000 AXNT20 KNHC 041219 AAA TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 819 AM EDT SUN SEP 4 2016 AMENDED FOR UPDATE TO INFORMATION ABOUT HERMINE 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 1030 UTC. ...SPECIAL FEATURES... Post-tropical cyclone Hermine is centered near 37.0N 70.0W at 04/1200 UTC, or about 260 nm to the south-southeast of the eastern tip of Long Island, and about 255 nm to the east- southeast of Ocean City, Maryland. The cyclone is moving east- northeastward 10 knots. Estimated minimum central pressure is 999 mb. Maximum sustained wind speed is 55 kt with gusts to 65 kt. Scattered moderate convection is present mainly northeast of the center from 36N to 42N between 58W and 70W. Please see the latest NHC Intermediate Public Advisory under AWIPS/WMO headers MIATCPAT4/WTNT34 KNHC and the full Forecast/Advisory under the AWIPS/WMO headers MIATCMAT4/WTNT24KNHC for more details. ...TROPICAL WAVES... A tropical wave is over the eastern Atlc extending from 10N to 21N with axis near 32W, moving west at 10 kt within the last 24 hours. A 1011 mb center of low pressure is associated with the wave and is located near 18N32W, which is expected to move NW to 20N36W within the next 24 hours. The wave is mainly within a favorable deep layer wind shear from 10N to 20N, however intrusion of Saharan dry air and dust in the wave environment is hindering deep convection north of 15N. Moist air associated with the monsoon trough and a diffluent environment aloft support scattered moderate convection from 07N to 13N between 25W and 40W. A tropical wave is over the Atlantic waters east of the Lesser Antilles extending from 09N to 19N with axis near 57W, moving west at 15-20 kt within the last 24 hours. A 1009 mb center of low pressure is associated with the wave and is located near 14N57W, which is expected to dissipate within the next 24 hours. The wave has been entering a region of unfavorable deep layer wind shear and convection around the low looks disorganized. Scattered moderate to isolated strong showers are from 12N to 19N between 52W and 65W. A tropical wave is over the western Caribbean extending from 09N to 19N with axis near 82W, moving at 15 kt within the last 24 hours. The wave is in a favorable deep layer wind shear environment that along with diffluent flow aloft support isolated heavy showers within 120 nm either side of the wave axis. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends across Africa into the east Tropical Atlantic near 13N17W to 12N30W to 10N40W to 11N49W. Aside from the convection associated with the tropical waves, little convection is observed in the vicinity of the monsoon trough. ...DISCUSSION... GULF OF MEXICO... A weak surface ridge dominates the Gulf waters east of 90W supporting light variable wind flow. A surface trough, remnants of a former frontal boundary, extends along the Florida Panhandle coastal waters to 29N89W to 27N91W with isolated showers within 20 nm of its axis. Scattered heavy showers and tstms are in the SW basin S of 24N west of 93W associated with a surface trough extending from 24N97W to 18N94W. Gentle to moderate E to SE winds are across the western basin. The surface trough generating showers in the Bay of Campeche will move inland Mexico today and surface ridging will become the main feature basin-wide, thus providing moderate return flow the next three days. CARIBBEAN SEA... A weak tropical wave is over western Caribbean waters supporting scattered heavy showers S of 20N between 80W and 85W. A second tropical wave is over Atlantic waters east of the Lesser Antilles. This system continues to produce a large area of cloudiness and showers, and is likely producing winds to near tropical storm force. Upper- level winds are forecast to become less conducive for any significant development of this disturbance while it moves westward through the Caribbean Sea this week. Regardless of development, this disturbance will produce locally heavy rainfall and gusty winds, possibly to tropical storm force, over portions of the Lesser Antilles Sunday afternoon through early Monday. Please refer to the tropical waves section for details. Fresh to strong winds are in the NE Caribbean as well as in the south-central basin. ...HISPANIOLA... Fair weather prevails across the island due to strong subsidence from aloft as indicated by water vapor imagery. Stable and fair weather is expected to continue today. On Monday, a moist airmass associated with a tropical wave will bring showers. ATLANTIC OCEAN... Post-tropical cyclone Hermine is N of forecast waters. Please refer to the special features section for details. Two tropical waves are moving across the basin. Please refer to the tropical waves section for details. A 1017 mb low formed east of Jacksonville from which a surface trough extends to 28N78W to 27N80W with isolated showers and tstms within 120 nm east of its axis N of 29N. Another surface trough is moving across the western Bahamas generating similar shower activity. The remainder basin is dominated by a weak and broad surface ridge that will prevail the next three days. For additional information please visit http://www.hurricanes.gov/marine $$ RAMOS