October seems to be flying by and that means winter is right around the corner. Some places north of Eau Claire have already seen their first snow of the season. So what does that mean for this winter? Well, NOAA's Climate Predicition Center released their first 2012-2013 Winter Outlook to give some insight into what may happen this winter.
Before we talk about their findings, we should talk about what is analyzed when they make these outlooks. Here's the long list of weather patterns and conditions they take into consideration among others:
1) El Nino or La Nina conditions in the Pacific Ocean. La Nina is colder than average sea-surface temperatures in the eastern Pacific while El Nino would be warmer than average sea-surface temperatures there. If temepratures are around average, it's known as La Nada or Neutral. That looks to be the case this year.
2) Climate trends over the past 10 to 30 years in respect to temperature and precipitation.
3) The Tropical 30-60 Day Oscillation can impact climate variability within seasons. The oscillation is basically an area of disturbed weather in the tropics that takes 30 to 60 days to travel around the globe and can impact weather patterns around the world.
4) The North Atlantic Oscillation and Pacific North American Oscillation are weather patterns up in the Arctic area that can impact temperature patterns here in the United States, especially, in the cold seasons. These phenomena are highly unpredictable past one or two weeks. They are considered in the outlook but are not reliable predictors when making the winter outlook.
5) The Pacific Decadal Oscillation is a pattern like El Nino and La Nina that impacts the tropics, the North Pacific, and North American regions. This pattern varies over a much longer time then the El Nina and La Nina pattern (also known as ENSO).
6) Looking at dry and wet soils from the spring and summer along with snow cover from the past winter.
7) Statistical forecast tools
8) Climate forecast models
So let's now get into the forecast. Last year's winter was crazy! Absoultely bonkers, and pretty much everybody including NOAA bombed the winter forecast. This winter may not be any easier to forecast. Unfortunatley, we're getting a bit of curveball ahead of this season. Earlier this year it looked like the Pacific was heading for El Nino and the signal for that was there. Recently, however, that signal has subsided. A friend of mine from TMJ4 in Milwaukee, who was in the conference call with the Climate Predicition Center when talking about this outlook, said they have relatively high uncertainity with this forecast due to the unusual nature of that El Nino signal subsiding in recent months. So this should be an interesting winter.
In the outlook they are forecasting a La Nada or Neutral winter for the Upper Midwest. That means there is neither a El Nino or La Nina in the eastern Pacific. This meteorological winter (December 1-February 28) is forecated to have these two general traits:
Equal chances of above normal, normal, or below normal temperatures.
an enchanced chance (33 to 40%) of below normal precipitation.
It should be noted we are talking about precipitation in general that means rain and snow. That doesn't necessarily mean we are going to see less snow this winter, but because we are seeing a below normal precipiatation forecast it may be safe to assume snow will be below normal this year.
So as far as this forecast goes, we'll see what happens. However, there's some other things we can look at as well. We can look to the past for clues as to what this La Nada or Neutral winter may hold. It turns out La Nada winters like this can be HIGHLY variable for our area. The National Weather Service out of La Crosse put together these number for La Nada winters, specifically, in La Crosse. However, we can make the case that this generally holds true in Western Wisconsin. First below are the 1980-2010 normal winter temperatures and normal precipitation for La Crosse.
NORMAL WINTER TEMPERATURES
December 29.1° 14.2°
January 25.9° 8.9°
February 31.4° 13.6°
NORMAL WINTER PRECIPITATION (Liquid)
So there we have a sense of what is “normal” when it comes to a winter in Western Wisconsin by using La Crosse as the example city. There have been 21 neutral or La Nada winter in Western Wisconsin since the 1949-50 winter. Below is a break down of the numbers when it comes to temepratures, precipitation and snowfall. Here you'll really see how highly variable these winters can be.
11 Colder Winters than the 1980-2010 normal
9 Warmer Winters than the 1980-2010 normal
Average: 20.5 degrees or 0.9 degrees below the 1980-2010 normals
Coldest: 12.8 degrees in 1978-79
Warmerst: 29.2 degrees in 2001-02
12 Drier Winters than the 1980-2010 normal
9 Wetter Winters than the 1980-2019 normal
Average: 3.41” or 0.29” below the 1980-2010 normals
Driest: 0.98” in 1956-57
Wettest: 5.17” in 1966-67
11 Snowier Winters than the 1980-2010 normal
10 Less Snowier Winters than the 1980-2010 normal
Average: 46.5” or 3.2” above the 1980-2010 normals
Least: 21.8” in 1980-81
Greatest: 78.7” in 1960-61
Pretty interesting right? There's really a quite even split in La Nada Winters here in Western Wisconsin when it comes to temperaturs, precipitation, and even snowfall. If we go striclty by averages for each, we could forecast that this winter may tend to have below normal temperatures, below normal precipitation, but above normal snowfall. Doesn't mean that will be the case, but that's what an average La Nada winter looks like in Western Wisconsin.
We'll have to see where the winter of 2012-13 falls into this split. I will say though, I highly doubt we will see such a warm winter like the one we saw last year. It was the 5th warmest winter in Eau Claire and the 6th warmest in La Crosse. Also, I doubt we will see the lack of snow we did last year. At the same time, I don't think we see the insane amount of snow we did two years ago. No matter the overall outcome, without a doubt, it will still be cold at times and we'll see some snow. All part of living in Western Wisconsin during the winter.