000 AXNT20 KNHC 170918 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Thu Jun 17 2021 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 0800 UTC. ...SPECIAL FEATURES... A broad low pressure area located over the eastern portion of the Bay of Campeche is producing widespread cloudiness and disorganized showers and a few thunderstorms. This system will move little today, and little if any development is expected during that time due to interaction with land and unfavorable upper-level winds. However, the low should begin to move northward by this afternoon, and a tropical or subtropical depression is likely to form by late tonight or on Fri when the low moves across the western Gulf of Mexico. Regardless of development, heavy rainfall will continue over portions of Central America and southern Mexico during the next few days. Heavy rains should also begin to affect portions of the northern Gulf Coast on Fri. Please consult products from your local meteorological service for more information. This area has a high chance of tropical cyclone formation in the next 48 hrs. Please refer to the latest Tropical Weather Outlook issued by the NWS National Hurricane Center at www.hurricanes.gov for more details on this area. ...TROPICAL WAVES... An Atlantic tropical wave axis is analyzed near 39W/40W from 19N southward, moving W at around 20 kt. Scattered moderate convection is noted from 10N to 13N between 34W and 41W. An Atlantic tropical wave is approaching the eastern Caribbean Islands and is analyzed near 49W/60W from 20N southward, moving W at around 20 kt. Scattered moderate and isolated strong convection is noted from 12N to 16N between 56W and 62W. Intense lightning and squalls with very gusty winds have been reported with this convection at Barbados. Scattered moderate convection is also noted south of 10N to the north coast of South America between 55W and 60W. A Caribbean Sea tropical wave axis is analyzed near 80W/81W from 18N southward across western Panama, moving W at 10 to 15 kt. No significant convection is directly related to the tropical wave. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coast of Africa near 11N15W to 07N21W. Segments of the ITCZ are analyzed from 07N21W to 05N28W to 07N35W, then resumes near 07N41W to 04N47W to the coast of French Guiana at 05.5N53W. Scattered moderate and isolated strong convection is noted within 270 nm south of the ITCZ and monsoon trough between 19W and 30W, from 07N to 10N between 22W and 25W, and within 120 nm north of the ITCZ between 43W and 53W. GULF OF MEXICO... Refer to the Special Features section above for details on a broad low pressure area over the Bay of Campeche. A surface trough is analyzed from 26N90W to the 1008 mb broad area of low pressure described above near 20.5N92.5W. Aided by upper-level divergent flow, scattered moderate and isolated strong convection is occurring across the waters south of 26N and east of 91W, including across the Yucatan Channel and western Straits of Florida where frequent lightning is noted. A band of scattered thunderstorms has developed within 60 nm of the coast of Mexico west of 94W induced by the counter-clockwise flow around the broad area of low pressure up against the eastern slopes of Mexico. A stationary front is analyzed from along the Georgia/Florida border to across the northern Gulf along 29N/30N to southeast Louisiana. Scattered showers and isolated thunderstorms are near this front. A broad ridge axis is located between the stationary from and broad area of low pressure, roughly along 27N/28N. Gentle to moderate anticyclonic winds are noted north of 26N, moderate to fresh E-SE winds are noted south of 26N and east of the trough, with moderate to fresh winds elsewhere. Seas are mainly in the 2-4 ft range, except 4-5 ft in the central Gulf near the trough, and also in the western Bay of Campeche. For the forecast, high pressure is forecast to build in across the basin in the wake of the low pressure area described above later in the upcoming weekend into early next week. CARIBBEAN SEA... A tropical wave is moving across the western Caribbean while another wave is approaching the Lesser Antilles. Refer to the Tropical Waves section above for details. The eastern Pacific Ocean monsoon trough extends across Panama to NW Colombia near 10N75W. Scattered moderate and isolated strong convection is noted from 07N to 10N between 75W and 81W. Scattered showers and thunderstorms are noted in the NW Caribbean including across the Yucatan Peninsula, Yucatan Channel, and western Cuba around a broad area of low pressure northwest of the basin in the SW Gulf of Mexico. Scattered showers and isolated thunderstorms are occurring in the eastern Caribbean ahead of an approaching tropical wave. Fresh to strong NE-E winds were captured by overnight scatterometer data in the S central Caribbean. Fresh to strong E-SE winds are pulsing in the NW Caribbean northeast of the Gulf of Honduras. Mainly moderate to fresh trades prevail elsewhere, except gentle to moderate in the SW Caribbean south of 11N. Seas of 2 to 4 ft are in the SW Caribbean south of 11N, with mainly 4-7 ft seas elsewhere, locally to 8 ft in the S central Caribbean. For the forecast, a ridge of high pressure north of the basin combined with lower pressure over Central America and Colombia will support pulsing fresh to strong trades over the S central Caribbean and Gulf of Honduras through the upcoming weekend and into early next week. Moderate to fresh trades will prevail elsewhere, except light to gentle south of 11N. ATLANTIC OCEAN... A pair of tropical waves are moving westward between the west coast of Africa and the Lesser Antilles. Refer to the Tropical Waves section above for details. A diffluent flow aloft continues to support scattered moderate convection over the Florida Peninsula and western Atlantic mainly west of 75W. A stationary front extends from 1012 mb low pressure north of the area near 32N76W to along the Georgia/Florida border. Scattered showers and thunderstorms are near the front including across the waters north of 29N and west of 70W. To the east, a surface ridge dominates the entire Atlantic forecast area anchored by the Bermuda-Azores High located north of the area. Fresh to locally strong SW winds are occurring within 180 nm southeast of the stationary front. Moderate to fresh trades dominate south of 22N, and north of 22N east of 50W. Gentle to moderate trades prevail elsewhere, except from 18N to 24N between the west coast of Africa and 25W where fresh to locally strong N-NE winds persist due to a locally tight pressure gradient. Seas are 7 to 10 ft in this area. Seas of 5 to 8 ft prevail across the waters elsewhere south of 22N, with mainly 4 to 7 ft seas across the remainder of the tropical Atlantic waters. For the forecast west of 65W, a ridge of high pressure across the area will retreat eastward today enabling a trough to move through the northern forecast waters through Fri. High pressure will then return to the area this weekend into early next week. $$ Lewitsky