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Weather Almanac

Weather Almanac for February 1998

Celebrating Groundhog Day

Who knows what mysteries lurk in the depths of the ever changing weather? The Shadow knows!

And not just any shadow, but the shadow a small, furry member of the rodent family commonly known in North America as the groundhog. Or at least that is what "weather" folklore tells us. Here in North America, there is only one date in the Meteorological Calendar known to most of the population: February 2nd, Groundhog Day. Ask most people what the date of the spring equinox or the winter solstice is, and they will likely get the right month but not the day. Ask anyone what day is Groundhog Day and most will say: "February 2nd."

Now I do not believe the 'Hog has any special prognostic powers when it comes to weather forecasting. But I think the annual celebration of Groundhog Day is loads of fun. In fact, I think it should be a holiday -- we really don't have a good one for February. The date has roots similar to Halloween and, although I hate to say it, all sorts of commercial possibilities.

Such a celebration gives us the chance to promote weather and climate and have some fun, get our minds off the disasters and crippling storms and cold of winter. In December we all "dream of a white Christmas," but now as February begins most of us, weary from the fight against ice and snow and cold, start dreaming of spring.

Hog Roots

How did this groundhog thing get started anyway? According to my sources -- no, not the squirrels -- the Emperor Justinian I in 542 AD declared February 2 the Feast of the Purification of the Virgin. In medieval Europe this date became Candlemas Day, the date when the candles to be used for the remainder of the year are blessed.

The date is the approximate middle of winter (more on that later). Rural folk took this day as a point to turn their backs on winter and look forward to the coming spring chores on the farm. They derived a variety of signs to watch for at that time, but most have a common thread: sunny foretells continued cold; cloudy, the quick end to winter. In Germany, shepherds would rather a wolf entered their flock than see a sunny Candlemas. French farmers believed a sunny Candlemas meant another winter surge was on the way. In Spain, a wet day indicated the coldest weather was behind.

Folk legends have long endowed certain animals the ability to foresee the coming weather. The hedgehog, bear and the badger in Europe stir from their hibernation around early February and folks believed that they poked their noses out of their burrows or dens to see if it was time to come out or time to roll over for another month. (Western European winters, like those along the North American west coast are generally milder and shorter than those along the North American east coast.) North America has no hedgehogs so European settlers endowed the New World groundhog or woodchuck with this predictive insight.

European religious lore also gave special weather foretelling powers to certain holy days, most celebrating a saint. Like the weather on St. Swithin's Day or St Joseph's Day, weather on Candlemas Day was taken as a harbinger of weather to come. One saying states: If Candlemas Day be fair and bright;winter will have another flight, but if Candlemas Day brings cloud and rain, winter is gone and won't come again. Sound familiar?

So Protestant North American settlers combined the sayings of folklore surrounding a Catholic holy day and the believed forecasting prowess of animals, notably a sleepy rodent, and produced Groundhog Day. The day caught the fancy of the modern media, in the same vein as the Old Farmer's Almanac and astrology have. Every year it gives them something light to base a feature story on. The most famous groundhog is Punxsutawney Phil in Punxsutawney, Pennsylvania where the local chamber of commerce has made their groundhog the prime 'hog for the U.S. Canada has Wiarton Willie, an albino groundhog who resides northwest of Toronto, Ontario, outside the community of Wiarton. Willie often sees the weather picture from a different perspective than Phil, several hundred kilometres to the north.

Is There Any Truth To The Legend?

Okay, let's get down to the basics here. Is there any validity to the groundhog or Candlemas lore as far as weather forecasting goes? What Phil or Willie or one of their cousins is looking for, according to the legends is their shadow. If a distinct shadow appears, winter will continue for six more weeks. (In parts of Canada, that would be an early spring!) If no shadow is seen, winter has broken and spring is just around the corner.

Thus, we are looking for weather dominated by either sun (shadow) or heavy cloud (no shadow). A sunny winter day at these latitudes indicates a weather situation likely dominated by a cold high pressure system. Such conditions may last for another day or two or three. A winter day with grey skies and weak sun giving no shadow usually indicates that a frontal system dominates the weather, generally the influx of warmer, moist air from the Gulf of Mexico. (This system will likely be followed by a surge of cold arctic air within a few days, however.)

If we used the groundhog to forecast the weather for only the next few days, it would probably be right a bit better than half the time for the following day and decreasingly likely to be correct as the forecast is extended to additional days.. Meteorologists call such short-term forecasts persistence forecasts. That is, by forecasting that tomorrow's weather will be similar to today's, we are likely to be right more often than not, generally around 60 percent of the time at mid-latitudes. (In the tropics where weather doesn't vary much, a persistence forecast can be quite accurate. In areas along the polar front where storm waves rule and conditions change rapidly, it can be very unreliable.) So Willie and Phil seeing or not seeing their shadow can give a fair short-term weather forecast. Of course, a stick can do the same job, but sticks are not cute, fat, furry animals.

As for longer term -- six weeks or so -- forecasts, Phil, Willie and the boys (sorry, female groundhogs emerge from their hibernating dens much later in the season than the males) like all other animals are terrible long-range weather forecasters. Although they can get lucky and be right once in awhile -- even a stopped clock is right twice a day -- there are no reliable studies that indicate any animal has special abilities to foresee weather conditions. In fact, most observational evidence suggests quite the opposite. For example, migrating birds are often caught arriving in an area too early to avoid hazardous cold-season weather conditions, and die as a result.

What Then Is Special About February 2nd?

Before I close, I have one more comment on the significance of February 2nd. The date is the approximate midpoint between the winter solstice and the spring equinox. The way we define seasons based on astronomical positions of the sun, the date is thus mid-Winter. From a weather or climatic point of view, the date is not likely to be the midpoint of the cold season in the Northern Hemisphere away from the tropics, based upon either temperature or likelihood of frozen precipitation.

The date does have significance (in the Northern Hemisphere) for one important influence on weather: solar energy input. I call the date the start of Solar Spring because the three months with the lowest daily amount of solar energy received (under clear skies) has now ended, and for the next three months, the length of the day will increase quite rapidly.

You see, if you were to plot the noon-time position of the sun in the Northern Hemisphere sky or the day length for each day of the year, you would see a sine wave (see diagram) with its peak at the summer solstice around the 20th of June and its minimum at the winter solstice just before Christmas.



Day Length and Sun Energy Over Course of Year

Now, if we assume a solar year with four equal seasons and define winter as the 91-day period with minimal clear sky solar intensity or the shortest day lengths and summer as the season with maximum solar intensity or longest days, we have the following seasons. Solar Winter begins in early November and lasts until the first of February with midpoint at the winter solstice. The summer solstice occurs in the middle of Solar Summer, which lasts from early May until early August. Solar Spring and Solar Autumn are centered on the respective equinoxes with Spring lasting from February to May and Autumn from August to November.

Thus, Groundhog Day is, in my mind, the first day of Solar Spring. This is quite important to me because my moods and energy levels relate very directly to solar strength and daily duration. I feel much better when there is more sun and the rapidly increasing solar intensity and day length of Solar Spring are a shot of rejuvenating tonic regardless of the air temperature. I feel the dark days are again behind me, I have survived another winter.

If I could, I would make February 2nd the start of the New Year. Since I cannot, celebrating Groundhog Day is a good alternative. Besides, indirectly, the day celebrates weather and climate: two of my favourite topics and the source of so much personal enjoyment.

So, to all my friends and fellow meteorologists out there. Lighten up! Raise a glass and drink a toast to The 'Hog. May it always signal a new beginning.

A postscript to Groundhog Day 1998, Willie and Phil both saw their shadows today, so hunker down for six more weeks of winter if you believe The Shadow.


Written by
Keith C. Heidorn, PhD, THE WEATHER DOCTOR,
February 2, 1998


The Weather Doctor's Weather Almanac Celebrating Groundhog Day
©1998, Keith C. Heidorn, PhD. All Rights Reserved.
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