The forecast for the huge storm that hit Delaware today has been evolving over the last few days, and one of the latest updates is the possibility of thundersnow.
Thundersnow is a rare phenomenon, said Trent Davis, a meteorologist with the National Weather Service in Mount Holly, New Jersey. And it’s even more rarely witnessed.
“The lightning tends to be intracloud,” rather than hitting the ground, he explained. “And the snow muffles the sound and makes the lightning hard to see.”
That said, videographers have captured it, as this CNN compilation shows.
“The ingredients for thundersnow are similar to a thunderstorm that forms in the summertime: warm, moist air rising toward a colder air mass above, creating instability,” ABC reported. “Although the lower air mass has to be warmer than the air above, the entire column has to be cold enough for snow to fall and reach the ground. This can be tricky during the wintertime, which is why thundersnow doesn’t happen often.”
There’s still uncertainty on the snow accumulation from today’s nor’easter. “Snow amounts will be highly dependent on the dominant precipitation type,” the weather service said in explaining a “sharp gradient” of predictions of 0 to 8 inches in New Castle County.
A winter weather advisory is in effect for northern Delaware until 10 a.m. Thursday, with a coastal flood advisory in effect for downstate Delaware until 3 p.m. Thursday.
A gale warning is in effect through Thursday morning on the Delaware River and upper Delaware Bay, with a storm warning in effect on the lower Delaware Bay and Atlantic Ocean.
A snowstorm that struck the mid-Atlantic on Christmas Eve of 1966 had so much lightning and thunder that weather historian David Ludlum dubbed it the “Donner and Blitzen Snowstorm,” the Farmers’ Almanac wrote. Donner and Blitzen are two of Santa’s reindeer, and they’re also the German words for thunder and lightning.