# Publicly available data set with ensemble forecasts and observations?

I am looking for a publicly available, easy to download, small data set of ensemble forecasts (or reforecasts), with corresponding observations or reanalysis. We are planning to illustrate some methods for a small software package, so ideally, the data set should be available for the foreseeable future, or even better, freely distributable. Further, ideally, the data set would be given as SV or text file (anything that can be read easily without requiring additional software packages, as it would be the case with GRIB for example). Any suggestions?

By easy to download I mean: Ideally, without creating any login, for example directly possible within Python or R; small in the sense of a couple of months and data for only one location are enough; there should be some verifying observation or re-analysis associated with the forecasts

• Welcome to Earth Science SE! Easy to download means 'without creating a login' or 'download by a web interface'? Please define 'small'. Should it be a global or a regional data set or should it be data at one specific location (where also measurements are available)? – daniel.neumann Jul 6 '16 at 7:59
• @daniel.neumann I have added some details to the question – user3825755 Jul 6 '16 at 8:04
• I've never seen "small data set" and "ensemble forecast" used in the same sentence before. I would suggest atmos.washington.edu/~ens/uwme.cgi but their verification page is still under construction. – farrenthorpe Jul 6 '16 at 21:20
• @farrenthorpe I have also never used these terms in one sentence before, the reason here is that we are only looking for a small illustrative example for some software package. Thanks for the link to the UWME data, however, I do not see any option to download any data there – user3825755 Jul 7 '16 at 7:30
• NCEP's NOMADS server hosts the GFS ensemble forecasts output, you can get them here: nomads.ncdc.noaa.gov/data.php?name=access#EnsembProb. The data is in grib format, that is something you will have to deal with. Model output is almost never distributed as plain text for practical reasons. Observations from NOAA land stations and NDBC buoys are also publicly available. Google is your friend. – milancurcic Jul 7 '16 at 16:07

For the historic forecasts check out the Global Ensemble Forecast System (GEFS) from NOAA. It has historic forecasts going back to 2015. For validation try Daymet (North American only) or PRISM (continental USA only) for gridded temperature and precip from historic observations.

The GEFS data is in GRIB format. But thats just something you can't get around. The European climate center (ECMWF) have their own suite of commands in a program called grib_api, which includes a handy GRIB to netCDF converter if that's a format your more familiar with.

All of these are free to download without signing up for anything. The GEFS data is also available through the R package rnoaa, and the PRISM has it's own R package prism.

You can try if this looks simple enough. Still requires registration, but it is free for reasonable use: Global Ensemble Forecast System (GEFS).