Mid-May frost a chilling possibility
Last month a premature heat wave forced the locals to crank up their air-conditioners. Tomorrow morning, some folks may need ice scrapers.
Last month a premature heat wave forced the locals to crank up their air-conditioners. Tomorrow morning, some folks may need ice scrapers.
Overnight, the atmosphere will become about as chilly as it gets around here this time of year. The National Weather Services warns that scattered frost is possible in the normally cooler Pennsylvania suburbs and in the New Jersey Pine Barrens.
The winds will be light and the skies clear - near perfect conditions for daytime heat to radiate into space after dark.
The Pine Barrens are particularly susceptible to frost, said Raymond Kruzdlo, meteorologist with the National Weather Service office in Mount Holly.
"They radiate very well," he said, thanks to lack of heat-absorbing paving and their sandy surfaces that reflect back some of the sun's heat in daytime.
In the Pennsylvania suburbs, like the terrain, the frost siutation is a bit more complicated.
Whereas in winter, the higher elevations tend to be cooler, on wind-less nights, cold air often collects in low-lying area. "The colder air that forms rolls down the terrain," Kruzdlo said.
The official forecast calls for a low of 44 at Philadelphia International Airport. That's just 3 degrees shy of the all-time record, 41, set in 1882, one of the longest-standing records in the books.
Frost is possible even when temperatures are above freezing because the ground and other surfaces often are colder than the surrounding air.
But outside of newly planted annuals, any frost is unlikely to pose a signficant threat to the region's plant life, said Todd Greenberg, chief gardener at Bartram's Garden, in Philadelphia.
