Freezing Rain report
2018-03-16 (IPMA)
Following the invitation made by IPMA on 06-03-2018 to its meteorological information users, in order to share information on the phenomenon of freezing rain, an analysis was carried considering the following elements:
- Observations at the IPMA’s weather stations network;
- Hourly analysis of the 2 m temperature by a statistical adjustment of observations and a short-term forecast (CANARI-AROME Analysis);
- Reports sent by the users.
Taking into account the above elements of analysis and considering as a necessary condition the occurrence of minimum air temperatures equal or lower than 0°C, it was concluded that:
- The areas with the most favorable conditions for the phenomenon of freezing rain were mainly the districts of Viseu and Guarda.
- The districts of Vila Real and Bragança have been mainly affected by snowfall.
- However, it is not excluded that the phenomenon might occurred locally in another inland areas of the North and Center mainland Portugal.
From the analysis of figure 1 it can be seen that the majority of the reports of freezing rain made by the users is included on the area with minimum air temperatures equal or lower than 0°C. However, some reports are not included in this area, which may be explained by one or more of the following reasons:
- Incorrect spatio-temporal reference of the report by the user;
- Incorrect identification of the phenomenon by the user (including situations where the occurrence of rain was preceded by snowfall);
- Localized occurrence of negative air temperatures in areas of complex orography, which are not covered by the IPMA’s weather stations and/or are not resolved by the model.
Imagens associadas
Figura 1 - Spatial distribution of the reports of freezing rain made by the users (blue dots) and 0°C isotherm of the minimum air temperature (magenta line) on 27 February (left) and 28 February (right). The area with negative/positive temperatures is on the right/left side of the mentioned isotherm. The 0°C isotherm was obtained using the observations of the 2 m minimum temperature and the results of the CANARI-AROME analysis.
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