The last time I can remember wearing shorts on the first day of spring was, well, never. But to be fair my memory of what apparel I wore on any given day is about as sharp as a bowling ball. Needless to say our warm start to 2012 is unprecedented. And we certainly finished with a grand finale the last week of winter.
The previous 8 days (March 14th to 21st) have included 5 record highs and 5 record warm-low temps. On March 20th Mitchell International peaked at 83° breaking the record not only for the day, but for the entire month of March! It is also the earliest 80 degree day of any calendar year on record. On March 21st we topped that record when we hit 84°. The reason for the recent record warmth can be attributed to a number of factors. First off we had a mild start to the month with no snow cover. This allows the stronger March sunshine to warm us up when clouds don’t get in the way (with snow cover the sun’s rays are reflected back into space). Next, we seem to have a persistent pattern with high pressure over the east coast and low pressure over the Rockies or Pacific Northwest. The pressure gradient between the two has lead to a southerly wind flow stretching from the Gulf Coast to the Midwest day after day. Large patterns covering the entire country like this don’t break down overnight, they can take days or weeks to change. And most of us got to reap the benefits.
Now the emails and phone calls are flowing in to the FOX6 Weather Center. Viewers are asking are we done with snow? Will spring be just as warm? While our day to day weather is affected by synoptic systems (high and low pressure systems, fronts, etc) crossing the continental U.S. our seasonal climate is not. When it comes to the forecast months at a time our weather is affected by global patterns such as El Nino, La Nina, the North Atlantic Oscillation, and so on. There is a good website at www.cpc.noaa.gov that predicts the chances of a warmer than normal, or colder than normal month/season ahead. The climate scientists working for NOAA are the best at forecasting extended periods, though it can still be a roll of the dice. Check it out if you are curious.
Now back to this year’s sizzling start. If we can compare it to any single year it would be that start of 1990. Our average temp since New Year’s Day is 34.4°, the same time period in 1990 averaged 32.7°. So what happened in April of 1990? The average for the month was nearly +5° above normal. HOWEVER, the first 15 days were ½° below normal. So the warm start really didn’t carry over into the beginning of spring, the warmth simply started up again. Then came May 10, 1990 when a freakishly unseasonable spring snowstorm dropped 3-8” of snow across eastern Wisconsin. Trees that were in full bloom clung to the heavy, wet snow like Velcro. Limbs came down and took power lines with them. So after the warmest start to the year on record we ended up with a typical start to April and a May snowstorm. Of course there is no way to predict if that will happen this year. What it does say is a warm stretch of weather in our tiny corner of the world does not trump what global climate patterns may bring weeks or months down the road.