A powerful storm system out West is moving its way into our area, bringing a threat of severe and potentially dangerous storms. Massive thunderstorms swept through the Midwest on Wednesday. Meteorologists warn that the line of storms could launch a weather event called a derecho, which is a straight-line wind storm spanning at least 240 miles.
The entire state of Pennsylvania is under a flood watch overnight and through the day Thursday. Weather service officials say the greatest risk of flooding is in the northern portion of the state while the worst thunderstorms are expected in southern areas. Officials say a standby worker was added at the emergency operations center in Harrisburg and officials had ensured two National Guard helicopters were ready if needed for water rescues.
Storms are also now forming in Delaware and parts of extreme South Jersey.
The first line of storms is expected to arrive in Central Pennsylvania around 4 a.m. Periods of rain will begin to fall around 8 a.m. though there will be periods of dryness as well as a risk for isolated thunderstorms. NBC10 Meteorologist Bill Henley says to expect heavy rain during the morning commute, with conditions worsening by the afternoon.
By 12 p.m., strong thunderstorms will hit the area and continue throughout the rest of the day with its peak hitting at 5 p.m. The storms could be potentially severe with damaging winds.
8 a.m. - Showers/Possible Thunderstorm
12 p.m. - Strong Thunderstorms
5 p.m. - Strong Thunderstorms (Peak)
This graphic shows the elevated risk of severe weather in Southeastern Pennsylvania, South Jersey and Delaware.
The area in red is most likely to experience strong thunderstorms in the afternoon, with a possibility of isolated tornadoes, says Henley. There is also a threat of powerful winds and hail.
There's also a Flood Watch in effect for our entire area, with a Flood warning in Burlington County.
Between 1-3 inches of rain is expected, Henley says. The wet weather is expected to linger through the evening before it begins to taper off.
On Monday, a tornado tore through a neighborhood in Newark, Del. The National Weather Service says the funnel cloud was 150 yards wide and left four-tenths of a mile path of destruction.
Minor flooding was also reported along the east branch of the Brandywine Creek below Downingtown in Chester County.
"It's going to be a dramatic change from sunshine today to the threat of severe weather tomorrow," says Henley, who reminds people to bring in lawn furniture or make any other preparations today before the stormy weather begins.