Record Dry Summer 2012, Will it Continue?
by Cody Matz
August 31, 2012 8:30 PM
What a summer it has been. From record heat to record drought we have seen just about anything imaginable in the last few years. It really is incredible when you stop and think about it that many locations went from the wettest summer on record just 2 years ago to now the driest summer on record. Sioux Falls actually broke the nearly 120-year-old record by more then three quarters of an inch to come in under 3 inches of total rainfall for the summer. It was also the driest summer ever recorded in Yankton with less than 2 inches of rain. But you combine the extremely dry conditions with temperatures well above average and you get one miserable summer. Highs topped 100 degrees for the first time in 6 years in Sioux Falls and several other locations plus many areas have more then doubled their yearly average of 90°+ days. Granted, not all of us hate the heat and businesses that thrive on warm weather sure did benefit, but many suffered through this awfully long summer. Now that the Meteorological summer of June, July, and August is over, we take a look at some of the numbers. You will find out how far above average we really were and see just how dry we have become, plus what we can expect in the road ahead.
Well, we started with the drought so we might as well finish that subject. Meteorological summer around the northern plains is usually a pretty good balance of extreme heat and torrential downpours, very similar to the rest of the country. Our area averages 8-10 inches of rain west of I-29 to 10-12 inches of rain east of I-29. This year was obviously far different with a record dry July for nearly a dozen cities, extremely dry June, and a somewhat dry August. Below is a look at 14 cities across the area showing rainfall totals through the summer and then comparing that to average with some of the numbers down right astonishing.
It was actually wetter in many parts of the desert southwest, like Phoenix Arizona then it was in some areas around here. Both Yankton and Sioux Falls had the driest summers on record with less then a third of average summer time rainfall.
One of the other amazing feats about this past summer was just how quickly the drought spread. Below are two images from the U.S. drought monitor. The first one is for the week of June 12th and the second one is for this past week, the end of August.
Pretty incredible when you look at is next to each other going from normal or wet conditions in the first part of June, to a full blow extreme drought in just a few short weeks. Much of this drought was caused by almost no rain in June and July. Most locations actually faired decently when we got to August. Below are the final rain totals for the month of August.
In many cases, rainfall was less then an inch below normal. On any other year, this wouldn’t have been a catastrophe. But considering we went into August extremely dry, this just adds to the problem.
The summer of 2012 was also very hot, exacerbated in many cases by the on going drought. Remember that water is able to hold a steady temperature much easier then rock, this is why you have very little temperature change when you are next to an ocean. This is why someplace like Seattle rarely gets really hot or really cold, its because of the 40°-55° ocean water that it sits on. Well obviously South Dakota is far away from a large body of water so we depend on soil moisture to keep our temperatures fairly stable… at least stable for us. So when you lose that moisture, your soil is able to warm up and cool down more efficiently therefore you often have much warmer days and slightly cooler nights during the summer. A moist ground could literally be the difference between a high of 105 versus a high of 95. This is likely one of the contributing factors of the heat this summer and also why heat and drought go hand in hand. But the dry soil can have an impact on winter temperatures as well, but just the opposite affect. With dryer soil, temperatures can fall more efficiently too, so if we continue with low amounts of precipitation, then overnight lows through the winter could be much colder then normal. There are many contributing factors that would play into these lows, so it may not happen on many occasions, but its possible.
The average temperatures were far warmer then normal over the summer, check them out below.
These numbers show the average temperature through the summer months. We were 2-5 degrees warmer then a typical summer. I realize this doesn’t sound like much, but a couple of degrees over a season can make a HUGE difference. Take the last ice age for example, the average temperature of the planet was just 8 degrees cooler. Granted that’s on a much larger scale, but I hope you see my point. A few degrees can make a world of difference.
So now the question on everyone’s mind is, will this continue?? Well, for our sake, I hope not. But the Climate Prediction Center (CPC) issues forecasts months in advance using a wide array of devices and techniques. But these forecasts are not what you would see on the news. The forecasts are pure probabilities. The CPC shows the probability of temperatures above and below average as well as precipitation. So the first image below is the probability of having above, normal, or below average temperatures for the 3 month period of September, October, and November. The second image is the probability of having above, normal, or below average precipitation for the same time period.
These show that there is a higher probability that our area, and much of the U.S. for that matter, has a higher probability of experiencing temperatures above average for the next 3 months. Remember though that these forecasts can be rather vague and don’t show day-to-day or even week-to-week temperature fluctuations. This means that we could have below average September and October, but a largely above average November and end up with temperatures above average by combining all 3 months. But it does show that there is a higher probability of more warm spells then cold spell for the next 3 months. Same story for precipitation except that there are equal chances for all 3 types, meaning that precipitation will likely be close to normal, but could have some local variations.
The next 2 images are for the same predictions except it is for the winter months of December, January, and February and you will see similar results.
Once again the CPC is expecting overall temperatures to be warmer then average for the northern U.S. with equal chances for all 3 categories for precipitation.
So keep your fingers crossed that our chances for above average precipitation get better as we move forward because we don’t want things to get any worse.