Forecasts

The Meteorological Office of the Velocity Interoperability Network issues forecasts for the whole Network, for its six principal sites and for its coastal waters. The first Network forecast was issued at 05:30 on 6 September 2026 from the forecasting centre at Central Exchange, which is staffed at all hours. Forecasts are published on this site and sent by email to the registered contacts of member organisations.

Every forecast states the period it covers, the time it was issued and the time of the next issue. Where the weather expected is hazardous, the forecast refers to the warning in force; a forecast never replaces a warning, and a warning never replaces a forecast.

The forecast schedule. Forecasts are issued at the fixed times below so that member organisations can plan their operations around them.

Site forecasts are issued for Central Exchange, Northgate Relay, Southbank Terminal, Eastfield Campus, Westbrook Distribution Site and Meridian Court. The coastal waters forecast gives wind, sea state, visibility and the height and timing of high water for the coast between Harbour Head and Saltmarsh. Forecasts for aerodromes and for particular operations will be provided to member organisations under arrangements to be announced in the Newsroom.

How a forecast is made. A forecast is the product of observation, analysis, calculation and judgement, in that order. The steps below are followed for every forecast the Office issues.

1. 1

   Step 1: Observations are gathered

   Every hour the twelve stations of the observing network report temperature, humidity, pressure, wind, rainfall, visibility and cloud to the forecasting centre at Central Exchange. The two weather radars scan the Network every five minutes, and a sounding balloon released at Central Exchange at 00:00 and 12:00 measures the atmosphere to a height of about thirty kilometres.

2. 2

   Step 2: The atmosphere is analysed

   The duty forecaster draws the synoptic analysis: the pressure pattern, the position of fronts and the air masses over the Network. The analysis is compared with the previous one so that the movement of weather systems can be followed.

3. 3

   Step 3: The numerical model is run

   The Office's numerical prediction model runs at 00:00, 06:00, 12:00 and 18:00 on the latest observations and produces guidance for the following seven days. The model is a calculation, not a forecast; its output is the starting point for the forecaster, not the end of the process.

4. 4

   Step 4: The forecast is prepared

   The duty forecaster weighs the model guidance against the analysis, the radar and the local knowledge of the Network's sites, and writes the forecast in plain language: what will happen, where, when and with what confidence.

5. 5

   Step 5: The forecast is checked and issued

   A second forecaster checks every forecast for consistency with the observations and with any warning in force. Forecasts are issued at the fixed times in the schedule, so that member organisations can plan around them, and are amended between issues only when the situation changes materially.

6. 6

   Step 6: The forecast is verified

   After the period of every forecast has passed, the forecast is compared with the weather that was recorded. The Office will publish verification figures monthly from October 2026, so that the accuracy of its forecasts can be seen by everyone who relies on them.

The observing network. No forecast is better than the observations it rests on. The figures below describe the network from which the Office's forecasts are made; the register of stations is set out on the Stations page.

12

Observing stations reporting hourly to the forecasting centre

2

Weather radars, at Harbour Head and Ridgeway Summit, scanning every five minutes

2

Upper-air soundings each day from Central Exchange, at 00:00 and 12:00

288

Surface observations recorded across the Network every day

Confidence and limits. The Network forecast for the next twenty-four hours is expected to be right in its essentials on the great majority of days. Confidence falls with time: the five-day outlook describes the general character of the weather rather than the detail of any hour, and the monthly outlook describes only whether the period is likely to be warmer, colder, wetter or drier than usual. Where the forecaster's confidence is low, the forecast says so.

Enquiries about forecasts may be sent to contact@meteorology.gov.vin. For the observations on which forecasts are based, see Observations; for the records of past weather, see Climate Records; for answers to common questions, see the frequently asked questions.