PEORIA, Ill. (WMBD) — Monday (as of 4:24 p.m.) is the first “official” day of Spring. What does that really mean? Not much. It is just a benchmark.
“Meteorological” Spring started March 1. Meteorologists basically split the year into quarters for the sake of statistics.
“Astronomical” Spring is tied to the Earth’s tilt (23.5°). Monday is also known as the “Vernal Equinox. The vernal equinox marks the turning point when daylight begins to win out over darkness.
I usually refer to the equinox as the day when light and darkness are equal. Close, but not true. Long explanation, but because the Earth has an atmosphere, other things factor in.
After the vernal equinox, the direct rays of the Sun migrate north of the Equator (with hours of daylight steadily growing longer) until they finally arrive at the Tropic of the Cancer (latitude 23.5 degrees north) around June 21.
Spring is the most active weather season of the year, certainly for Central Illinois.
Spring is notorious for producing a broad range of extreme weather, including major snowstorms, severe thunderstorms, flooding, big temperature changes, and high winds.
The big weather fluctuations occur this time of year because of warmer air trying to push farther north and the winter cold pushing south out of Canada. They (fronts) end up clashing somewhere.
Spring has a history of major winter storms
Many parts of the country can still see winter storms in spring, especially early in the season. The Rockies deal with snowstorms and blizzards into May.
In fact, March and April are actually the snowiest months of the year in the Rockies and High Plains. The last measurable snow in many cities across the nation’s northern tier actually comes in April.
Peoria has had snow Tornado outbreaks, which are probably the weather event most often associated with spring. Tornado activity in the Lower 48 increases in March before peaking in April, May, and June.
March averages the fewest tornadoes in spring, with 87 per year. That average increases to 197 in April and 277 in May, based on the period from 2002 to 2021.
The area of highest tornado risk in spring shifts from the Deep South in March toward the Plains and Midwest from April into May.
Flash flooding threat is greater in Spring as thunderstorms become more numerous. Thunderstorms can produce rainfall rates of more than an inch per hour.
Major flash flooding can occur if that heavy rain persists for several hours at a time in a particular area. March is our windiest month of the year.
The wind is driven by differences in temperature and air pressure over small distances. In March, when winter is transitioning to spring, cold air masses and warm air masses are frequently in close proximity.
March tends to be windy because it is a period of transition. The sun is higher in the sky and the earth warms up in places, creating pockets of relatively hot air.
Illinois is not on the list of the ten windiest states. The ones that are, typically have more flat, open areas. Less friction to block the winds.
*Meteorologist Jeff Andrews
