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Thursday 9 February 2023 Dublin: 3°C
Sasko Lazarov The coast in Dublin is hit by rough waves as Storm Barra takes place
# Weather Warning
How does Met Éireann decide on weather warnings?
The forecaster will usually refrain from issuing warnings more than 60-hours in advance

THE IMPACT OF Storm Barra across the country is being felt today, as counties along the coasts are battered with high winds and rain.

Multiple weather warnings were issued by Met Éireann in recent days, with the first alert being raised on Sunday morning by the forecaster as the country was given a nationwide Status Yellow wind warning.

These warnings were soon upgraded to Orange level for some counties on the South coast, before Cork and Kerry were given Status Red status yesterday afternoon.

With Storm Barra set to continue to impact the country throughout today and tomorrow, Met Éireann will continue to issue updates on any changes to weather warnings – but how does the forecaster actually decide on what warnings to use?

According to Met Éireann, the forecaster will usually refrain from issuing weather warnings more than 60-hours in advance of the weather event occurring.

When it’s within 60 hours, the main set of warnings are issued by the duty forecaster at Met Éireann between 10am and midday. These warnings will then be regularly updated as new information becomes available.

However, the forecaster will issue weather advisories up to a week in advance, which acts as an early warning for people for potential hazardous weather conditions. These advisories are also used when multiple weather conditions are expected to act together to cause a significant hazard.

When asked about Met Éireann’s confidence in predicting weather several days in advance on The Explainer last year, Head of Forecasting Evelyn Cusack said that it depends on the atmosphere.

“It actually depends on the weather! Sometimes the atmosphere is in a more predictable state than others,” said Cusack.

“We only ever issue warnings about 48 hours to 60 hours ahead, we don’t issue warnings further than that because things can vary too much.

“We can give advisories 10 days ahead based on the European model, but even within 48 hours there is still a degree of uncertainty.”

The European model, which is the European Centre for Medium-Range Weather Forecasts (ECMWF), is used for longer forecasting by Met Éireann, as it covers the entire globe.

Cusack said that the forecaster is careful when issuing warnings, as they want to ensure that they are only issuing them when they are confident that certain weather will actually impact Ireland.

“Ireland is very small and if you look at the size of the Atlantic, weather systems come across 3000 miles and we’re only 200 miles wide or long or whatever, so if they miss us by 50 miles, it doesn’t seem a lot if you’re a mathematician but in terms of for people on the ground, us the citizen, it can mean a huge amount,” said Cusack.

“It’s the difference between a warning and not a warning and of course, we don’t want to cry wolf.”

Warning types

There are three types of weather warnings that can be issued in Ireland by Met Éireann: Status Yellow, Status Orange and Status Red.

These individual warning types are all associated with different strengths of weather, with Status Yellow being the mildest and Status Red being the most extreme.

Status Yellow is also the most commonly issued weather warning, with Met Éireann describing it as “not unusual weather”. It is not a threat to the general population, but can cause issues on a localised level.

Status Orange is a step up and is described as being “infrequent and dangerous weather conditions which may pose a threat to life and property”.

Status Red is the most dangerous and most extreme weather warning that Met Éireann can issue, with the weather conditions being caused by an “intense meteorological phenomena”. For Status Red warnings, people are asked to shelter in place if possible.

Specific conditions for these warning types are described by Met Éireann, with Status Yellow wind warnings being issued for mean windspeeds of between 50 and 65km/h and mean gusts of between 90 and 110km/h.

Meanwhile, a Status Red wind warning would be issued for widespread wind speeds in excess of 80km/h and widespread gusts in excess of 130km/h.

However, Met Éireann does not strictly decide the weather warnings off these specific metrics alone, but on the potential impacts that the weather may have.

“When we’re issuing warnings, we try to take into account impacts,” said Cusack.

With the warnings, personal safety advice has been issued by organisations like the Gardaí, Coast Guard and Road Safety Authority.

They have encouraged people to stay away from coastal areas while warnings are in place, and that road users should be aware of any hazardous traveling conditions before setting off on a journey.

Motorists are being warned to be careful of fallen trees, electricity poles and other debris. Warnings have also been issued for the public to stay clear of electricity wires, and to call ESB Networks on 1800 372 999 if they spot any fallen wires.

In areas where Status Red warnings are in place, people are being asked to shelter in place for the duration of the warning.

Due to the warning, schools in all areas impacted by either a Status Red or Status Orange weather warning have been closed. The closure was announced by the Department of Education yesterday evening.

According to the Department, schools in Status Orange counties were closed due to the “strong possibility that the status of parts of these counties currently in status orange are likely to change and escalate to status red”.

Earlier this morning, the government said that a decision on whether or not schools will reopen tomorrow will be made later this evening.

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