Read the two labels
NOAA’s Ocean Prediction Center defines issued as the dissemination time and valid as the date and time represented by the forecast. Its products use a stated reference time. These labels serve different purposes: one dates the product’s publication, while the other locates the forecast conditions in time.
Preserve the date as well as the hour. A forecast valid after midnight can belong to another calendar day even if the graphic is discussed during an earlier programme.
Distinguish analysis from forecast
An analysis and a forecast can use similar symbols while describing different evidential tasks. The Center’s graphical verification tool asks users to match valid times when comparing an analysis with an earlier forecast. Comparing unmatched times would test different weather situations rather than the forecast for the same instant.
When a presenter advances an animation, follow the time label on each frame. The programme’s live clock can remain current while the map moves into future periods or back through earlier observations.
Check the product and quantity
Read whether the map concerns surface conditions, an upper-air level, wind, waves or another variable. A pressure pattern and a precipitation graphic are not interchangeable. Keep units and legend with the timestamp, especially when a screenshot crops the source information.
A model run time can also differ from the product’s issue time and its valid time. Use the source’s definitions instead of assuming every timestamp on the screen describes the same event.
Use it within the programme’s scope
For a historical broadcast, save the chart’s original issue and valid times with the episode date. For current planning, consult the relevant official service’s latest product and instructions; this article provides no forecast or operational assessment.
When sharing, state whether the image is an analysis or forecast and what time it represents. If converting UTC, use the actual date and intended location rather than one fixed Canada-wide offset. A clear note prevents an old forecast from being presented as an observation and prevents a forecast for tomorrow from being described as weather occurring at the moment the television programme was recorded.
Related questions
Is issued time the forecast’s target time?
No. Valid time identifies the represented conditions.
How should I compare a forecast with an analysis?
Use the same valid time and compatible products.
Sources and scope
Scope notes distinguish published documentation, supplied information and editorial methods. They do not report a hands-on service test.
- NOAA OPC chart FAQ — Defines issued and valid labels; unrelated outdated clock wording not relied on.
- NOAA graphical forecast verification — Explicitly requires matching valid times for comparison.
