Spring has sprung, but weather is iffy

Posted: March 20, 2013

The Winchester Star

Daffodils bloom in the springlike temperatures Tuesday on Marion Street in Winchester. (Photo by Jeff Taylor/The Winchester Star)
Alex Bowers, 9, and his mother, Tracy Johnston, walk their dog Guinness past blooming flowers on North Braddock Street Tuesday afternoon. (Photo by Scott Mason/The Winchester Star)

WINCHESTER — It’s spring.

But make sure you wear your warm coat and boots today ... it might snow tonight.

Meteorologist Howard Silverman of the National Weather Service said the first day of spring will be cooler than winter’s last day — when temperatures reached the mid-50s.

“The upper 40s is about the best you can expect,” he said.

That’s about five degrees colder than the 53-degree average for this time of year. And Thursday is expected to be even worse, with highs only in the upper 30s.

“You could see a few snow flurries,” tonight, he said of the Winchester area.

In fact, the outlook for the next seven days is for cooler-than-average temperatures and, on Sunday night and Monday morning, another storm system is likely to move through the Valley.

“We’re in a cold pattern,” Silverman said. “It doesn’t show any signs of breaking.”

The calendar date of spring is a question of time, not weather.

Today marks the beginning of the spring season, called the “vernal equinox.”

The words come from the Latin word vernalis, meaning spring, and equinox, meaning equal night.

Today at 7:02 a.m., the sun will cross the equator and usher in more daylight in the Northern Hemisphere. Day and night length are roughly equal today. The sun rises due east and sets due west.

That’s important to plants, said Woodrow “Woody” Bousquet, professor of environmental sciences and biology at Shenandoah University.

“Plants respond to day length, not temperature,” Bousquet said, to know when to begin to grow again. “That’s a good safety procedure.”

Virginia can throw some warm days into the mix in January and February. If plants allowed themselves to be fooled into starting to grow, a return of typical winter weather could kill them.

Plants contain hormones that are sensitive to light. And they must be exposed to enough light to trigger those hormones to begin to put out new stems or leaves or flowers.

By waiting for a trigger like the length of daylight, plants have a better chance of survival.

Yes, Bousquet said, we are going to see cold snaps ahead. But plants are prepared to weather short-term cold.

The water in plants has many substances dissolved in it, Bousquet said, which actually help them withstand cold tempertures.

“Even dissolving sugar in water lowers the freezing point,” Bousquet said.

In temperatures below 20 degrees, plants can suffer damage to tissues in the leaves and stems, which is why Florida citrus growers panic when a cold wave dips into the southern states.

But, Bousquet said, plants “invest in growth for the long term.”

If flowers and buds are killed by a cold snap, the plant will regroup, repair and wait until the next year to try to reproduce.

“We see things in human terms,” Bousquet said, like the loss of a crop or fewer roses to smell.

“Nature is in charge, and its priorities are not always ours.”

— Contact Val Van Meter at vvanmeter@winchesterstar.com