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| #1108917 (Received by flhurricane at: 4:42 PM 25.Sep.2022) TCDAT3 Tropical Storm Gaston Discussion Number 22 NWS National Hurricane Center Miami FL AL082022 900 PM GMT Sun Sep 25 2022 Gaston this evening consists of a well-defined, low-level swirl absent of any deep convection. All of the earlier activity dissipated shortly after 1200 UTC and if deep, organized convection does not quickly return near the center, Gaston could soon become post-tropical. Both subjective and objective Dvorak estimates have been decreasing, though there were enough derived motion winds between 925-850 mb (around 50 kt) to lower the intensity down to just 40 kt for this advisory. Gaston has continued to turn leftward, with the latest estimated motion now south of due west at 260/9 kt. A deep-layer southwest-to-northeast oriented ridge is becoming established northwest of Gaston, which should maintain the system on a west-southwest heading for the next several days until the closed-circulation opens up into a trough. The guidance took another southward shift this cycle, and the NHC track forecast follows the guidance in bending the track a bit more southward, following the reliable consensus aids. Gaston has lost its earlier baroclinic support that maintained instability aiding last night`s convective resurgence. The global and regional hurricane models are in good agreement that Gaston will fail to produce any additional convective bursts in an environment of strong northerly vertical wind shear, 24-25 C SSTs, and significant synoptic forcing for descent on the upwind side of a upper-level trough. Gaston is now forecast to become a post-tropical cyclone in 12 hours, but this could occur as quickly as tonight if convection does not return soon. The post-tropical low should gradually fill thereafter, opening up into a trough by 60 hours. FORECAST POSITIONS AND MAX WINDS INIT 25/2100Z 39.1N 37.5W 40 KT 45 MPH 12H 26/0600Z 38.6N 39.0W 35 KT 40 MPH...POST-TROPICAL 24H 26/1800Z 38.0N 40.9W 30 KT 35 MPH...POST-TROP/REMNT LOW 36H 27/0600Z 37.4N 43.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 27/1800Z 36.9N 46.1W 25 KT 30 MPH...POST-TROP/REMNT LOW 60H 28/0600Z...DISSIPATED $$ Forecaster Papin |
