Warnings
The Meteorological Office of the Velocity Interoperability Network warns member organisations and citizens of the Network of weather that is likely to cause disruption, damage or danger. Warnings are issued at four levels for eight hazards, are published on this site and are sent by email to those who have registered for the service.
No warning is in force
A warning is not a forecast of what will probably happen; it is a statement that hazardous weather is possible enough, and would matter enough, that those affected should act. The level of a warning combines the likelihood of the weather with the impact it would have. The forecast in force is always to be read alongside any warning; the schedule of forecasts is set out on the Forecasts page.
The warning levels. The four levels below are used for every hazard. The action expected is the minimum; member organisations may set stricter rules for their own sites.
| Level | Name | Meaning | Action expected | Usual notice |
|---|---|---|---|---|
| Level 1 | Advisory | Weather that may cause minor disruption to travel, outdoor work or services at some sites. | Be aware. Check the forecast before travelling or working outdoors. | 24 to 48 hours |
| Level 2 | Warning | Weather likely to disrupt travel, outdoor work or services across part of the Network. | Be prepared. Member organisations review continuity plans; outdoor work is reassessed. | 12 to 36 hours |
| Level 3 | Severe Warning | Dangerous weather expected to cause serious disruption and a risk of injury or damage. | Take action. Sites may close or restrict access; non-essential travel is deferred. | 6 to 24 hours |
| Level 4 | Emergency Warning | Weather posing a threat to life across the area warned for. | Act immediately on the instructions of the Emergency Management Department. | As soon as identified |
Indicative criteria. The thresholds below indicate the weather at which a warning at each level is normally considered. They are a guide, not a rule: the forecaster may issue a warning at a higher level where the ground is already saturated, where the weather falls at a time of heavy travel, or where several hazards coincide. Level 4 has no fixed threshold and is issued only where there is a threat to life.
| Hazard | Level 1 Advisory | Level 2 Warning | Level 3 Severe Warning |
|---|---|---|---|
| Strong wind | Gusts of 70 km/h | Gusts of 90 km/h | Gusts of 110 km/h |
| Heavy rain and flooding | 30 mm in 24 hours | 50 mm in 24 hours, or 25 mm in 3 hours | 80 mm in 24 hours, or 40 mm in 3 hours |
| Snow and ice | Snow settling, or ice on untreated surfaces | 5 cm of snow, or widespread ice | 15 cm of snow, or ice persisting through the day |
| Fog | Visibility below 200 m for 3 hours | Visibility below 100 m for 6 hours | Visibility below 50 m across the Network |
| Thunderstorms | Isolated storms with lightning | Frequent lightning, hail or gusts of 70 km/h | Severe storms with large hail or gusts of 90 km/h |
| Extreme heat | Maximum of 30 °C on 2 consecutive days | Maximum of 33 °C on 2 consecutive days | Maximum of 36 °C on 2 consecutive days |
| Extreme cold | Minimum of −5 °C | Minimum of −10 °C | Minimum of −15 °C |
| Coastal storm surge | Water level 0.3 m above predicted high water | Water level 0.6 m above predicted high water | Water level 1.0 m above predicted high water |
The hazards warned for. The Office issues warnings for the eight hazards below. Hazards not listed, such as poor air quality or high pollen, are the subject of advice from other departments of the Network, to which the Office supplies its observations.
- Strong wind
- Gusts capable of damaging structures, bringing down trees or making travel and outdoor work unsafe. Assessed on the strongest gusts expected at exposed sites.
- Heavy rain and flooding
- Rainfall likely to flood roads, sites and low-lying ground, whether from prolonged rain or from short intense downpours. The Fenmoor lowlands and the Kilnbridge valley are the areas most often affected.
- Snow and ice
- Settling snow and the formation of ice on roads, paths and hard standings. Warnings distinguish between the uplands around Ridgeway Summit and the lower ground of the Network.
- Fog
- Visibility low enough to disrupt road travel and operations at the principal sites. Fog warnings state the period during which visibility is expected to be lowest.
- Thunderstorms
- Lightning, hail and sudden strong gusts. Thunderstorm warnings are often issued at short notice and are reviewed hourly while they are in force.
- Extreme heat
- Sustained high temperatures affecting health, outdoor work and the operation of equipment. Issued in consultation with the Health Department.
- Extreme cold
- Sustained low temperatures affecting health, water supplies and the operation of sites. Issued in consultation with the Health Department.
- Coastal storm surge
- Sea levels raised above predicted high water by wind and low pressure, affecting Southbank Terminal, Harbour Head and Saltmarsh. Issued with the coastal waters forecast.
How a warning is issued. Every warning follows the same steps, whatever the hazard and the level.
Step 1: A hazard is identified
The duty forecaster identifies from the model guidance, the observations and the radar that weather meeting the criteria for a warning is possible within the next forty-eight hours.
Step 2: The level is assessed
The forecaster assesses the likelihood of the weather and the impact it would have on the sites, services and citizens of the Network, and sets the level accordingly. A likely event of moderate impact and an unlikely event of severe impact may both be warned for at Level 2.
Step 3: The warning is drafted and checked
The warning states the hazard, the area, the period, the level, the action expected and the time of the next review. A second forecaster checks it against the criteria and the forecast in force.
Step 4: The warning is issued
The warning is published on this page and in the Newsroom, and sent by email to the registered contacts of member organisations, to registered citizens and to the Emergency Management Department. Warnings at Level 4 are issued jointly with that Department.
Step 5: The warning is reviewed
Every warning is reviewed at the stated time and whenever the situation changes. It is then extended, raised, lowered or cancelled, and the change is published and sent in the same way as the original warning.
Receiving warnings by email. The warning service is open from 6 September 2026 to member organisations and to citizens of the Network.
Step 1: Nominate your contacts
Member organisations write to the Office naming the people who are to receive warnings, with their email addresses and the sites they are responsible for. At least two contacts should be nominated so that warnings are received outside normal hours.
Step 2: Register as a citizen
Citizens of the Network may register by writing to the Office with their name, their email address and the site or area they wish to receive warnings for. Registration is confirmed by email.
Step 3: Receive and acknowledge warnings
Warnings are sent as soon as they are issued and again whenever they are changed. Contacts of member organisations are asked to acknowledge warnings at Level 3 and above so that the Office knows they have been received.
Step 4: Keep your details current
Write to the Office when a contact changes. Details are held only for the purpose of sending warnings and are removed when registration is withdrawn.
Requests to register, and enquiries about warnings, may be sent to contact@meteorology.gov.vin. For the observations against which warnings are judged, see Observations; for answers to common questions, see the frequently asked questions.