Is it likely that unusually wet or dry conditions will continue?

This map shows where and how likely recent wet or dry conditions will continue over the next 3 months.

Green areas indicate where the last 3 months have been unusually wet and where the coming 3 months are likely to be unusually wet. Lighter green indicates a slightly enhanced chance and dark green indicates a greatly enhanced chance of unusually wet conditions continuing. Yellow and orange areas indicate where the last 3 months have been unusually dry and where the coming 3 months are likely to continue to be unusually dry. Yellow indicates where currently dry conditions have a slightly enhanced chance of continuing, and orange indicates where dry conditions have a greatly enhanced chance of continuing over the next 3 months.

This forecast shows only the likelihood of 3-month accumulated rainfall (or snow) being unusually high or low, and does not indicate chances of individual heavy rainfall events. The forecasts apply over large areas only, and should not be used to forecast local conditions, or as a flood forecast.

Dataset Documentation

IRI Predictions in Context (PiC)
Data Forecast data: Dominant tercile probabilities for seasonal (3-month) precipitation for the first lead time from the IRI Net Assessment Forecast, issued every month at 2.5° lat/lon resolution; Observational data: CAMS-OPI monthly observed precipitation gridded at 2.5° lat/lon resolution
Data Source Analysis data: International Research Institute for Climate and Society, Predictions in Context, Map Room PiC page, Data Library entry; Forecast data: International Research Institute for Climate and Society, Net Assessment Forecasts, Map Room Forecast page, Data Library entry; Observational data: NOAA, Climate Prediction Center, CAMS-OPI Precipitation
Analysis Shaded areas on the "Same Tendency" map indicate locations where the IRI Net Assessment seasonal precipitation forecast for the next 3-month season shows an enhanced likelihood of above-normal (below-normal) precipitation AND where precipitation received in the 3-month season before the forecast was issued was also above normal (below normal), i.e., the forecast has the same tendency as the previously observed precipitation.

Help

Contact help@iri.columbia.edu with any technical questions or problems with this Map Room, for example, the forecasts not displaying or updating properly.

How to use this interactive map

Switch to another map: Select the dropdown menu at the top of the page, to the right of the blue “Forecasts” heading.

Return to the menu page: Click the blue link called “Forecasts” at the top left corner of the page.

Zoom in to a region:
Method 1: Pick a region from the list:

1. Select the dropdown menu at the top of the page, titled “Region”
2. Click on the region of interest, and the map will automatically refresh.

Method 2: Click-and-drag:

1. Click the left mouse button at the upper-left corner of the region to which you would like to zoom.
2. While holding down the button, drag the mouse to the lower-right corner of the region to which you would like to zoom.
3. Release the left mouse button. The map will redraw automatically.

Zoom out to the global map:

1. Move your mouse over the map, until you see three icons appear in the upper left corner.
2. Click the icon of the magnifying glass.
3. The map will redraw automatically. Note that the map cannot display areas outside of the latitudes initially shown on the interface (about 66.25S – 76.25N).

Change the date of the forecast: Forecasts are labeled by the month they were issued. You can find this label by moving your mouse over the map until you see a text box appear at the top with the date inside.

1. To step forward or back by one month, click the corresponding buttons to the left or right of the text box, and the map will automatically refresh.
2. To manually change the forecast issue date, type your date of interest into the text box. This must follow the format: “Jan 2008”. Then, press “enter” or click the “refresh” icon in the top left corner of the map.
3. To produce an animation of these maps over a series of dates, type the date range into the text box. This must follow the format: “start date” followed by “to” followed by “end date”. For example “Jan 2008 to Dec 2008”.