000 AXNT20 KNHC 231753 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 105 PM EST WED NOV 23 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 1200 UTC surface analysis and satellite imagery through 1715 UTC. ...SPECIAL FEATURES... Hurricane Otto was downgraded to Tropical Storm at 23/1200 UTC. Tropical Storm Otto is centered near 11.1N 81.0W at 23/1800 UTC or about 135 nm east-northeast of Limon, Costa Rica and about 175 nm east-southeast of Bluefields, Nicaragua moving west- northwest at 5 kt. Estimated minimum central pressure is 994 mb. Maximum sustained wind speed is 60 kt with gusts to 75 kt. Scattered moderate with embedded clusters of isolated strong convection are from 9N-13N west of 79W to inland over Costa Rica and Nicaragua. Please see latest NHC Intermediate Public Advisory under AWIPS/WMO headers MIATCPAT1/WTNT31 KNHC and the full Forecast/Advisory under AWIPS/WMO headers MIATCMAT1/WTNT21 KNHC for more details. ...ITCZ/MONSOON TROUGH... The monsoon trough extends across Africa into the east Tropical Atlantic near 8N13W to 5N20W where it transitions to the ITCZ and continues along 4N24W to east of a surface trough near 6N28W, then resumes west of the trough near 8N33W along 7N38W 10N46W to 11N61W. A surface trough embedded within the ITCZ extends from 11N29W to 6N31W with scattered showers and isolated thunderstorms from 9N-11N between 27W-31W. Clusters of scattered moderate to isolated strong convection are within 200 nm along the coast of west Africa south of 7N west of 7W, from 7N-9N between 15W-20W, and from 6N-10N between 40W-47W. Clusters of scattered moderate convection are from the ITCZ to 15N between 54W and the Windward Islands. ...DISCUSSION... ...GULF OF MEXICO... The dry and stable airmass that has dominated the the Gulf of Mexico for the last several days is beginning to be replaced by a more active scenario. An upper trough over the Central CONUS has moved into the west Gulf supporting a cold front that at 23/1500 UTC extends along the coast of Texas generating numerous showers and scattered thunderstorms west of a line from Louisiana near 30N93W to Texas near 28N96W. A surface ridge anchored over New England extends south over the Gulf east of the front and is shifting eastward ahead of the cold front. the cold front is expected to weaken from southeast Louisiana to south Texas Thursday morning. A second cold front will move into the northwest Gulf Friday overtaking the stalled front then pushing east from northeast Florida to south Texas Saturday morning. ...CARIBBEAN SEA... The primary concern this afternoon is Tropical Storm Otto. Please see Special Features above. The tail end of a stationary front that extends from the central Atlantic transitions to a surface trough over the Dominican Republic near 19N69W continuing to 16N71W. Scattered showers and possible isolated thunderstorms are inland over the north portion of Hispaniola with isolated showers dotting the northeast Caribbean north of 14N east of 72W. The low from yesterday transitioned overnight to a surface trough that now extends from 17N74W to northeast of Otto near 14N78W. Scattered to numerous showers and isolated thunderstorms are within 150 nm either side of this surface trough. Easterly trade winds are banking isolated showers in the Gulf of Honduras. Otto is forecasted to turn toward the west with an increase in forward speed tonight and Thursday where it will re-intensify to hurricane before making landfall in southeast Nicaragua. The front associated surface trough will dissipate by Thursday while the second surface trough continues westward. ...HISPANIOLA... The stationary front extends from the central Atlantic then transitions to a surface trough over the Dominican Republic near 19N69W continuing into the Caribbean and is generating scattered showers and possible isolated thunderstorms over the north portion of the island this afternoon with isolated showers possible over the remainder of the island. Lingering moisture coupled with the close proximity of the front/trough could continue to give the island showers and possible thunderstorms through Thursday with some clearing on Friday. ...ATLANTIC OCEAN... An upper ridge over the Caribbean extends a ridge over the west Atlantis south of 30N. A surface ridge anchored over New England extends over the far west Atlantic with dry, stable air north of 20N west of 55W. A broad upper trough covers the remainder of the west into the central Atlantic north of 30N supporting a cold front to 31N53W where it continues as a stationary front through 25N68W to 22N64W where it dissipates over to the Dominican Republic near 19N69W, a surface trough then continue into the Caribbean. Scattered showers and possible isolated thunderstorms are south of 20N to over Hispaniola west of the front to 73W. An upper low in the east Atlantic is centered near 22N32W supporting a surface trough that extends from 25N33W to 19N35W. Clusters of scattered showers and isolated thunderstorms are from 19N-25N between 28W-34W. An upper ridge to the east of the upper low is providing difflunce aloft to generate scattered showers from 13N-25N east of 30W to the coast of Africa including the Capo Verde Islands. A surface ridge dominates the east Atlantic north of 26N east of 45W anchored by a 1031 mb high over the Azores. The stationary front will weaken thorough tonight and dissipating by Friday. Surface ridge over the west Atlantic will prevail through Friday. A cold front will move into the northwest waters Saturday morning. For additional information please visit http://www.hurricanes.gov/marine $$ PAW