This subseasonal forecasting system consists of probabilistic precipitation forecasts based on the full probability distribution.
Probabilistic subseasonal forecasts from a multi-model ensemble provide reliable information to the forecasting community. The multiple models ensemble uses statistical recalibration, based on the historical performance of those models. The flexible use of probability distributions allows for the delivery of interactive maps and point distributions that become relevant to the needs determined by the user.
The “Most Likely Forecast [mm]” map on the right shows the most likely (median) weekly precipitation forecast in mm as colors.
The “IQR [mm]” map on the left illustrates the uncertainty associated with the median. The “IQR [mm]” map appears only when the forecast is shown in terms of the median (more information on the different forecasts is below in the section on controls).
Controls (at the top of the page):
Forecast Issued / Target Period: Before May 1, 2021, the climatological period is 1999-2014; After May 1, 2021, the climatological period is 1999-2016. What makes the forecast flexible is that underlying the default map is the full probability distribution for forecast and weather. Therefore, the user can specify the historical percentile or a quantitative value (here precipitation in mm/week) for the probability of exceedance or non-exceedance.
Forecast:
Clicking on a point on the map will display the local cumulative distribution and probability distribution functions of the forecast (green) along with the climatological distribution (black dots).
Distribution parameters: The ELR parameters of the climatological observed reference and the forecast for each model are available here.
Contact help@iri.columbia.edu with any technical questions or problems with this Map Room.