Almanac a fun read, but not always on the money
- Herb Broda: Nature Notebook
- February 25, 2021
- 888
"The trouble with weather forecasting is that it's right too often for us to ignore it and wrong too often for us to rely on it." — Patrick Young.
I admit I am a bit of a wannabe meteorologist. I really enjoy comparing weather forecasts with what actually happened on any given day.
A good place to find long-range weather forecast data is the Old Farmer’s Almanac. It’s a wonderful little magazine with a tag line that says it’s “useful, with a pleasant degree of humor.” I’m not sure about the humor, but the magazine is certainly useful and also a fun read.
The almanac divides the U.S. into 18 regions. We are on the border line between the “Lower Lakes” and the “Ohio Valley” regions. Each month is listed by region with mini forecasts that usually span three- to seven-day blocks. Because the forecasts have to be made more than a year in advance, pinpoint accuracy is impossible.
But that’s part of the charm of the almanac’s weather predictions. Although it would be foolish to rely solely on the almanac as a guide for planning an outdoor wedding, it is fun to see just how close the predictions come to reality.
For January of this year, the predictions didn’t match up very well. For Jan. 1-3 the prediction was snowy and cold, but the actual high temps were mild at 45, 48 and 39 F for those days, and there was no snow, just one rainy day.
The predictions for the rest of the month weren’t so good either. For Jan. 4-8 it was to be rainy and mild, but the temperature never rose above 35 F, and there was only a trace of rain. Snow showers and cold were predicted for Jan. 9-16, but five of those days were in the 40s and there was no precipitation.
For Jan. 17-24 the almanac predicted mild temps and periods of rain and wet snow. There actually were only two mild days during the period with wet snow in trace amounts on the majority of days. The remainder of the month, however, was right on with predictions of snow showers and cold.
As forecast, the first three days of February did have snow showers and cold. However, for Feb. 4-15 the almanac called for rain and mild weather, but we had snow, no rain and most temperatures below freezing.
For those of you who love snow, the almanac predicts the snowiest periods are to be from early to mid-March. We won’t have to wait long to check out that prediction.
Growing degree days
Growing degree days are used to estimate when crops and insects will grow and develop. In overly simplistic terms, the GDD, or heat units, are the accumulation of average daily temperatures higher than minimum base temperatures below which growth will not occur.
A certain number of GDD units are needed to trigger growth in a plant. A silver maple tree will be in full bloom in the Wooster area when we reach 42 growing degree days. On Feb. 15 we were at zero growing degree days. How soon we reach the needed number will depend upon how many days of 50 F or above occur locally.
We will have to reach 58 GDD to see the beautiful yellow first blooms of our local forsythia bushes. When that happens, spring is definitely on the way.
When people talk about a “late spring,” they are really referring to a year when we have had fewer than normal base temperature days by a specific date. In overly simple terms, it is a late spring when we have had fewer than usual days of 50 F or higher.
To see a detailed listing of when plants and insect pests in our area emerge, just google “OARDC GDD.” Enter your zip code and The Ohio State Phenology Calendar appears.
It’s a huge list that shows plants found in our area and the number of GDD needed for first bloom or full bloom. Common local insect pests also are included, along with the number of GDD needed for egg hatch and adult emergence.
The Phenology Calendar is an amazing tool and reflects an enormous amount of research needed to compile all of this data.