAL FEATURES... Potential for Heavy Rainfall/Flooding, from NW Venezuela and N Colombia to Central America and southern Mexico and the Yucatan Peninsula... Expect higher localized totals near strong topographical forcing. Flash floods and mudslides are the primary hazards during this event, which has been ongoing for the last few days. The GFS model for 250 mb, for 500 mb, and for 700 mb shows one inverted trough in the SW corner of the Caribbean Sea, and a second inverted trough from El Salvador southwestward into the eastern Pacific Ocean. Currently: Scattered moderate to isolated strong rainshowers are in the SW corner of the Caribbean Sea, from 10N to 13N between 78W and 82W. Scattered moderate to isolated strong rainshowers from 10N northward between 87W and 93W, and in the coastal plains of southern Mexico within a 30 nm radius of 16N96W. Isolated to widely scattered moderate and locally strong rainshowers cover the rest of the area, including in the Caribbean Sea from 08N in Colombia northward from 70W westward. ...TROPICAL WAVES... An Atlantic Ocean tropical wave is along 26W/27W, from 17N southward, moving W 15 to 20 knots. Rainshowers are possible from 10N to 20N between Africa and 35W. A tropical wave is moving across the eastern islands of the Caribbean Sea, along 61W, from 17N southward, moving W 15 to 20 knots. This wave is well depicted in model guidance. Widely scattered moderate to isolated strong rainshowers are from 10N to 15N between 54W and 61W. A Caribbean Sea tropical wave is along 83W, from 20N southward, moving W 10 to 15 knots. A 1012 mb low pressure center is along the tropical wave near 12N. Isolated to widely scattered moderate and locally strong rainshowers cover the rest of the area, including in the Caribbean Sea from 08N in Colombia northward from 70W westward. The wave is moving through the areas of pre-existing upper level inverted troughs. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coastal border areas of Mauritania and Senegal near 16N17W, to 13N22W 08N31W and 08N36W. The ITCZ continues from 08N36W to 08N45W, and to 07N52W. Scattered moderate to isolated strong rainshowers are from 05N to 09N between 21W and 33W. Isolated moderate to locally strong rainshowers are elsewhere from 10N southward from 50W eastward. The widely scattered moderate to isolated strong rainshowers, that cover the area that is from 10N to 15N between 54W and 61W, is to the east of the 61W tropical wave. GULF OF MEXICO... The GFS model shows a 700 mb inverted trough in the NE Gulf of Mexico near 28N90W. Upper level anticyclonic wind flow is on top of the NE corner of the Gulf of Mexico. Isolated to widely scattered moderate and locally strong rainshowers cover the waters that are from 92W eastward. The current SE U.S.A. stationary front, with deep tropical moisture, continues to support the precipitation that is in the NE Gulf of Mexico. Some of this activity may contain gusty winds causing rough seas. Moderate to fresh SW winds are expected in the NE Gulf of Mexico, ahead of the front, through Sunday evening. The northern part of a tropical wave will move from the western Caribbean Sea to the far-south central Gulf of Mexico on Wednesday, accompanied by ample deep moisture. Fresh to strong winds will pulse in the western Yucatan Peninsula adjacent waters through Monday. High pressure will build westward across the rest of the area through Wednesday. CARIBBEAN SEA... The GFS model for 250 mb, for 500 mb, and for 700 mb shows one inverted trough in the SW corner of the Caribbean Sea, and a second inverted trough from El Salvador southwestward into the eastern Pacific Ocean. Scattered moderate to isolated strong rainshowers are in the SW corner of the Caribbean Sea, from 10N to 13N between 78W and 82W. Scattered moderate to isolated strong rainshowers from 10N northward between 87W and 93W, and in the coastal plains of southern Mexico within a 30 nm radius of 16N96W. Isolated to widely scattered moderate and locally strong rainshowers cover the rest of the area, including in the Caribbean Sea from 08N in Colombia northward from 70W westward. Please read the SPECIAL FEATURES section for details about the potential for heavy rain amounts and the flooding in Central America. The monsoon trough is along 11N/12N from 71W in NW coastal Venezuela beyond SW Costa Rica. A 1012 mb low pressure center is along the monsoon trough near 81W. An 83W tropical wave will move across the rest of the western Caribbean Sea through this evening. The passage of this wave, along with high pressure to the north of the area, will continue to support fresh to near gale-force trade winds in the SW Caribbean Sea tonight, and in the NW Caribbean Sea on Saturday and Sunday. Fresh to strong winds will resume in the south central Caribbean Sea on Sunday evening, being supported by the passage of a new tropical wave that currently is across the Lesser Antilles. ATLANTIC OCEAN... Upper level cyclonic wind flow covers the area that is from 20N northward from 50W westward. An upper level trough extends from a 29N52W cyclonic circulation center, to 25N62W and 25N75W, beyond NW Cuba. A surface trough is along 60W/61W from 20N to 29N. Isolated to widely scattered moderate and locally strong rainshowers are from 20N to 30N from 50W westward. A surface ridge extends from a 1024 mb high pressure center that is near 34N31W, to a 1026 mb high pressure center that is near 34N48W, to Bermuda, to 25N78W in the Bahamas, across south Florida, to 24N90W in the Gulf of Mexico. High pressure, currently dominating the forecast area, will begin to move northward, and be north of the area on Monday night. A trough, currently is about 230 nm east of 65W from 19N to 29N. The trough will track westward quickly across the eastern and central forecast waters this weekend, and into the western part of the area on Monday, before moving inland across Florida on Tuesday. The trough is expected to be accompanied by scattered rainshowers and thunderstorms. $$ MT

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