Three probability categories are defined:

If the potential exists for precipitation exceeding guidance values, but the expected probability is less than 5%, WPC will place the words SEE TEXT over the threat area. This area will then be referenced in the excessive rainfall discussion.

In addition, areas where precipitation is expected to exceed five inches will also be indicated.

If conditions are not favorable or are not expected to become favorable for flash flooding then "Rainfall Not Expected To Exceed Flash Flood Guidance" is appended to the graphic.

The graphics and associated discussion are issued four times per day, at 03, 06, 15, and 18 UTC. The valid times of the products varies as noted in the table below. The 03 and 15 UTC issuances are valid for 21-hour periods, while the 06 and 18 UTC issuances are valid for 30 hours. In addition, if significant changes to the outlook are necessary, the forecaster has the option to issue products at 00, 12, and 21 UTC.

Note: The definition of exceeding flash flood guidance is broad. Flash flood guidance values depict the amount of rainfall necessary in a specific period of time to cause flash flooding over a given area. The River Forecast Centers typically issue guidance values for 1-, 3-, and 6-hour periods, and in some cases, 12- and 24-hour periods. WPC forecasters make a determination of the threat that precipitation will exceed any of the 1-hour, 3-hour, or 6-hour FFG values associated with the specific time interval in the valid time period of the forecast. This product is not intended as a specific forecast of flash flooding, but rather as a probabilistic indicator of rainfall amounts exceeding flash flood guidance over an area.