Synoptic causes of torrential rainfall in South-eastern Spain (1941–2017)

Abstract

The weather types of 68 dates with torrential rainfall (≥200 mm/day) recorded at any weather station in the provinces of Alicante or Murcia during the period between 1941 and 2017 were determined using the Martín-Vide’s 1984 manual synoptic classification. Other relevant synoptic characteristics, as well as the surface pressure, and the value of the Western Mediterranean Oscillation index (WeMOi) on which those dates fell were also considered. The results show the high percentage of the Advection from the East with DANA (isolated high-altitude depression) or ‘gota fría’ type, which is present in more than 50% of the events, followed by the Trough type at 500 hPa and the Dynamic or Cold-core Low type, in the torrential rainfalls of South-eastern Spain. Except for the latter type, the average air pressure is close to or higher than normal. The WeMOi was negative for all events, which is consistent with the nature of this teleconnection pattern.

Synoptic Causes of Torrential Rainfall in the Balearic Islands (1941–2010)

“…One can compare the torrential episodes in the Balearics with those analysed by Martin-Vide et al [24] in the SE Iberian Peninsula that show similarities and differences between the two locations. The seasonal distribution for the number of episodes is very similar, with the autumn maximum standing out (62.3% in the Balearics and 69.1% in the SE Peninsula).…”

“…Isolated depression at high level configurations has a major impact on the creation of intense precipitation episodes. This may reach extreme instances such as in the SE Iberian Peninsula [24] where a specific synoptic situation, easterly advections accompanied by a DANA, underlie over half of all torrential days. Notwithstanding this, the presence of an isolated configuration is not as predominant in the Balearic Islands.…”

“…The situations mostly matched 1 of the 16 situations set out in the cited work, with four case outliers that were identified as belonging to two configurations that do not appear in said classification (NE advection and NE advection with DANA). Whilst following the practice of other work using the same classification [24], the term "gota fría" (cut-off low) [31,32] was replaced for the term DANA (Isolated Depression at High Levels). -Characterising the synoptic situations whilst noting certain relevant features at continental scale, as well as atmospheric pressure in the area of study.…”

“…The main aim of this study is to determine the synoptic situations that have produced torrential events of 200 mm/day or more in the Balearic Islands during the 70-year period between 1941 and 2010. Values above 200 mm normally correspond to flood episodes, and have usually been considered as a critical limit of torrential rainfall [7,8,22,24].…”

“…With regard to manual synoptic classification methods (subjective), Martin-Vide et al [24] recently applied the method put forward by Martin-Vide [17] for 68 precipitation episodes of over 200 mm/day in the provinces of Alicante and Murcia (SE Spain) during the 1941-2017 period, combining the test with values from the Western Mediterranean Oscillation Index (WeMOi) for the same days. In reality, subjective classifications, whether for weather types or synoptic situations per se, were trialled for Spain and its regions by authors including Fernández [25], Clavero and Raso [26], Martin-Vide [17], Romero et al [12], Capel-Molina [27] and Martin-Vide and Olcina [28].…”