In an earlier post we examined the NWS Climate Prediction Center forecasts through next summer that included the statement, “Illinois has a higher risk of being both warmer and drier than average through mid-summer. There is an increased risk of being warmer than average in late summer and in fall.”
Taken at face value, the NWS forecast would suggest that we have an increased risk of drought this year. Six months of warmer and drier weather can certainly do that.
However, the key factors in this forecast will be how the El Niño winds down and if La Niña shows up. The chart below is the forecast showing the odds for how things may play out in 2016. The red bar represents the odds of El Niño. The odds are now at 100% and slowly decreased for the next several 3-month time frames. By May-June-July (MJJ), there is only a 40 percent that El Niño will still be around. At that same time, there is an almost 50 percent chance that we will return to average or “neutral” conditions (green bar).
In the meantime, there is a small, but increasing chance that La Niña could appear (blue bar) and the odds reach 40 percent in August-September-October. Take my word for it, you don’t want La Niña showing up. In Illinois we have a pattern of warmer and drier conditions in the critical July-August time frame during La Niña. A return to neutral conditions is more favorable with near-average conditions in July and August.
Another thing to consider is that El Niño and La Niña are not the only two players in town. Indeed, other weather patterns can overwhelm the influence of these two. For example, we have had several springs in recent years with short periods of a very active storm pattern, resulting in very wet conditions.
What does history tell us?
The NOAA Climate Prediction Center (CPC) released their seasonal outlooks today. Illinois has a higher risk of being both warmer and drier than average through mid-summer. There is an increased risk of being warmer than average in late summer and in fall.
CPC also stated in a January 14 release that the “strong El Niño is expected to gradually weaken through spring 2016, and transition to ENSO-neutral during late spring or early summer.”
In addition, there is a chance that La Niña conditions (the opposite of El Niño) could develop in the summer or fall time frame. Unfortunately, the appearance of La Niña in summer or fall in Illinois typically means hot, dry weather. I will discuss this more in a separate post.
This is the first time I can remember CPC forecasting an increased risk of warmer and drier conditions so far out for Illinois. If the forecast comes to pass, this could be a challenging summer.
February: Illinois has an increased risk of being both warmer and drier than average.
February – April: Illinois has an increased risk of being both warmer and drier than average.
May – July: Illinois has an increased risk of being both warmer and drier than average.
August – October: Illinois has an increased risk of being warmer than average. No forecast on precipitation.
The National Centers for Environmental Information (NCEI) reported that the US experienced the second warmest and third wettest year on record, based on records going back to 1895.
What is amazing to me is that all of the lower 48 states were warmer than average. From the report …
The 2015 annual average U.S. temperature was 54.4°F, 2.4°F above the 20th century average, the second warmest year on record. Only 2012 was warmer for the U.S. with an average temperature of 55.3°F.
Here is what US temperatures look like over time. While the linear trend is 1.4 degrees over the last century, the pattern is more complex with much cooler temperatures in the early 20th century, followed by warming in the 30s and 40s, before cooling slightly in the 60s and 70s, and then warming since the 1980s.
Annual temperature for the US from 1895 to 2015. The blue line is a linear trend showing a 14 degree warming over the last century. Plot courtesy of NCEI.
The old statistical joke is that a person with one foot in the fire and one foot in a bucket of icewater feels comfortable – on average. That describes Illinois for January. In round numbers, the first 9 days were 7 degrees above average. The next five days were 6 degrees below average. So we are a little warmer than average for the month, but you wouldn’t know from this week’s weather. Here is how it looks in a chart:
According to the National Weather Service, the cold weather will continue through the middle of next week before warming. Here are the forecasted lows for Monday, showing the lows dropping below zero for northern and central Illinois, and in the single digits for southern Illinois. That will probably be the coldest morning of the week.
So far this winter, central and southern Illinois have seen little or no snow. Here are the totals through January 6 for this winter. Areas north of I-80 have seen amounts in the 10-15 inch range, which is close to average. However, the snowfall totals drop off dramatically southward with much of central Illinois reporting only 1 to 4 inches. And south of Interstate 70 no measurable snow has been reported so far this winter.