Japan Meteorological Agency Ensemble Prediction System Website - EPSWEB

This website provides products derived from the Ensemble Prediction System (EPS) of Japan Meteorological Agency (JMA) to National Meteorological and Hydrological Services (NMHSs), as part of a pilot project of JMA aiming at improving the EPS and increasing the availability of its products.

For further improvement of JMA's EPS and its products, users' feedback, especially on comparison of EPS products with local observation and actual weather, is welcomed and should be directed to the following email address: eps-admin@naps.kishou.go.jp .

Information on this website is guidance and intended to be provided for use by forecasters and meteorologists in NMHSs. Please consult your national meteorological agency/administration for official forecasts of your country, region and/or local area.

Global Ensemble Prediction System products

Weather Chart Guidance "Stamp maps" ( WPacific , Asia , SouthChinaSea)
Probability Guidance "Probability maps" ( WPacific , Asia )
Time-series Point Guidance "EPSgram"

Guidelines and Training Materials (Related Links)

"Guidelines on Ensemble Prediction Systems and Forecasting (EPS) - WMO No.1091" in WMO publication
"Guidelines on Ensemble Prediction System Postprocessing - WMO No.1254" in WMO publication
"Ensemble Forecasting Explained" operated by the COMET program

Global Ensemble Prediction System of JMA

The Global Ensemble Prediction System (GEPS) was introduced in 2017.
A low-resolution version(*) of JMA’s Global Spectral Model (GSM) is used in the GEPS. The GEPS runs up to 11 days twice a day at 00 UTC and 12 UTC, 18 days once a day at 12 UTC, and 34 days twice a week. The numbers of GEPS ensemble members per initial time is 51(**) for forecasts with lead time up to 18 days, and 25(***) for forecasts with longer than 18 days.

This website provides products derived from the GEPS for forecasts with lead time up to 11 days.

(*) TQ479 for forecasts with lead time up to 18 days, and TQ319 for forecasts with longer than 18 days
(**) one unperturbed forecast, and forecasts from 50 perturbed initial fields generated by the Singular Vector (SV) method and the LETKF approach
(***) one unperturbed forecast, and forecasts from 24 perturbed initial fields generated by the Singular Vector (SV) method and the LETKF approach

Specifications of the NWP models and the EPSs at JMA

Legal Notice

[Copyright]: The material contained on this website (eps.kishou.go.jp) is protected by the Copyright Law of Japan and related International laws and may not be reproduced or used for any purposes without permission.

[Disclaimer]: a) JMA shall not warrant accuracy and quality of products provided through the EPSWEB.
b) JMA shall have neither assumes liability nor responsibility for any problems arising from the use of those products provided through the EPSWEB.

[Alteration of services]: a) JMA may terminate the EPSWEB service without prior notification.
b) JMA may change the content of data provided through the EPSWEB without prior notification.

[Linking to this website]: Anylinks to this website without our permission are prohibited.