The post-tropical depression Gabrielle brought a break in the warm temperatures over the weekend, which had marked the start of this fall. With heavy rains and numerous incidents recorded in the North, the phenomenon reached the mainland after causing some displacements in the Azores—where it landed with greater intensity than anticipated—before heading towards Spain.
Though the hurricane’s effects were limited to the weekend, several details might have gone unnoticed, such as the strongest gusts of wind.
The Portuguese Institute of the Sea and the Atmosphere (IPMA) conducted an analysis, emphasizing that the data is preliminary and will be re-evaluated.
Strongest Gust on Mainland was 105 km/h
In its analysis, experts noted that landfall occurred in the Aveiro region around 5 a.m. on Sunday, with the storm’s approach prompting the usage of umbrellas by Saturday afternoon.
“As frequently happens with this type of meteorological systems, it was observed that propagation over land, partly due to friction with the surface, was relatively slow (about 25 km/h). This factor, along with each area’s position in relation to precipitation bands, determined the distribution of accumulated rainfall. In this context, the regions of Minho, Douro Litoral, and Beira Litoral saw the most significant values,” reads a note on the IPMA website.
Regarding precipitation, the highest hourly value was recorded at the Porto-Gens station, “with 15.5 mm (between 01 and 02 UTC on the 28th. In the 6-hour period of highest precipitation, between 22 UTC on the 27th and 04 UTC on the 28th, values reached almost 70 mm in the Porto region. This perspective was captured by observations from the Arouca radar, although these values are typically lower than those observed on the surface.” Precipitation was lighter elsewhere, particularly in the southern regions.
In addition to rainfall, which prompted a red alert for Porto, Gabrielle brought strong winds… but where?
IPMA specialists highlighted that the tropical origin of this storm “naturally supported a turbulent wind regime, with gusts approaching and sometimes exceeding 100 km/h at higher altitudes.” The strongest gust recorded on Sunday, the 28th, as the storm moved southeast, was 105.5 km/h in Fóia, Serra de Monchique, Algarve.
“The highest instant wind values on the 27th, while the depression was still over the Atlantic, were observed at Pampilhosa da Serra (97.9 km/h, at 20 UTC) and Cabo da Roca (82.1 km/h, at 13:20 UTC), attributed to exposure and higher altitude in the former case and proximity to the sea and local effects in the latter,” they detail.
Before the Mainland, the Azores
Before heading to Spain, Gabrielle passed through the Azores archipelago, leaving at least 16 people homeless amidst hundreds of incidents. The phenomenon reached the archipelago with more force than initially anticipated, escalating from a tropical depression to a hurricane and finally to a post-tropical cyclone, entering this category about 250 km/h south of the island of Flores.
“The most significant parameter associated with storm Gabrielle was the wind. In this case, the central group was broadly subject to stronger flows, both in terms of maximum instant wind values (gusts) and persistent average wind,” details the IPMA, noting that this was “also the group where the highest values in this event were observed between low-altitude stations.”
“Indeed, the Horta/Príncipe Alberto do Mónaco station, practically at sea level, recorded 146 km/h (between 4 and 5 UTC) and 154 km/h (between 5 and 6 UTC). At the Santa Bárbara station (owned by the Angra do Heroísmo Municipal Council), a high value of 185 km/h (between 4 and 5 UTC) was observed, but at higher altitudes,” IPMA reports.
