329 AXNT20 KNHC 131046 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Wed Nov 13 2024 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 31N. 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... Central and Western Caribbean Sea Invest Area AL99: A tropical wave is near 77W from Jamaica southward across a 1008 mb low (AL99) to northern Colombia. This system is moving westward around 5 kt. Numerous heavy showers and isolated thunderstorms are occurring in the SW Caribbean from 10N to 17N between 74W and 82W. Scattered showers and isolated thunderstorms are noted in the Jamaica and Hispaniola adjacent waters. A surge of tropical moisture associated with this system will cause heavy rains over western Haiti through today, and Jamaica through Thursday. Environmental conditions appear conducive for development, and a tropical depression is likely to form within the next couple of days while the system moves slowly westward into the western Caribbean Sea. Afterward, further development is likely while the disturbance meanders over the western Caribbean Sea through the weekend. The system is forecast begin moving slowly northwestward by early next week. There is a high chance for tropical development on this system within the next 2 days. Please refer to the latest NHC Tropical Weather Outlook at www.hurricanes.gov for more details. Excessive Rainfall Risk across Southern Central America: Moist convergent southwesterly flow related to the monsoon trough will continue to cause heavy rain across Costa Rica and Panama through Saturday. The highest rainfall amounts are expected across southwestern Costa Rica and western Panama. This information is provided by the Weather Prediction Center's International Desk meteorologists. Please refer to your country's national weather bureau for more details. ...TROPICAL WAVES... Please refer to the Special Features section about a tropical wave related to AL99 at the Central Caribbean Sea. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic near the coastal border of Guinea-Bissau and Guinea near 10N15W, then runs southwestward to 09N17W. The ITCZ continues westward from 09N17W across 07N30W to 08N47W. Scattered moderate convection is seen from 02N to 11N between 10W and 41W. ...GULF OF MEXICO... A surface trough, remnants of Rafael, is just S of Louisiana along the central Gulf. The pressure gradient between this area of low pressure and a strong ridge building over the eastern United States is supporting moderate to fresh E to SE winds over the eastern half of the basin along with moderate seas to 6 ft. Light to gentle variable winds and slight seas are ongoing over the western half of the basin. Isolated showers are in the vicinity of the trough in the central Gulf. For the forecast, the surface trough, remnants of Rafael, is forecast to merge with a cold front later today. The front will then move across the NE basin through Thu night. Moderate to fresh E to SE winds over the eastern half of the basin will reach strong speeds in the NE Gulf and the Straits of Florida today as the pressure gradient tightens. Moderate to fresh northerly winds will develop over the western half of the Gulf early on Thu and spread over the eastern Gulf through Fri in the wake of the front. Looking ahead, a broad area of low pressure moving to the western Caribbean today has a high chance of becoming a tropical cyclone within the next two days. The system is forecast begin moving slowly NW by early next week and reach the SE Gulf waters by Tue with dangerous winds and seas. ...CARIBBEAN SEA... Please read the Special Features section about Invest Area AL99 and heavy rainfall. Showers and thunderstorms continue in association with a broad area of low pressure, AL99, and a tropical wave over the western Caribbean Sea. This area of low pressure is supporting moderate to fresh NE winds in the lee of Cuba and moderate winds in the central Caribbean just east of the low, including the offshore waters of Panama and Colombia. Over the eastern basin, trade winds are gentle to moderate. Seas are mainly slight basin-wide. For the forecast, environmental conditions appear conducive for development of AL99, and a tropical depression is likely to form within the next couple of days while the system moves slowly westward into the western Caribbean Sea. Afterward, further development is likely while the disturbance meanders over the western Caribbean Sea through the weekend. The system is forecast begin moving slowly NW by early next week. Regardless of development, heavy rains are expected over Jamaica and portions of Haiti during the next day or so, and over the NW and portions of the SW Caribbean through early next week. Additionally, strong to near gale force winds are expected to develop over the NW Caribbean tonight and reach gale force speed by Thu night, building rough seas across the region. Otherwise, gentle to moderate winds and slight to moderate seas will dominate the central and eastern Caribbean through the forecast period. ...ATLANTIC OCEAN... A cold front extends from 31N65W to 27N77W with fresh to strong winds ahead and behind it, N of 26N, and building seas to 9 ft. Heavy showers and tstms are ahead of the front N of 23N between 50W and 65W. Moderate for fresh NE winds are occurring across the Bahamas and the Great Bahama Bank as well as the Straits of Florida. A broad surface ridge covers the remainder central and eastern subtropical waters, which is intersected by a weakening stationary front that extends from 31N28W to 20N51W. Only isolated showers are in the vicinity of this boundary. Winds are gentle to moderate ahead and behind the front and seas are moderate to rough to 9 ft. For the forecast W of 55W, fresh to strong winds ahead and behind the cold front that extends from 31N65W to 27N77W will continue to affect the western subtropical Atlantic waters through Thu evening. Ongoing rough seas N of 29N will continue to build across the region as the front reaches from 31N55W to Puerto Rico this evening and then exit the western subtropical Atlantic waters Thu night. A second cold front is forecast to enter the NW offshore waters Thu night into Fri, affecting the offshore waters N of 26N with fresh to near gale force winds and rough seas through Sun. $$ Ramos