The Daily Parker

Politics, Weather, Photography, and the Dog

More about our really warm winter

The Tribune has a graphic this morning pointing out a number of things about our lack of snow this past winter. It turns out, the snowfall on March 4th was the earliest last snowfall. That is, in the rest of recorded history (back to 1884), we've always gotten snow later than March 4th. Until this year.

Our entire season gave us only 11 days with 25 mm or more of snow on the ground (normal is 43); it was one of only 10 seasons (out of 128) with less than 500 mm of snowfall total (normal is 932 mm); and it's the second-shortest interval from first to last snowfall ever, at 117 days (normal is 174).

Of course, snow has fallen in 40 Mays of the 128 in history...so this could all be completely wrong. We've even gotten snow in June (on 2 June 1910). But it looks for now like we can add one more quantification to our wonderfully mild winter.

April is the weirdest month

At least this year, in Illinois, where the average temperature is actually below March's—and it's still above normal:

The statewide average temperature for April 1-22 is 12.3°C. The statewide average temperature for March was 12.8°C, based on the latest numbers from NOAA. That means that April was almost a degree [Fahrenheit] cooler than March. What makes this even more freaky is that the April temperatures are still 1.9°C above normal!

BTW, the statewide normal monthly temperature is 4.8°C for March and 10.9°C for April, a ten degree [Fahrenheit] rise.

State Climatologist Jim Angel concludes by pointing out that we've only had one April in recorded history that was cooler than March, back in 1907. (Recorded history goes back to 1895.)

"Theory" means "explains the facts"

Theories also have predictive value; that is, in order for a hypothesis to graduate to theorydom, it has to fit all the available facts and predict future events. You know, like anthropogenic climate change, which gets closer to being a true theory every day. For example, via Fallows, a paper written in 1981 seems to have predicted it pretty well:

Sometimes it helps to take a step back from the everyday pressures of research (falling ill helps). It was in this way we stumbled across Hansen et al (1981) (pdf). In 1981 the first author of this post was in his first year at university and the other just entered the KNMI after finishing his masters. Global warming was not yet an issue at the KNMI where the focus was much more on climate variability, which explains why the article of Hansen et al. was unnoticed at that time by the second author. It turns out to be a very interesting read.

[T]hey attribute global mean temperature trend 1880-1980 to CO2, volcanic and solar forcing. Most interestingly, Fig.6 (below) gives a projection for the global mean temperature up to 2100. At a time when the northern hemisphere was cooling and the global mean temperature still below the values of the early 1940s, they confidently predicted a rise in temperature due to increasing CO2 emissions. They assume that no action will be taken before the global warming signal will be significant in the late 1990s, so the different energy-use scenarios only start diverging after that.

And the band played on...

It was good while it lasted

Chicago's record-shattering run of above-normal temperatures ended yesterday:

The abnormal, all-too-often record warmth, couldn't continue indefinitely. For 26 consecutive days, Chicagoans were treated to temperature levels which would have been at home in June and July. They were without precedent in March and early April.

The impact of that warmth continues, even in the midst of noticeably cooler air here. And while Easter weekend temperatures are expected to rebound to the 60s, an even cooler air mass seems determined to settle southward over the eastern half of the country next week.

April's opening 5-days continue to run 3°C warmer than the same period a year ago. The results of the abnormal warmth have been tangible. Vegetation in and around Chicago has bloomed 4 to 6 weeks early, a trend which has already spawned an extremely challenging pollen-season through which many continue to suffer.

Thursday marked the first day in 27 in which temperatures finished "below normal".

Next week it's supposed to be "seasonal," which could include a freeze.

A chill in the air

The opening days of April have seemed a lot cooler than all but one or two days in March, but as it turns out, we're still above normal:

Despite the chilly feel to the air in recent days, the books closed on a 26th consecutive above normal average daytime temperature here Wednesday. The day finished 4.4°C above normal with a high of 14.4°C.

Any clarity in the forecast for the summer, though? The Climate Prediction Center still sees only a 33% chance of above-normal temperatures through the middle of June, as the La Niña that gave us the warmest March ever winds down to a neutral state over the next couple of weeks.

If we have the warmest spring followed by a cooler-than-normal summer, there will be much rejoicing at The Daily Parker.

Analyses of the heat wave

Illinois State Climatologist Jim Angel rounded up some explanations of last month's record heat. Here's the NWS Chicago office:

The 2.7°C difference between the average temperature for March 2012 at Chicago-O'Hare and the previous record for warmest March is by far the largest difference between 1st and 2nd place between record warm or cold months in Chicago. The second largest difference between 1st and 2nd place is the 1.7°C separating the average temperature of January 1880 (4.3°C) and January 1933 (2.6°C) for the warmest Januarys on record in Chicago.

The 8.67°C departure from normal for March 2012 is the 3rd largest departure from the 1981-2010 normal for any month in Chicago. The only months that had higher departures from normal were January 1877, which with an average temperature of 4.3°C, was 8.9°C above the 1981-2010 average January temperature, and December 1877, which with an average temperature of 6.3°C, was 8.72°C above the 1981-2010 average December temperature.

For a more technical discussion, check out NOAA's analysis, which concludes:

A black swan most probably was observed in March 2012 (lest we forget 1910). Gifted thereby to a wonderful late winter of unprecedented balmy weather, we also now know that all swans are not white. The event reminds us that there is no reason to believe that the hottest, "meteorological maddest" March observed in a mere century of observations is the hottest possible. But this isn't to push all the blame upon randomness. Our current estimate of the impact of GHG forcing is that it likely contributed on the order of 5% to 10% of the magnitude of the heat wave during 12-23 March. And the probability of heatwaves is growing as GHG-induced warming continues to progress. But there is always the randomness.

April, so far, has been bog-standard normal.

Even I'm disappointed

Yesterday, the forecast for tomorrow's Chicago weather called for—no April Fool's joke here—32°C. Just a few hours ago the forecast had changed to a more comfortable 25°C, which is about as close to ideal as I can imagine. Just now, though, the National Weather Service says to expect nothing better than 13°C. Aw, come on.

On the other hand, Chicago had its warmest March in history, at 11.9°C, which beat the previous record (set in both 1945 and 1910) of 9.2°C. So, you know, the weather hasn't been that awful lately.

Maybe we're not in for a hot summer?

Illinois State Climatologist Jim Angel has crunched the numbers, and thinks (contra my own fears) that we might not get melted into little puddles of goo this summer after all:

Historically, a warm March has been followed by a colder-than-normal April on average (first map). That’s true not just in Illinois but across the U.S. On the other hand, precipitation for those same April periods was a mixed bag in Illinois (second map). Most of the state was near-normal while west-central Illinois was slightly wetter-than-normal.

I considered the entire May-August period in one set of maps. One popular question I get is “Does this warm weather now mean that we will get a hot summer?” At least historically, the growing season following a warm March does not show a pattern of above-normal temperatures. On average, they have been remarkably mild in temperature.

I still worry that the really warm lake temperatures and the lack of snow cover during the winter, followed by an unprecedented 8 days of 27°C weather this month (not to mention the hottest March in recorded history), can't help but yield a brutal summer.

Angel has the data, though. I tend to trust data. I should be reassured...but I'm also from Chicago.