Winter is sneaking up on us. What will it bring this year?
The leaves have already turned bright shades of yellow, orange and red and thanks to recent storms, trees are already losing their foliage.
The days continue to grow shorter and the nights colder. Signs of the approaching cold season are all around us. No doubt about it, we are on the downhill slide towards winter!
So naturally people are looking ahead and wondering... what can be expected this winter season?
Last winter brought us some of the warmest conditions on record and only seven inches of snow.
There were many factors that contributed to that outcome including the presence of a La Nina pattern in the Equatorial Pacific and a persistent positive phase in the North Atlantic Oscillation (NAO).
As many of you may know, we look to climate indicators such as La Nina or El Nino and NAO to give us an idea of what to expect when forecasting weeks or months in advance.
Much has changed since last season. Let's start with the current state of the Equatorial Pacific.
Water temperatures in the Eastern Pacific are near normal to slightly above normal compared to the 30 year average. This means that we are in a weak El Nino pattern.
There is some uncertainty whether this trend will continue into the winter months. Regardless though, if a weak El Nino persists or we go into a neutral pattern (near normal temps), it will give us little guidance as to what to expect this winter. Only moderate or strong La Nina or El Nino events serve as strong indicators for our winter seasons.
The next item of interest is the current state of NAO (North American Oscillation).
Currently, NAO is in a negative phase and has been for most of the last month. In the winter months, a pattern like this can signal colder and snowier than normal conditions for these parts.
The problem with NAO, is that it becomes highly unpredictable once you start looking out more than a couple of weeks. Hence, this will do little good in helping us determine what this winter will bring us.
Another factor to consider with regards to longrange forecasts is soil moisture. Although recent rains have pretty much eliminated the drought in our area, a severe drought is ongoing across much of the Plains and Central US.
The lack of soil moisture for such a large area directly to our west will almost certainly have a bearing on our weather this winter.
Unfortunately for the folks that are dealing with the drought, it seems likely that the drought will continue through the winter months.
This could mean a couple different things for us. First, without much precipitation this winter across the heartland, it would be very difficult for a snowpack to develop. This will lend itself to milder temperatures for much of the Central US. Not necessarily here though.
With that being said, here's a look at the Climate Prediction Center's temperature forecast for December through February.
CPC believes that much of the Western and Central US will experience warmer than average temps. Near normal temps are predicted for our area and much of the Eastern US. The only area expected to have cooler than normal temps is the Florida Peninsula where the weak El Nino may have it's strongest effects.
As far as precipitation is concerned, CPC has highlighted three areas where either above or below average precip is expected.
Below average is expected for the Pacific Northwest and the Upper Midwest. While near normal precip is forecasted for the Ohio Valley and Northeast, a wetter than normal winter is anticipated across the Gulf Coast.
So what does all of this mean?
It means that without a strong climate signal to rely on such as an El Nino or La Nina event, we have to look towards climatology, which is the study of weather conditions for a particular location over a long period of time.
According to climate, Louisville will see winter high temps averaging between 43 and 48 degrees with lows between 25 and 30 during the months of December, January and February. We'll also see somewhere around 10 inches of precipitation with about a foot of snow during the course of the winter months. (Louisville has averaged 12.4" of snow per season over the last 30 years).
Of course let us not forget how these "averages" are derived. Sometimes you go several years between major winter storms. However, if one happens to occur this year, it will be looked back on as a bad winter.
I guess only time will tell for sure!
Meteorologist Jeremy Kappell