TABLE D.2 Example of Format for Reporting Preliminary Flash Flood Warning Verification Statistics

Preliminary Verification Statistics

Flash floods

Number of warnings issued


Number of verified warnings


Number of unverified warnings


Number of events


Number of events with warnings


Number of events without warnings


Average lead time


Probability of detection


False alarm rate


Critical success index


  • one or more dates (select beginning and ending date);

  • one or more counties, WFOs, states, NWS regions, or the contiguous United States.

Backup Mode for Warnings

When a WFO goes into backup mode, FFWs are still sorted by county, so all FFWs issued by the backup office are attributed to the primary WFO.

Preliminary Flash Flood Warning Reports

The regional headquarters will report to the OCWWS Performance Branch no later than the 14th of each month preliminary flash flood warning verification statistics for the previous month. When the 14th of the month falls on a weekend or holiday, the statistics are due the last business day prior to the 14th. Present the statistics in the format given in Table D.2. The OCWWS Performance Branch subsequently collates the regional data into a national summary.

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