At 3:08 a.m. Friday, the National Weather Service issued a flood warning that is in effect from 11 p.m. to 5 a.m. Saturday for Essex, Plymouth, Barnstable and Nantucket counties.

The weather service states: “If you must travel, allow extra time as some roads may be closed. Do not drive around barriers or through waters of unknown depth. Take necessary steps to protect property at risk of flooding. Inexperienced swimmers should not enter the water due to dangerous surf conditions.”

Understanding the differences between advisories, observations and warnings

• Flash flood warning: take action!

A flash flood warning is issued when a flash flood is imminent or is already occurring. In areas at risk of flooding, it is important to get to higher ground immediately. A flash flood is a sudden and severe flood that can develop within minutes to hours and can occur even in areas where there is currently no rainfall.

• Flood warning: take action!

A flood warning is issued when flooding is imminent or already underway.

• Flood warning: Please note:

A Flood Warning is issued when flooding is not expected to reach a level of severity that would warrant a warning. However, such a warning may cause significant inconvenience and, if ignored, may result in situations threatening life and/or property.

• Flood warning: Be prepared:

A flood warning is issued when conditions are favourable for flooding. It does not guarantee that flooding will occur, but indicates that the possibility exists.

Be prepared for flooding: Expert tips from the weather service for your safety

In flood-prone regions or when camping in low-lying areas, understanding and following the weather service’s flood safety guidelines can be life-saving:

Find higher ground:

If you are in a flood-prone area or camping in a low-lying area, the first step is to move to higher ground.

Follow the evacuation instructions:

If local authorities issue an evacuation order, obey it immediately. Secure your home by locking it before leaving.

Disconnect utilities and equipment:

If time permits, unplug your utilities and appliances. This will reduce the risk of electrical hazards during flooding.

Avoid basements and flooded areas:

Avoid basements or rooms in contact with water where there are electrical outlets or cables. Preventing electrical accidents is crucial.

Fast evacuation for your safety:

If you notice sparks or hear buzzing, crackling, popping or banging noises, leave the area immediately. Avoid water that may be live.

Stay away from floods:

Never attempt to walk through flood water, even if it appears shallow. Even 6 inches of fast-flowing water can sweep you off your feet with full force.

If you are trapped, seek higher ground:

If you are trapped in running water, go to the highest possible point and dial 911 to contact emergency services.

Heavy rain increases the risk of flooding, especially in low-lying and flood-prone areas. Remember this important advice: never attempt to drive through water on the road, even if it doesn’t appear deep. According to the weather service, as little as 30 cm of fast-moving water can sweep away most vehicles. Stay safe by being prepared and informed.

Advance Local Weather Alerts is a service from United Robots that uses machine learning to compile the latest data from the National Weather Service.