Governor Tom Wolf amended orders to include 10 counties moving to the yellow phase today, including Lehigh and Northampton. The order allows outdoor dining, but Mother Nature appears to have other plans.
The National Weather Service has issued a flash flood watch in effect from 2 p.m. through midnight. It’s our third straight day of an unsettled pattern that has largely spared the Lehigh Valley but wreaked havoc on Philadelphia and its suburbs. A derecho, a long-lived and expansive thunderstorm, produced widespread swaths of damage and killed four people on Wednesday.
According to the weather service, thunderstorms are expected to develop this afternoon in southeastern Pennsylvania into northern and central New Jersey. The strongest storms will be capable of producing locally heavy rainfall of 1.5 to 2.5 inches in as little as an hour.
Forecasters say storm motions will be slow, and may train over the same areas. As a result, instances of flash flooding are possible in the watch area, which covers portions of northern Delaware, northeast Maryland, New Jersey, and Pennsylvania.
In the ‘yellow’ phase, large gatherings of more than 25 people are still prohibited, a restriction that swells to no more than 250 people when a county enters the green phase. That means restaurants will have to get creative with outdoor seating arrangements, and it will become even more challenging with rain in the forecast.
Each of the area’s three major cities recently announced plans to enact street closures to help restaurants extend their footprints for outdoor dining. But you likely won’t see many patrons if storms roll through later today.
“We could see some showers and thunderstorms through the day on Friday, really anywhere,” said meteorologist Ed Vallee of Empire Weather, which provides local forecasts for The Morning Call.
The weather service forecasts using a probability of precipitation, or POP, defined as the likelihood of occurrence of measurable precipitation during a specified period of time at any given point in the forecast area.
NWS forecasters use categorical terms such as occasional, intermittent, or periods of to describe a precipitation event that has a high probability of occurrence (80%+), but is expected to be of an “on and off” nature. A chance in the 30-50% range means scattered showers, while 60-70% means numerous showers will likely occur. Anything higher (80, 90, and 100%) mean periods of rain can almost certainly be expected.
Today’s high temperatures will likely favor the 80s as warm, moist air hangs around.
Folks looking to alleviate their cabin fever will see a better forecast for the remainder of the weekend. It should be mostly sunny by Saturday afternoon with highs in the low 80s. Forecasters agree Sunday will be a near-perfect day, with clear skies and a high of 76 degrees.
All eyes will be on the remnants of tropical storm Cristobal next week. The weather service said what’s left of the storm will be absorbed into a low pressure system targeting our area. There is the potential for heavy rain with a stalled pattern later next week, though many of the details are uncertain at this time.
