The field guide · Sun
Space weather alerts: watch, warning or alert?
A watch signals increased risk while timing or occurrence remains uncertain. A warning concerns activity that is imminent, likely or occurring. An alert reports that an observed condition has crossed a threshold or an event has begun. The words describe different evidence states.
Three messages, three jobs
The US National Weather Service defines these terms for space weather. A watch gives earlier notice of potential activity. A warning is a shorter-term, higher-confidence message. An alert concerns an observed threshold or an event already under way.
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| Message | Main question it answers | What to check next |
|---|---|---|
| Watch | Is the risk elevated for an upcoming period? | Forecast window and later updates |
| Warning | Is significant activity expected soon or occurring? | Valid interval and stated threshold |
| Alert | Has an observed threshold been crossed? | Observation time and event category |
The messages are not three interchangeable names for “a storm is happening right now.” An old alert can remain in an archive long after the relevant interval ends.
Read five parts of the bulletin
First, identify the issuing organization. Then read the issue time, valid or observed interval, scale letter and severity. Finally, look for a revision, continuation or cancellation.
This sequence protects against a common mistake: interpreting the time a post was shared as the time an instrument observed the event. It also prevents a forecast for tomorrow from being presented as today’s measurement.
Keep G, R and S attached to the number
A G message concerns geomagnetic storms. R concerns radio blackouts. S concerns solar radiation storms. A headline that drops the letter loses information about the phenomenon and its possible effects.
Our space-weather overview introduces the three families. The solar-radiation guide explains why an S event is a particle measurement rather than a Kp reading.
A worked reading example
Imagine a message labelled “G2 watch, valid tomorrow,” followed later by “G1 threshold reached, 18:00 UTC.” This is an invented example, not a live bulletin. The first message describes a forecast risk. The second describes an observed threshold. Neither tells you what the latest reading is several hours after 18:00.
A useful summary would preserve both statements and their times. It would not claim that the G2 forecast had already happened or that the G1 observation remained current indefinitely.
Where to find the original messages
Use NOAA’s alerts, watches and warnings page for the original products. A notification from an app is a convenient prompt to inspect context; it should retain source and time rather than replacing the underlying bulletin.
Schumann Pulse’s optional activity notifications are product features, not official emergency warnings. Personal notification settings do not change the underlying scientific event.
Sources
- National Weather Service: space-weather watch, warning and alert definitions.
- NOAA SWPC: original bulletin products.
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