The National Weather Service issued an updated coastal flood warning at 10:26 a.m. Friday, effective between 2 p.m. and 7 p.m. Friday for Lower Bucks, Delaware and Philadelphia counties.

“Flooding up to half a foot above ground level is expected in low-lying areas near the coast and tidal waterways,” the weather service explains. “Further tidal flooding is possible with high tide cycles on Saturday and Sunday.”

“Minor flooding will result in widespread street flooding in coastal and bay communities and along inland tidal waterways,” the weather service explains. “If you must travel, allow extra time as some roads may be closed. Do not drive around barricades or through waters of unknown depth. Take necessary steps to protect property at risk of flooding.”

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. If you are in a flood-prone area, get to higher ground immediately. A flash flood is a sudden, severe flood that can develop from minutes to hours. It is even possible to experience flash flooding in areas where there is no immediate rainfall.

• Flood warning: take action!

A flood warning is issued when flooding is imminent or occurring.

• 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.

Safe behaviour during floods: Recommendations from the weather service

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 where sockets or cables are under water. This way you can avoid electrical accidents.

For safety reasons, evacuate immediately:

If you notice sparks or hear buzzing, crackling, popping or banging noises, evacuate immediately. Do not enter water that may be live.

Stay away from floods:

Never attempt to walk through flood water. Even 15 cm of fast-flowing water can sweep you off your feet with full force.

Seek higher ground if you are trapped:

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

During heavy rain, the risk of flooding is increased, especially in low-lying and flood-prone areas. Always remember to never drive through water on the road, no matter how shallow it appears. According to the weather service, as little as 30 cm of fast-moving water can sweep away most vehicles. Your safety is paramount, by staying informed and prepared.

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