Subtropical Storm Alpha (2020) located in/on physical feature Portugal
Meteorological history
Alpha originated from a large, extratropical low-pressure area, which developed over the Northeastern Atlantic Ocean on 14 September. As a strong upper-level trough dug southeastward and became a cut-off low about 500 nmi (580 mi; 930 km) north of the Azores, the interaction between the low and a surface front promoted the formation of a strong frontal low, which rapidly deepened and reached its extratropical peak that day, with maximum 1-minute sustained winds as high as 112 km/h (70 mph) and a minimum central atmospheric pressure of 992 mbar (29.3 inHg). By this time, the extratropical cyclone had a very large radius of gale-force winds expanding over 500 km (270 nmi; 310 mi) from its center of circulation. The low was initially very slow-moving, but began to dip southeastward and weaken by 15 September when the National Hurricane Center (NHC) first began to monitor the system for possible development into a tropical or subtropical cyclone. This was because the system was expected to track close to a region of unusually-warm sea surface temperatures to the west of Portugal of around 22 °C (72 °F), though these temperatures would still typically be too cold to support tropical cyclogenesis.The size of the low's wind field continued gradually decreasing on 16 September, as some of its frontal features gradually became less defined, although the NHC only highlighted a low (20%) chance of development at this time, operationally. Nonetheless, convection, or thunderstorm activity, became more concentrated and organized near the center of the low, and a newly formed central low soon became the dominant feature within the larger extratropical system. In post-season analysis, the NHC estimated that Alpha had developed as a subtropical storm at 06:00 UTC on 17 September, as the thunderstorm activity associated with the smaller low feature became well-organized. Alpha accelerated to the northeast, and a combination of radar imagery from Portugal, scatterometer passes, and satellite-derived wind data revealed Subtropical Storm Alpha had peaked around 00:00 UTC on 18 September, just about 417 km (225 nmi; 259 mi) off the coast of Portugal, while the storm was producing 1-minute sustained winds up to 80 km/h (50 mph).Alpha maintained its intensity up to its landfall about 17 km (11 mi) south of Figueira da Foz, Portugal, around 18:40 UTC that day. The storm's final minimum central pressure estimate of 996 mbar (29.4 inHg) was based on a surface pressure of 999 mbar (29.5 inHg) being recorded in Monte Real, Portugal, well north of the cyclone's landfall point. After landfall, the small low-level circulation associated with Alpha began to quickly decay, as the storm moved inland, and the cyclone weakened to a subtropical depression at 0:00 UTC on 19 September. Alpha degenerated into a remnant low later that day, as it moved over the mountainous terrain of Northeastern Portugal.
situated in/on physical feature positioned in/on physical feature found in/on physical feature placed in/on physical feature situated on/at physical feature