Forecasts for snow and ice following a sudden cold snap have prompted UK authorities to issue a special cold weather health alert.

Met Office warnings already in place for snow and ice in Northern Ireland, North West England and swathes of Scotland are due to be followed this weekend by further snow alerts for most of England and Wales.

The country is braced for three days of snow, while at the same time large areas will struggle with the after-effects of winter flooding.

While the government forecaster’s notices signal to the general public they should be prepared for disruption and possibly even to cancel any non-essential travel, the latest alerts by the UK Health Security Agency (UKHSA) warn officials there could be a surge in cold weather-related deaths.

Here, Yahoo News UK breaks down what the weather health alerts are, who they are for and what you need to do about them.

What does the latest cold-health alert say and where does it cover?

An amber cold-health alert has been put in place until at least 1pm on 8 January.

It says the current weather forecast weather is expected to significantly affect health and social care services, including:

• A rise in deaths, particularly among those aged 65 and over, or with health conditions

• A likely increase in demand for health services

• Temperatures inside places like hospitals, care homes, and clinics dropping below recommended levels and difficulty keeping indoor temperatures at the recommended 18C

• The possibility of other disruptions caused by power cuts and travel disruption

What is a weather health alert?

These are advisory notices issued by the UK Health Security Agency (UKHSA), for the NHS, local authorities and other relevant organisations, of expected severed weather.

This can range from a sudden weather event likely to shock key services, to longer duration events, such as a cold snap or heat wave, which can put excessive strain on the wider health of the population.

Who is responsible for issuing a weather health alert?

The weather alert system is run by the UK Health Security Agency (UKHSA).

It was previously the responsibility of the Met Office, but is now issued by UKHSA’s online alerting system, in partnership with the official forecaster.

Usually, the Met Office starts the process by assessing temperatures and any significant aspects of the upcoming weather forecast, such as snow and ice predictions.

If necessary, it can then pass this on to the UKHSA to consider whether to issue an alert.

Live details of active weather health alerts can be found here.

Who is a weather health alert for?

The alert system is mainly intended to notify organisations of oncoming weather that could affect or put greater strain on their services.

This could include:

• The health and social care sector, including hospitals and local authorities

• The ‘responder community’, such as police and paramedics

• Charities

• Government departments

When are weather health alerts issued and why?

Generally, cold-health alerts are issued between 1 November – 30 March, and heat-health alerts between 1 June – 30 September.

However, extraordinary alerts can also be issued outside of those periods.

Alerts are then issued based on whether forecast weather conditions could affect the health and wellbeing of the UK population.

What do the different alert colours mean and how do officials decide which to pick?

Weather health alerts come in four colours – red, amber, yellow and green.

Under the grading system, the level of severity is assigned based on the relative certainty of the forecast and the impact it is likely to have if it becomes a reality.

Red (emergency response) – Reserved for the most serious weather events with the highest degree of forecast certainty and likely to have the greatest impact. It indicates a “significant risk to life for even the healthy population”.

Amber (enhanced response) – Weather impacts are likely to be felt across the whole of the health service, with potential for the whole population to be at risk. Conditions may also affect other sectors and different departments and authorities may need to increase their level of communication and coordination.

Yellow (response) – Usually issued during periods of heat or cold that would be unlikely to impact most people, but could affect anyone considered particularly vulnerable. It may also be issued if the confidence in the weather forecast is low, but there could be a significant impact if it became a reality.

Green (preparedness) – Business as usual. No formal alert issued as the conditions are likely to have minimal impact on health. However, organisations should ensure they are ready to respond to a yellow, amber or red alert.

How are weather health alerts different to the Met Office’s own weather warning system?

Although similar, the Met Office’s warning system is distinct from the weather health alert system run with the UKHSA.

The National Severe Weather Warning Service (NSWWS) also uses a tiered system based on the likelihood and likely impact of a given weather event.

However, while the weather health alerts are mainly intended to inform the organisations expected to respond to severe weather, the NSWWS includes more information for the wider public.

For example, this could include advice be aware of the potential for travel disruption, or a warning of dangerous weather on its way which could be a risk to life if you fail to take adequate precautions.