Prog charts forecasts are valid at the time printed on the chart. For example, a prog chart that says it is valid at 06Z on November 12 (Valid 06Z on Tuesday November 12, 2024) is valid at 06:00Z on November 12.
In contrast, the valid time shown on the 12 HR Probability of Precipitation (PoP) charts is the ending time of the 12-hour valid period.
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