Ensemble sea level forecast, 48 hours ahead
Ensemble high water risk forecast, 48 hours ahead
Both
Ensemble spread indicator

The DKSS storm surge model is forced by an ensemble of DINEA weather model forecasts, including the deterministic forecast. Results are presented graphically for danish tide gauge stations, and may be used as indicating

• uncertainty of sea level forecast (= ensemble spread)
• probability of exceedance of warning levels (= number of ensembles in excess
• position of deterministic forecast within the ensemble
• ensemble median forecast

• DKSS storm surge model set-up (geography etc.)
• Atlantic surge model for boundaries
• ECMWF global deterministic NWP model
• HBM ocean model
• DMI-Harmonie DINEA/EPS NWP ensemble prediction system

DKSS-EPS has 31 ensemble members, forced by the NWP ensemble prediction system DMI-DINEA/EPS, plus one deterministic member. DINEA/EPS is based on the NWP model UWC-Harmonie DINI. The perturbation lies with the weather forcing exclusively.

DMI-DINEA/EPS ensemble members are all Harmonie-NEA.

The weather model ensemble forecast range is 60 hours. The ensembles are arranged to have 5 ensembles run every hour, with the deteministic model run every hour. In a six-hour scedule, this produces 31 ensemble members, with forecast range relative to the analysis time of latest member ranging from 60 hours (newest) to 54 hours (oldest). With the storm surge ensembles run on a standard 6-hour schedule, 51 hours is the chosen limiting range. It might be possible to increase to 54 hours.

The ensemble graphics page shows sea level ensemble results for primary stations (no duplicate stations). We show

• deteministic forecast
• ensemble mean
• ensemble min
• ensemble max
• ensemble spread

The risk graphics page shows percentage of ensembles exceeding warning sea level for primary stations (no duplicate stations).

This page shows both.

• platform: UWC aurora
• cpus: 128 (1 node)
• runtime: 2 hours
• schedule: 6 hours, at 03, 09, 15, 21 utc
• ready at: 05, 11, 17, 23 utc
• forecast range: 48 hours

Proper operationalisation. This is, until further notice, pre-operational, running on the research cluster of the UWC Cray-hpc. And as such not monitored 24/7 by duty staff.

Schedule like DINEA/EPS, running five ensembles every hour.

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Jacob Woge Nielsen - 23 Sep 2025