JMA routinely conducts long-range forecasting and issues monthly outlook, three-month outlook and warm/cold-season outlook. Please refer to calendar of these outlooks.
Forecasts of individual elements are given in the three categories of below normal, near normal and above normal. The thresholds of each category are determined so that the climatological chance of occurrence for each category is 33.3% for the period from 1991 to 2020.
JMA employs a dynamical method as a major long-range forecast technique. An outline of the operational ensemble prediction system is given on the Model Outline page. Empirical/statistical methods including Canonical Correlation Analysis and Optimal Climate Normals are also used for preparing the three-month outlook, the warm-season outlook and the cold-season outlooks.
Note: Figures of outgoing longwave radiation (OLR) in Monthly Report over Japan
are based on the NOAA CPC Blended OLR data from the September 2023 report,
while they were based on the NOAA CPC AVHRR OLR data until the August 2023 report. (16 October 2023)
Please refer to the Monthly Discussion on Seasonal Climate Outlooks, a new comprehensive document intended to assist National Meteorological and Hydrological Services (NMHSs) in the Asia-Pacific region in interpreting and assessing WMC Tokyo's products for three-month prediction and warm/cold season prediction and in understanding the current conditions of the climate system.