A potent weather system is expected to bring severe thunderstorms to central Pennsylvania today, followed by an intense heat wave that could produce dangerous temperatures through next week.

Severe thunderstorms are forecast for Thursday afternoon and evening, particularly across the southeastern half of central Pennsylvania. They could bring strong wind gusts and isolated flash flooding.

The National Weather Service in State College has issued a severe thunderstorm watch for the eastern third of the state, effective until 9 p.m. Thursday.

The watch includes Dauphin, Cumberland, Perry, York, Adams, Lancaster and Lebanon counties.

Storms are expected to develop by late afternoon. The Weather Channel says the Harrisburg area is most likely to see storms around 3 p.m.

A significant heat wave will rapidly develop this weekend, with temperatures climbing into the 90s by Sunday and potentially reaching extreme levels early next week.

Summer begins at 10:42 p.m. Friday, coinciding with the year’s longest day with 15 hours and 6 minutes of daylight. Friday will offer a brief respite with slightly lower humidity and temperatures in the 80s, before the heat intensifies over the weekend.

Current weather radar

Generative AI was used to produce an initial draft of this story, which was reviewed and edited by PennLive.com staff.

A report was issued from the National Weather Service on Wednesday at 6:51 p.m. for strong thunderstorms until 9 p.m. for Northern Clinton and Northern Centre as well as Potter, Cameron, Clearfield, Cambria and Somerset counties.

Shielding yourself from approaching lightning: Expert safety guidelines

Lightning strikes the United States approximately 25 million times each year, with the bulk of these electrical discharges occurring during the summer months. Tragically, lightning claims the lives of about 20 individuals annually, as reported by the weather service. The risk of lightning-related incidents escalates as thunderstorms draw near, reaching its peak when the storm directly looms overhead. However, it gradually recedes as the tempest moves away.

To ensure your safety during a thunderstorm, consider the following recommendations:

Lightning safety plan:

• When venturing outdoors, it’s crucial to have a lightning safety plan in place.
• Monitor the sky for threatening signs and listen for the sound of thunder. If thunder is audible, it’s an indication that lightning is nearby.
• Seek shelter promptly in a safe location, preferably indoors.

Indoors safety measures:

• Once you’re indoors, avoid using corded phones, electrical devices, plumbing fixtures, and stay away from windows and doors.
• Lightning can follow conductive pathways, and these precautions reduce the risk of electrical surges.

Wait for the all-clear:

• After the last lightning strike or thunderclap, wait at least 30 minutes before resuming outdoor activities.
• Lightning can strike even when a storm has seemingly passed, so exercise caution.

When indoor shelter isn’t available:

If you find yourself outdoors without access to indoor shelter during a thunderstorm, take these steps to maximize your safety:

• Avoid open fields, hilltops, or ridge crests, as they expose you to greater lightning risk.
• Steer clear of tall, isolated trees and other prominent objects. In wooded areas, stay close to lower stands of trees.
• If you’re in a group, ensure that individuals are spaced out to prevent lightning current from transferring between people.
• Camping in an open setting during a thunderstorm is strongly discouraged. If you have no alternative, set up camp in a valley, ravine, or other low-lying areas. It’s crucial to note that a tent provides no protection against lightning.
• Do not approach water bodies, wet objects, or metal items. Although water and metal do not attract lightning, they conduct electricity effectively and can pose significant risks.

In summary, when facing the threat of lightning, preparedness and vigilance are your best allies. By following these guidelines, you can significantly reduce the likelihood of lightning-related incidents and prioritize your safety.

Navigating heavy rain: Essential safety measures for wet roads

When heavy rain pours, the risk of flooding and treacherous roads rises. Here’s your guide from the weather service to staying safe during downpours:

Beware of rapid water flow:

During heavy rain, avoid parking or walking near culverts or drainage ditches, where swift-moving water can pose a serious risk.

Maintain safe driving distances:

Adhere to the two-second rule for maintaining a safe following distance behind the vehicle in front of you. In heavy rain, allow an additional two seconds of distance to compensate for reduced traction and braking effectiveness.

Slow down and drive with care:

If it is raining and the roads are wet, slow down. Take your foot off the accelerator and let your speed drop gradually. Never use the brakes suddenly because this may cause the car to skid.

Choose your lane wisely:

Stay toward the middle lanes – water tends to pool in the outside lanes.

Visibility matters:

Enhance your visibility in heavy rain by turning on your headlights. Watch out for vehicles in blind spots, as rain-smeared windows can obscure them.

Watch out for slippery roads:

Be extra careful during the first half hour after rain begins. Grime and oil on the road surface mix with water to make the road slippery.

Keep a safe distance from large vehicles:

Large trucks and buses can reduce your visibility with tire spray. Avoid tailgating and pass them swiftly and safely.

Mind your windshield wipers:

Overloaded wiper blades can hinder visibility. If rain severely limits your sight, pull over and wait for conditions to improve. Seek refuge at rest areas or protected spots.

When stopping by the roadside is your only option, position your vehicle as far off the road as possible, ideally beyond guardrails. Keep your headlights on and activate emergency flashers to alert other drivers of your position.

In the face of heavy rain, these precautions can make a significant difference in ensuring your safety on the road. Remember to stay informed about weather conditions and heed guidance from local authorities for a secure journey.

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