000 AXNT20 KNHC 182352 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 744 PM EDT TUE OCT 18 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 1800 UTC surface analysis and satellite imagery through 2330 UTC. ...SPECIAL FEATURES... A non-tropical 1004 mb surface low is centered northeast of the Turks and Caicos near 24N69W with a surface trough extending from 20N74W through the low then to 27N63W. Scattered moderate convection is from 22N-26N between 64W-69W. The low is expected to acquire some tropical characteristics as upper-level winds become more conducive, and a subtropical or tropical cyclone will likely form during the next few days. There is a medium chance of tropical formation in the next 48 hours as the low moves northeast today, then toward the north and northwest later in the week. Please see the Tropical Weather Outlook under AWIPS/WMO headers MIATWOAT/ABNT20 KNHC for more details. ...TROPICAL WAVES... A tropical wave is moving across the east Atlantic with axis that extends from 15N29W to 04N31W, moving west at 5-10 kt over the past 24 hours. The wave coincides with a well defined 700 mb trough depicted by model guidance and is embedded within a surge of moisture. Scattered moderate convection is from 04N-14N between 25W-33W. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends across Africa into the east Tropical Atlantic near 11N16W to 08N26W to 05N39W. Aside from the convection related to the tropical wave, scattered moderate convection is from 05N- 08N between 37W-42W. ...DISCUSSION... ...GULF OF MEXICO... A surface ridge extends across the basin anchored by a 1018 mb high centered south of Georgia near 31N83W. With this, fair weather prevails across the basin with a light to gentle anticyclonic flow. Expect for a cold front to approach the northwest portion of the basin by Thursday. This front will continue moving south across the basin enhancing winds/convection. ...CARIBBEAN SEA... A 1010 mb surface low is centered over the west Caribbean near 16N81W. A surface trough extends from 12N82W, to the low, to 19N81W. Scattered moderate convection is observed with the low and in its vicinity mainly south of 17N between 73W-88W. A diffluent flow aloft generated east of an upper-level trough that extends across the western Atlantic is enhancing scattered to numerous showers and thunderstorms across the eastern Caribbean east of 70W. This activity is mostly affecting the western portion of Puerto Rico at this time, where flooded roads are reported and Rio Guanajibo is out of its bank and is been monitored. Scatterometer data depicts light to gentle easterly winds west of 70W while gentle to moderate southeasterly winds prevail east of 70W. Expect for a similar weather pattern to continue through the next 24 hours. ...HISPANIOLA... Isolated moderate convection is observed across the eastern portion of the island induced by a diffluent flow aloft that prevails just east of an upper-level trough that extends across the western Atlantic. These conditions will prevail through the next 24 hours, with a higher convection coverage in the afternoon hours as this upper-level flow combines with daytime heating. ...ATLANTIC OCEAN... A tropical wave is moving across the basin. Please refer to the section above for details. A surface ridge extends acros the far west Atlantic anchored by a 1018 mb high centered south of Georgia near 31N83W. To the east, the base of an upper-level trough extends west of 65W, with a diffluent flow prevailing south of 30N between 60W-65W. This flow is related to the 1004 mb surface low discussed in the Special Features section above. Scattered to numerous showers and thunderstorms are across this area and also affecting the eastern Caribbean. To the east, a stationary front was analyzed from 22N48W to 32N37W. A surface trough extends across the eastern Atlantic from 30N29W to 31N21W. Little change is expected through the next 24 hours. For additional information please visit http://www.hurricanes.gov/marine $$ ERA