000 AXNT20 KNHC 290906 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Tue Aug 29 2023 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 0700 UTC. Peak seas are currently up to 37 ft. Numerous moderate to strong convection is noted within 90 nm of the center with numerous moderate elsewhere within 180 nm in the E semicircle and 120 nm in the W semicircle. Peak seas are currently around 19-21 ft with an altimeter pass just off the coast of western Cuba just E of Cabo Corrientes, indicating seas to 23 ft which is not out of the realm of possibility given the long fetch in SW flow into the coast. Numerous moderate to strong convection is evident within 90 nm in the NE semicircle and 45 nm in the SW semicircle, with scattered moderate convection elsewhere within 25.5N84.5W to 23N81W to 14N85.5W to 14N91W. ...TROPICAL WAVES... A tropical wave is emerging off the coast of Africa near 17W/18W. Scattered moderate isolated strong convection is evident from 07N to 19N between the coast of Africa and 21W. Environmental conditions appear marginally conducive for gradual development of this system, and a tropical depression could form later in the week while the system moves west-northwestward to northwestward across the eastern tropical Atlantic. A tropical wave is in the Atlantic Ocean along 43W, from 18N southward, moving W at around 20 kt. No significant convection is evident with this tropical wave. A tropical wave is in the Atlantic Ocean approaching the Leeward Islands along 60W, from 17N southward to along the border of Guyana and Venezuela, moving W around 20 kt. Scattered moderate isolated strong convection is evident from 10N to 15N between 52W and 60W. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coastal borders of Mauritania near 19N16W to 10N30W to 07N45W. All nearby convection is described in the Tropical Waves section above. ...GULF OF MEXICO... Please read the SPECIAL FEATURES section for details about Tropical Storm Idalia whose center is N of the western tip of Cuba. Weak anticyclonic flow in the western Gulf with cyclonic flow associated with Idalia dominating the remainder of the basin. Gentle to moderate winds dominate the waters away from Idalia. Seas are 1-3 ft in the Gulf W of 91W and also N of 28N with the remainder of the basin dominated by seas generated by Idalia. For the forecast, Idalia will move to 24.9N 84.8W this afternoon, 27.8N 84.3W Wed morning, inland to 30.6N 82.9W Wed afternoon, move inland and weaken to a tropical storm near 32.7N 80.5W Thu morning, 33.8N 77.5W Thu afternoon, and 33.9N 74.4W Fri morning. Idalia will change little in intensity as it moves to 33.3N 71.5W early Sat. High pressure and improving conditions will arrive in the wake of Idalia late in the week. ...CARIBBEAN SEA... Please read the SPECIAL FEATURES section for details about Tropical Storm Idalia whose center is N of the western tip of Cuba. Refer to the Tropical Waves section above for details on a tropical wave approaching the Leeward Islands. High pressure ridging extends from E to W just N of the basin along 23N with moderate to fresh E-SE winds dominating the Caribbean away from the influence of Idalia, except light to gentle in the SW Caribbean. Seas are mainly 4-7 ft outside the influence of Idalia, except for 1-2 ft in the SW Caribbean. For the forecast, Idalia will move to 24.9N 84.8W this afternoon, then continuing N away from the NW Caribbean to 27.8N 84.3W Wed morning. Meanwhile, high pressure will build westward across the western Atlantic through Thu as Hurricane Franklin lifts north of the region. This will lead to moderate to fresh trade winds in the eastern Caribbean by tonight, then in the central Caribbean by Tue, locally strong there. ...ATLANTIC OCEAN... Please read the SPECIAL FEATURES section for details about Major Hurricane Franklin, and on Tropical Storm Idalia in the far SE Gulf of Mexico forecast to impact the waters off the SE United States. A 1016 mb low pressure (reopened invest AL92) is evident near 28N51.5W. Scattered moderate isolated strong convection is evident from 26N to 29N between 49W and 53W. Associated winds are mainly moderate to fresh, but up to strong in the deep convection per earlier ASCAT altimeter data. Recent satellite wind data also indicates that its circulation has become better defined. Environmental conditions appear favorable for additional development over the next couple of days before becoming more unfavorable by the latter part of this week as the system drifts slowly over the central subtropical Atlantic. Scattered moderate isolated strong convection is evident from 21N to 28N between 57W and 62W due to the influence of a mid to upper level feature. Away from the influence of Franklin, gentle to moderate winds dominate the open waters to the SW N Atlantic. The only exception is N of 18N and E of 30W where fresh to strong NE winds are offshore northern Africa due to a persistent tight pressure gradient over the region. Seas are 6-10 ft in that area. Seas are 3-6 ft across the remainder of the open waters. For the forecast, Franklin will move N of the area to 31.3N 70.3W this afternoon, 33.0N 68.8W Wed morning, then to 34.8N 66.3W Wed afternoon when all associated conditions begin to lift N of 31N. Meanwhile, Idalia will move to 24.9N 84.8W this afternoon, 27.8N 84.3W Wed morning, inland to 30.6N 82.9W Wed afternoon, move inland and weaken to a tropical storm near 32.7N 80.5W Thu morning, 33.8N 77.5W Thu afternoon, and 33.9N 74.4W Fri morning. Idalia will change little in intensity as it moves to 33.3N 71.5W early Sat. Expect increasing winds and building seas E of Florida beginning late tonight as Idalia moves across the Eastern Gulf of Mexico. $$ Lewitsky