An EFAS Flash Flood Notification is sent out to the affected EFAS partner if the probability of exceeding the 5-year return period of the ERIC indicator is equal or greater than 30%. Additionally, the lead time for the start of the event, i.e. the time lag between the start of the model run and the point where 30 % of the probabilistic forecasts exceed the 5-year return period threshold, may not be longer than 48 hours. Flash Flood Notifications are sent for catchments smaller than 2000 km2. Those notifications are issued for administrative regions and are sent to the affected partner only since they reflect rather local phenomena, i.e. they are not sent to partners having a share in the concerned river basin.

EFAS Flash Flood Notification email

Besides country and administrative region(s), the likely start of the event and probabilities of the 5- and 20-year return period exceedances of the ERIC indicator based on the COSMO-LEPS forecast are indicated in the email. Additional information includes the forecast date and the affected area susceptible to landslides. The forecast date refers to the model run when criteria were fulfilled.

The "affected area susceptible to landslides" is based on the European landslide susceptibility map, which itself categorizes the European land area into 5 classes from very low to very high. This classification is basically - and very much simplified - a function of slope and soil properties. To derive the "affected area susceptible to landslides" for the Flash Flood notification, the area highlighted in EFAS where flash flooding can be expected (see "ERIC Affected Area"-layer in the EFAS Map Viewer) is intersected with the landslide susceptibility map. We only list the categories moderate, high and very high and the resulting area share for the flash flood affected area. An area of 0 km² for one of the categories means that there is no part of the area potentially affected by flash flooding that falls into this particular class.

Using the links in the e-mail, the partner can navigate to the EFAS IS, EFAS wiki or to the feedback collection (see section 4.4). As for Formal and Informal Notifications, only one notification is issued for each event.