The NWS Climate Prediction Center posted their latest outlook for December and December – February (winter). The temperature outlook for December is for equal chances (EC) for above, below, and near-normal temperatures. The precipitation outlook for December is a little more interesting with an increased chance of above normal precipitation in the southern half of Illinois. The rest of the state is in the EC category.
There is not much to report on the December-February outlook for Illinois with the state in EC for both temperature and precipitation, except for an increased chance of above-normal precipitation in far southern Illinois.
Part of the reason for the bland outlooks is that the Climate Prediction Center expects near-normal temperatures in the eastern Pacific Ocean along the equator. That means there is no El Niño or La Niña expected for this winter.
I looked at three winters that had a similar setup in the Pacific Ocean (slightly raised sea-surface temperatures but not a full-blown El Niño event). They are the winters of 1979-80, 1990-91, and 2003-04. In Illinois, each of these winter were slightly warmer than normal – on average by half a degree. Two out of the three had below-average precipitation (1979-80 was 2.2 inches short, 2003-04 was 1.3 inches short, while 1990-91 was 1.4 inches above). All three had below-average snowfall in the north. However, two out of three had above-average snowfall in southern Illinois (1979-80 and 1990-91). See the maps below for more details on snowfall.
A Warm Fall for Illinois?
NOAA’s Climate Prediction Center released their latest monthly and seasonal outlooks today (Thursday). In the figure below, the outlook for October in Illinois is for an increased risk of above-normal temperatures and below-normal precipitation. The 3-month outlook for October-December in Illinois is for an increased risk of above-normal temperatures. Their precipitation outlook is neutral at this time.
That’s not the best news for drought recovery but it might make it easier on farmers for fall harvest.
One factor that could come into play this winter is El Niño. In fact, the CPC says an El Niño event is likely to arrive some time in September, according to their latest advisory. However, in the last two winters the Arctic Oscillation has played a major role in our winter weather. Two winters ago it was in the negative phase and dumped lots of cold air into Illinois. Last winter it was in the positive phase and prevented a lot of cold air from reaching us. Unfortunately, we can only forecast the Arctic Oscillation out to 14 days.
Latest Outlooks for September and the Fall
On Thursday, NOAA’s Climate Prediction Center released their outlooks for September and the 3-month period of September – November. For Illinois, they foresee an increased risk of above-normal temperatures and below-normal precipitation in September. Also, they foresee an increased risk of above-normal temperatures for September – November. They are taking a neutral stand on fall precipitation, saying that there are equal chances of above, below and near-normal precipitation.
The other news they have is that their drought outlook (second figure) shows expected improvement in the drought north of Interstate 74 in the upcoming months. Some improvement is expected in southern Illinois. However, they expect drought to persist in western Illinois through at least the end of November.
Bad News for August in Illinois
The NOAA Climate Prediction Center has updated their forecast for August. It’s not good news for Illinois with an increased risk of above-normal temperatures and below-normal precipitation.
