000 AXNT20 KNHC 120001 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 701 PM EST Sat Mar 11 2017 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 2345 UTC. ...ITCZ/MONSOON TROUGH... The Monsoon Trough axis extends from the African coast near 07N12W to 03N20W. The Intertropical Convergence Zone extends from 03N20W to the equator at 38W to the coast of South America near 02S45W. Scattered moderate convection is from 01N-05N between 14W-26W. ...DISCUSSION... GULF OF MEXICO... Water vapor imagery indicated a zonal pattern over the Gulf characterized by a flat ridge with mean axis along 88W. Strong W to WSW flow was noted over the basin with satellite derived winds at jetstream level of 90-100 KT winds along the immediate Gulf coast. The flow was becoming more diffluent over the western Gulf in advance of a shortwave trough moving through central Texas. At the surface a stationary front extended from near Fort Myers Florida through 27.5N88W to the Louisiana-Texas border. This front was in the process of dissipating as of 2100 UTC. A weak area of low pressure of 1014 mb was noted along the Texas coast. Coastal WSR-88D data and satellite imagery indicated scattered thunderstorms were developing within 90-120 NM NE of the low with an overall increase in lightning strikes over the past half hour. E to SE return flow was increasing to 15-20 KT over the northwestern Gulf in advance of the low pressure. The area of low pressure is forecast to move NE to just south of the Louisiana coast by early Sunday then stall in the north-central Gulf into Sunday night while weakening. N to NE winds will increase in the wake of the low over the NW Gulf to 20-30 KT early Sunday then diminish slightly Sunday night. CARIBBEAN SEA... Broad anticyclonic flow prevailed over the entire Caribbean Sea with strong subsidence noted over the area S of 18N. At the surface a 1009 mb low is centered over northern Colombia near 10N73W. Retreating high pressure over the central Atlantic has relaxed the pressure gradient such that moderate to fresh trade winds were noted, generally in an area from the N coast of South America to 18N between 65W and 75W. Strongest winds were occurring along the north coast of Colombia, and in a belt from 16N to 18N south of Hispaniola. Patches of broken to overcast low clouds with embedded showers were noted over Puerto Rico, Hispaniola and eastern Cuba. Little change in overall conditions are expected over the next 24 hours. ...HISPANIOLA... As noted above, broken to overcast low and mid clouds were noted over the entire island with embedded scattered showers. The 1200 UTC Santo Domingo rawinsonde showed a fairly deep layer of moisture, up to 600 mb with precipitable water values of 1.53 inches. This is somewhat wetter than normal for March. Expect little change in these conditions over the next 24 hours. ATLANTIC OCEAN... A flat mid-to upper level trough is over the western Atlantic W of 60W. A shortwave ridge was noted E of the trough N of 25N along 45W with a downstream upper level low near 28N23W producing scattered showers. A cold front over the Atlantic extends from 31N61W to 27N75W to the east coast of Florida near Palm Beach. The front was becoming stationary west of 75W as of 2100 UTC. Scattered showers are within 60-90 NM of the front. A 1030 mb high is centered over the central Atlantic near 34N37W. A ridge axis extends SW from the high through 29N45W to 25N64W. The cold front is forecast to move east and extend from 31N54W to 26N60W to the central Bahamas by late Sunday with only widely scattered showers expected. For additional information please visit http://www.hurricanes.gov/marine $$ Cobb