000 AXNT20 KNHC 151045 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 645 AM EDT Thu Aug 15 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 1030 UTC. ...SPECIAL FEATURES... Potential for Heavy to Extreme Rain/Flooding from southern Mexico to Central America: Currently: scattered strong rainshowers cover the areas that are from 05N to 13N between 76W and 86W. This area encompasses Colombia near its border with Panama, across Panama, to Nicaragua, and the adjacent coastal waters in the SW Caribbean Sea and in the eastern Pacific Ocean. A large surge of moisture will continue across Colombia, Panama, Costa Rica, and southern Nicaragua during the next 24 to 36 hours. Environmental conditions remain highly favorable for heavy rains to continue to accumulate, with higher localized totals near strong topographical forcing. Earlier rainfall totals: Costa Rica measured nearly 7 inches of rainfall during the last 24 hours, with 2-4" of additional rain in the last 6 hours mostly on the north Caribbean side of the country. By Friday: the focus of the heavy rainfall will shift toward the north and northwest, to Nicaragua, El Salvador, southern Honduras/Guatemala and southern Chiapas in Mexico. Flash floods and mudslides will be the biggest hazard during this event. ...TROPICAL WAVES... An Atlantic Ocean tropical wave is along 43W/44W, from 19N southward, is moving westward 10 to 15 knots. This wave is well depicted in model guidance. Monsoon trough-related precipitation is nearby, from 10N southward. A Caribbean Sea tropical wave is along 71W/72W, from central Hispaniola southward to Lake Maracaibo in Venezuela, is moving westward 15 to 20 knots. The position of the wave was moved more to the west, based on the upper air sounding data. Dry Saharan air prevails in the wave's environment, inhibiting significant precipitation at this time. A Caribbean Sea tropical wave is along 88W, from 19N in the Yucatan Peninsula, passing through Belize, Honduras, and beyond El Salvador, into the eastern Pacific Ocean, moving westward 10 knots. Isolated moderate to locally strong rainshowers are in the Gulf of Honduras. This feature was helping to enhance the precipitation that has been near the monsoon trough, during the last 24 hours, in parts of Central America and adjacent waters S of 15N between 80W and 90W. The SPECIAL FEATURES section gives more details about a heavy rain event that is happening now and for the next day or two, from Colombia, across Central America, to southern Mexico. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coastal sections of Senegal, just to the north of its border with The Gambia, near 14N17W, to 11N24W 11N30W and 09N47W. Isolated moderate to locally strong rainshowers are within 60 nm to 120 nm on either side of the line that extends from 08N14W to 07N27W 08N48W 10N60W. Other isolated moderate rainshowers are elsewhere from 12N southward from 60W eastward. GULF OF MEXICO... Upper level anticyclonic wind flow spans the area. The GFS model shows a 700 mb trough that passes through the Florida Panhandle toward the SW corner of the Gulf of Mexico. The GFS 500 mb pattern consists of broad anticyclonic wind flow from 90W westward, and a trough from the western coast of Florida along 26N northward. A surface trough extends from the Florida Panhandle to the north central Gulf of Mexico. A cold front is inland, from central Georgia to southern Alabama and southern Mississippi. Widely scattered moderate to isolated strong rainshowers are in the Gulf of Mexico from 24N northward between Florida and 93W. The weak cold front, that is in the southeastern U.S.A., will reach the northern waters of the Gulf of Mexico later this morning. The front should stall on Friday, before moving to the north of the area on Saturday morning. Scattered moderate rainshowers and thunderstorms will continue in the northern half of the basin through Saturday. Moderate to fresh SW winds are expected in the NE waters from Thursday through Saturday, associated with the front. The wind speeds will pulse to fresh in the western Yucatan Peninsula adjacent waters each evening, associated with the diurnal surface trough. Surface high pressure will establish itself elsewhere in the region on Friday, and prevail through Monday. No tropical cyclone activity is expected during the next several days. CARIBBEAN SEA... An upper level trough extends from a cyclonic circulation center, that is just to the north of the SE Bahamas, toward northern coastal areas of Colombia. Isolated moderate rainshowers cover the areas that are from 16N northward from the NE coast of the Dominican Republic near 69W westward. The monsoon trough is along 10N73W in northern Colombia, beyond 08N81W in the western half of Panama, and into the eastern Pacific Ocean. Scattered strong rainshowers cover the areas that are from 05N to 13N between 76W and 86W. This area encompasses Colombia near its border with Panama, across Panama, to Nicaragua, and the adjacent coastal waters in the SW Caribbean Sea and in the eastern Pacific Ocean. Broken to overcast multilayered clouds and isolated moderate rainshowers are from 17N southward between 60W and 70W. The tropical wave that currently is along 72W, will move across the western Caribbean Sea on Friday and Saturday. The passage of the second wave, along with high pressure to the north of the area, will continue to support fresh to strong winds in the central and southwest Caribbean Sea through Friday night, and in the NW Caribbean Sea on Saturday and Sunday. Fresh to strong winds will resume in the south central basin on Monday evening, supported by a new tropical wave that will move across the region. No tropical cyclone activity is expected during the next several days. ATLANTIC OCEAN... An upper level trough extends from an upper level cyclonic circulation center that is between the Canary Islands and the Madeira Archipelago, to a 27N39W cyclonic circulation center, to a 22N51W cyclonic circulation center, to a third cyclonic circulation center that is just to the north of the SE Bahamas. The comparatively greatest concentration of isolated moderate to locally strong rainshowers is from 23N to 29N between 44W and 54W, and from 24N northward between 70W and 80W. Other rainshowers are possible, from 20N northward from Florida eastward, and mostly on the northern side of the trough. A surface ridge extends from a 1026 mb high pressure center that is near 34N47W, to 31N55W, to 27N70W, across the Bahamas, to 24N85W in the Gulf of Mexico, and to 25N94W a bit more to the west. A surface ridge, extending from the Bermuda High, will persist across the forecast waters through Monday. This pattern will maintain mainly gentle to moderate winds north of 22N, and moderate to fresh winds south of 22N, through most of the period. Strong winds are expected between the Turks and Caicos Islands and Hispaniola, at night, through Friday night. No tropical cyclone activity is expected for the next several days. $$ MT