Hndcasts are produced in the same way as the real-time forecasts but for past dates. ******Each model version includes forecasts for past years, called “hindcasts” that can be compared to the historical record. They are available at the same temporal and spatial resolution as forecasts. We ensure that the model has not seen any data from the valid forecast period so there is no unfair advantage. For example a 2010 forecast is determined from the 1980-2009 climatology.
<aside> 💡 Note: Due to the inclusion of ECMWF ENS in v9, the sub-seasonal reforecast schedule has been augmented from previous versions. The ENS reforecast is produced in real time on Mondays and Thursdays, with initializations at constant calendar dates over the past 20 years.
To accommodate this, the Salient Blend reforecast schedule has been updated to include forecasts on both the ENS schedule and the GEFS Wednesday reforecast schedule. Individual model forecasts are only used in the Salient Blend if they are no more than 1 day out of date. This means that for many of the reforecast dates, only one of ENS or GEFS are used. For January 2000 to June 2003, only GEFS is used in the Salient Blend, and for January 2020 to October 2020, only ENS is used in the blend.
</aside>
API model: gem
| Timescale (UI) | API timescale |
Hindcasts |
|---|---|---|
| Daily | daily | 2020-10-16 to 2025-04-04 |
API model: blend
| Timescale (UI) | API timescale |
Hindcasts |
|---|---|---|
| Weekly rolling | sub-seasonal | 2000 onward |
| Weekly calendar | weekly | 2000 onward |
| Monthly rolling | seasonal | 2000 onward |
| Monthly calendar | monthly | 2000 onward |
| Quarterly rolling | long-range | 1981 onward |
| Quarterly calendar | quarterly | 1981 onward |
Hindcasts are available for all models except ECMWF ENS 15.
<aside> 📌
The GEFS hindcast is missing data between 2019-12-21 and 2020-10-12. The reason is because the GEFS version we use was "operationalized" in late 2020, and they produced a "reforecast" from 2000-2019.
ECMWF ENS only run the reforecast for a given model version back 20 years, and since the current version started running in 2003, the ECMWF ENS hindcasts start in 2003-06-29
</aside>
| Model Name | API model |
Hindcasts |
|---|---|---|
| NOAA GFS v16 Global Forecast System | noaa_gfs | May 19, 2021 onward |
| NOAA GEFS v12 Global Ensemble Forecast System | noaa_gefs | 2000 + (missing data between 2019-12-21 and 2020-10-12) |
| ECMWF SEAS5 5th generation seasonal | ecmwf_seas5ecmwf_seas5_calib | 2000 + (months) 1981 + (quarters) |
| ECMWF ENS ** extended range | ecmwf_ens ecmwf_ens_calib | June 29, 2023 onward |