Frost advisories are posted as Philly has its chilliest spell in six months
More frost advisories are possible through the weekend. Meanwhile, the dry spell goes on.
Frost advisories are up for Friday morning for areas just outside Philadelphia on both sides of the Delaware River as the region is about to experience its chilliest spell in more than six months.
While the urban hotplate areas of Philly and Delaware County were not included in the National Weather Service advisory zones, cooler areas of the city and Delco could see some patchy white.
“It is certainly possible,” said Zachary Cooper, a meteorologist at the agency’s Mount Holly office.
Conditions conducive to frost — relatively clear skies, temperatures in the 30s, and light winds — may whiten the pumpkins in the region through the weekend.
As per standard procedure, the weather service will be issuing frost advisories until the end of the growing season, defined as the first time temperatures reach 32 degrees or lower in a given area.
It won’t be freezing, just frosty
Philly’s first freezing reading typically doesn’t occur until mid-November, but frost can form with temperatures above 32.
The air temperatures are measured about six feet off the ground, but they can be several degrees lower on the ground and on cooler surfaces.
When winds are calm, they keep the air from mixing, and that allows thin layers of colder air to develop at ground level.
The winds won’t be completely calm Friday morning, but “they should be light enough for favorable” frost conditions, the weather service said.
The dry spell in the Philly region continues
Temperatures should be several degrees below normal into next week, with highs mostly in the 50s and lows 35 to 40 degrees, the weather service says.
Notably absent from the extended outlook is precipitation. Officially, at Philadelphia International Airport, only 0.81 inches of rain have fallen this month. That’s less than a third of normal.
Most of the region is in “moderate drought,” and remaining areas are “abnormally dry,” according to the U.S. Drought Monitor’s Thursday update.
That could change the middle of next week, as computer models have been hinting at an active pattern.
However, this should be a splendid weekend to get out and enjoy the burgeoning foliage show.