Nimrod rainfall forecasting system overview

Nimrod overview

Operational in UK since 1997 Operational domain Poland: 1600 x 1600 km Analyses synoptic reports, radar, satellite, NWP and previous Nimrod nowcast 2D-VAR Nowcasts optimum combination of observation extrapolation & NWP resolution: 4 km, 15 minute range: T+6 hours

Nimrod data I/O

Nimrod radar data processing in UK

Nimrod Forecasts

Rainfall rate and accumulation Probability of snow Precipitation type

Nimrod rainfall forecast scheme

Identify rain objects in rain analysis Identify optimum method of moving rain objects Cross-correlation NWP wind vector Generate an extrapolation forecast using optimum vectors for each rain object Merge extrapolation forecast with NWP rain forecast infill missing data areas in extrapolation forecast introduces growth and / or decay into forecast ensures continuity between forecast products

Nimrod extrapolation and 'merged' forecasts

Dissemination

RAINBOW Nimrod format - binary, header followed by integer or real data array Text GIF / PNG - monitor pages

Progress

Tasks completed or almost complete processing of GRIB / BUFR inputs processing of Meteosat-7 VIS and IR processing of synoptic weather reports modifications to rain analysis / forecast to run on new domain Nimrod monitor Tasks still to do radar processing NWP processing heavy rain warning messages precipitation type forecast