Ready for another winter?
The question that many of you may be asking; will winter happen during “winter” or will winter happen in the “spring” like usual?
It certainly seems like our bigger snow systems have taken place later in the season with the cold air lingering well into March and April.
I will say that the trends for this year show that the pattern is going to be different. But in what way?
That is going to be the focus of this post.
Just remember my disclaimer: long-range forecasting has a very limited skill with snowfall forecasting just barely above the “0″ mark in skill level. Having said that, we (meteorologists/climatologists) are gaining valuable data each year on ocean and weather patterns that are slowly, but surely, creating a story-line of how our atmosphere works. So while these forecasts are meant for more entertainment than anything, they do contain legitimate data trends that will be tested once again as we hunt for that seemingly one variable that “drives” the winter season. Sometimes it’s El Nino, or La Nina or the PNA or the NAO. Sometimes the sales of bread and milk factor into it (completely KIDDING on this one, though some of you actually believe that).
So let’s dive in...
The winter of 2017-2018
This is a pic of me out in the WAVE 3 Weather Garden the morning of March 20th when snowfall rates were nearly 2″ per hour in Jefferson County. I ended up with 11″ at my house that morning.
Temperature Departures (Louisville)
December 0.9° BELOW Normal Snow: .2″ Warmest: 69° Christmas: 32° with light snow showers but under the 1″ White Christmas requirement
January 2.2° BELOW Normal Snow: 5.0″ Warmest: 66° Coldest: 0°
February 6.2° ABOVE Normal Snow: 0.8″ Warmest: 82° Coldest: 14° Valentines Day was warm and rainy.
March 2.5° BELOW Normal Snow: 11.9″ Warmest: 69° Coldest: 25° Major snow event on the first day of spring.
April 4.8° BELOW Normal Snow: 1.2″ Warmest: 83°
Season snowfall was 19.1″, however most than half of that fell outside of “meteorological winter”.
Winter was certainly delayed....
LOOKING AHEAD...THE FACTORS
EL NINO or EL NIN-YES?
This is where the Pacific Ocean waters warm. We had a La Nina last year (cooling of the waters). These can certainly impact our weather but not always as it really depends on the intensity and during of that warming or cooling. You can see how we are starting to warm at the very end of the chart below.
We have had some big snow events in other El Nino years (1978, 1994, 1998, etc.). The forecast is for it to keep warming to get into El Nino status (above 0.5°C or 3 consecutive months). A 1.0 to 1.5 is a weak to moderate El Nino. The strength does make a difference. It should be noted that water temperatures has surged in warmth just in the past 8 days. That is a bit more alarming when it comes to the forecast as we may end up in a moderate El Nino this winter. What does that mean? I will explain down below.
This certainly has been a headline. It started really in March with some big wet snow events. Then we moved right into heavy rain/river flooding in the spring. Not once, but twice with the Ohio River flooding coming awful close to Thunder Over Louisville time but it still left the Great Lawn a muddy mess.
We picked up more heavy rain events (including Derby Day) that continues even as we close out October. You can see by this chart just how the precipitation has focused in our area since January.
The question here, will this continue?
The drought certainly has been trimmed way back. That is significant in that a large area of drought leads to a natural pressure. This would mean a much more active storm track to its east. Which is basically where the wet pattern has been locked in.
This is the JAMSTEC model that actually has had a good record on our winters. Doesn’t win them all, but does pretty good. So this is one of my favorites.
Forecast Precipitation Departures Dec-Feb
Forecast Temperature Departures for Dec-Feb
Many forecast are lining up with the above. And I like this look. It is the El Nino factor that still makes me wonder.
The best way to explain this is these are upper atmosphere wind patterns that tend to repeat. The idea is that you can track them even months down the road to give you an indication of what types of pressure systems (low/high) will cross through any one location. We can even pick out the potential intensity of them. This is a growing forecast method being used for long term. It isn’t perfect of course as accuracy drops off the more out in time you go.
It does feature more ridging over the SE which I do agree with to an extent. Just a slight one can really ramp up winter storm potential in our region.
It can even look at the potential for snow with some of the systems over the next few months. Granted the probability is very low, I can’t recall seeing so many in the outlook for us. Hmmm.
SO WHAT DO THEY ALL SAY?
Each factor tells its own story. And there are many more factors to look at (i.e., low national tornado count). I just don’t have the time to get them into the blog. I hope you can at least see that the signals show that something different is going to happen this winter. The rapid warming of the Pacific does raise some eyebrows as this may really ramp up the moisture for the SE part of the country (more than it already has) with a complicating factor of cold air dropping in from the Great Lakes/Ohio Valley. I don’t see it being overly cold but cold enough for some challenging winter storms and perhaps one or two blockbuster type events. One of the more promising setups I have seen for such in a few years. It just needs to be that careful balance of El Nino moisture train and the cold attacks from the north. If El Nino ends up stronger than expected, we could find ourselves much warmer. But that still remains in the “iffy” category and not in the “likely one”.
Having said all of that, below is the thinking of what the pattern looks to bring us overall for the season. This will include some warm surges and cold attacks, but the “battles” are what look to make this seasons more fascinating instead of some of the “all warm” or “cold and dry” winter’s of the past.
WINTER FORECAST 2018-2019
National maps are included in the video to breakdown the overall theme of weather events and temperature departures.
And just for fun, here are the guesses from the WAVE 3 News Storm Tracking Team when it comes to the date of the FIRST 1″ OF SNOW AT LOUISVILLE INTERNATIONAL:
...and the guess for the LARGEST SNOW EVENT AT LOUISVILLE INTERNATIONAL:
Be sure to watch the video to get more details and a better visual sense of the data being analyzed.
Thanks everyone for watching/reading and let’s Bring On The Snow !!!
Credits: National Weather Service Louisville, NOAA, CPC, constantchaos.com, JAMSTEC and Twix.