People with oak trees in their yards may be getting the impression that there is a little extra crunch under their feet this year.
The reason for a bumper crop of acorns, also known as a "mast year" may have a tie to weather.
Dr. Marc Abrams, a professor of forestry at Penn State, said mast years occur when nut-producing trees such as a oaks "produce an overabundance of nuts in a particular year, maybe five or 10 times more than an average year."
However, Abrams described the mast year phenomenon as "one of the amazing mysteries in nature that we still do not have a handle on."
Mast years happen irregularly, which Abrams said can make it challenging for scientists to understand what causes a mast year.
According to Abrams, a mast year can occur twice in a row or they might be several years in between.
"There's no way to predict it," he said.
While there is some speculation that mast years have a weather connection, Abrams said that there is no definitive research in the area.
"There might be, sometimes, a weather connection," he said.
Determining when a mast year occurs and what causes it is further complicated by the fact that most of the acorns or nuts are formed in a two-year cycle. This suggests that if there is a weather connection, it could apply to the year before an actual bumper crop.
Mast events also happen over a vast geographic area, which will most likely see a variety of weather conditions within its boundaries. -- as much as hundreds, thousands of miles. And Abrams said within that large a region, the weather can vary significantly.
Beyond weather, Abrams said, "There is a chemical signal hypothesis, that maybe the trees are giving off some sort of chemical cue or signal that cues them to have an abundance."
But he said, "There's other things that could cue trees in a region. One would be a weather condition that they're all tuned into."
Following a dip in temperature during the middle of the week, summerlike warmth will rebound across much of the Northeast by this weekend.
An outbreak of severe weather is targeting areas from Texas to Nebraska Wednesday evening.
Daily episodes of severe thunderstorms and flooding downpours will impact the Plains this week, possibly lingering into the weekend.
While a few showers will pass east of the Bay Area, seasonable weather and sunshine will hold in place through the weekend.
The central and southern Plains will continue to be pummeled by strong storms for the next several days, but the most potent severe weather threat is likely to be during the Mother's Day weekend.
Wind, seas and surf will build in advance of what is likely to become the first tropical system of 2015 along the southeastern Atlantic coast of the United States late this week.
White Mountain 2, CA (1964)
-15 degrees; U.S. record for May (lower 48 states).
A few tornadoes touched down in Kansas and Iowa, killing two people. Thunderstorms in eastern Kansas produced baseball-sized hail at Scranton and golf ball-sized hail at Silverdale.
North Carolina Mountains (1992)
Freak snowstorm buried the region. Mt. Pisgah picked up 57"; Mt. Mitchell got 50-60".