The NWS released their new monthly and seasonal outlooks today. For January they are calling for an increased chance of above average temperatures for Illinois. Much of Illinois has an increased chance of above average precipitation as well.
The January-March outlook for Illinois is for an increased chance of above average precipitation and above average temperatures.
If you were not looking forward to a repeat of last year’s winter, this is good news. An increased chance of above average temperatures does not mean you will be playing golf in Illinois in mid-January. But it puts you in better shape than January 2011, which came in at 3 degrees below average.
Why the more upbeat forecast? The current La Niña event occurring in the Pacific has been much weaker than expected, and forecasted to stay so for the rest of the winter. These new forecasts for temperature and precipitation reflect the weaker La Niña event. As noted in an earlier post, November was the sixth wettest and ninth warmest on record. And the first half of December has been above average on temperature and precipitation in most locations.
Revised Winter Forecast from NOAA
NOAA has revised their winter outlook for the U.S, according to a recent post on their ClimateWatch Magazine. An earlier outlook had northern Illinois with chances of well below normal temperatures. The new outlook (below) has pulled the colder outlook out of Illinois as well as expanded the area in the southern half of Illinois with an increased chance of above normal temperatures. So overall, a milder winter is expected in terms of temperatures.
The precipitation outlook for this winter remains unchanged for Illinois. Most of the state, except for far western Illinois, has an increased chance of above normal precipitation. Unfortunately, NOAA does not do a snowfall forecast. Research indicates that the Great Lakes region has better chances for above normal snowfall during past La Niña events. However, the weaker than expected La Niña event this winter and the slow start to the snowfall season suggest that the pattern of increased snowfall during La Niña winters may not pan out this year.
The winter outlook covers the period of December-February, the heart of the winter weather season in most of the U.S.
NOAA Winter Forecast
The NOAA winter forecast was released last week. They say,
For the second winter in a row, La Niña will influence weather patterns across the country, but as usual, it’s not the only climate factor at play. The ‘wild card’ is the lesser-known and less predictable Arctic Oscillation that could produce dramatic short-term swings in temperatures this winter.
Overall, northern Illinois is expected to have increased odds of being colder and snowier than normal – similar to last year. Here are the details. Below the forecast is a refresher on the winter of 2010-2011 that we all knew and loved.
Temperature:
For Illinois, the northern third of the state is expected to have an increased chance of below-normal temperatures. The southern two-thirds of the state has equal chances of above, below, or near-normal temperatures.
Precipitation:
Almost all the state, except for far western Illinois, is expected to have an increased chance of above-normal precipitation. Far western Illinois has equal chances of above, below, or near-normal temperatures. Although NOAA does not offer a winter snowfall forecast, increased precipitation in the winter months usually means increased snowfall.
Winter of 2010-2011
Here are the temperature map and snowfall map for the Midwest for the winter of December 2010 to February 2011. Both maps are expressed as departures from the 1971-2000 averages. The winter was both colder and snowier than average across the Midwest. Meanwhile, precipitation (rainfall and the water content of snow) was right at average for the winter.
October and Fall – Warm and Dry in Illinois
The NWS Climate Prediction Center has released their outlooks for October and October-December. For Illinois there is an increased chance that temperatures will be above-average in both the October and October-December time frames. Also there is an increased chance that precipitation will be below-average in both October and October-December.
As posted earlier, this forecast is consistent with the known impacts of the rejuvenated La Niña event occurring in the Pacific Basin. La Niña tends to give us warmer and drier than average conditions in fall. Last fall was a classic example of this with temperatures 1.2 degrees above average and precipitation 12% below average.
