The Preamble
Just like last year, don’t worry, I know that there are, like, infinity “Winter Outlooks” floating aorund the web. Everyone has one of these. And they all say something different. They all have varying degrees of information, too. Some just talk temperature, others just talk precipitation, while a handful give vague can’t-be-counted-as-incorrect-of-correct-style forecasts, too.
Here are a sample from the top offerings every year…
Accuweather:
Weather Channel:
The Climate Prediction Center:
The Old Farmer’s Alamanc
The Farmers’ Almanac
All of these are fine resources, I’m sure. I’ve got nothing but high praise for forecasters willing to go out on a limb to suggest things like “wintry” weather during, well, Winter. This isn’t about their accuracy, it is about giving an actual meaningful look at a winter outlook for a smaller region based on actual science and math. Hooray!
This forecast is done specifically for southern Mississippi. However, if you live south of I-20 and between, say Lake Charles, Louisiana and Destin, Florida this forecast will likely apply to you, too.
The 2019-2020 Winter Outlook
Looking at the November 1st through February 29th time frame…
Based on the available data, using the regional responses to ENSO, the PDO, and the NAO as a guide, there is a better chance for cooler-than -average conditions and an increased chance for drier-than-average conditions across the region.
Broken down by month….
The numbers above are based on past climate data, but given that data and a lookat the PDO and NAO as well as the overall teleconnection patterns during the next either weeks, here is a look at the 2019=2020 Winter Outlook broken down by month:
November: Warmer & Drier
December: Cooler & Drier
January: Average & Drier
February: Cooler & Drier
Keep in mind that Cooler and Warmer don’t indicate the amount of deviation from normal, just that there will be a deviation of more than one-degree from normal. Same goes for drier versus wetter. Just because there are four months of drier-than-normal expected doesn’t mean that the lack of precipitation will be severe, just that it won’t meet within 0.75″ of normal.
How’d we get here?
Analogs. I really like using analogs for seasonal outlooks because they do – in general – a decent job. They only work well when we have multiple near-analogous years to pull from, and it just so happens that this year we do!
So, a lot like in 2015 and 2017, there is more data to pull from for this winter’s outlook.
The analogous years when taking ENSO into account are 58-59, 59-60, 66-67, 69-70, 77-78, 80-81, 92-93, 95-95, 03-04, 05-06, 16-17. Some years were more analogous than others, but this built a good repository of potential outcomes to pull from. An analogous season I think will hold up really well is 1969-1970, but more on that at a later date.
The ENSO forecast from the Climate Prediction Center favors a Neutral pattern to continue with the hints that a weak El Nino is the next most likely scenario.
So, we have to look at the ‘run-up’ to winter to find analogous years. Which years featured an El Nino during the previous Winter, Spring and into Summer. And one that fell apart while moving through Summer.
To balance the variability within the data sets, I’ve included Two years that drifted into a weak La Nina during the Summer/Fall and two years that drifted into a weak El Nino during the Summer/Fall.
| Years | Wi | Sp | Su | |
| 58-59 | EL | EL | Neutral | |
| 59-60 | EL | Neutral | Neutral | |
| 66-67 | EL | EL | Neutral | |
| 69-70 | EL | Neutral | EL | |
| 77-78 | EL | Neutral | EL | |
| 80-81 | EL | Neutral | Neutral | |
| 92-93 | EL | EL | Neutral | |
| 95-96 | EL | Neutral | LA | |
| 03-04 | EL | Neutral | Neutral | |
| 05-06 | EL | Neutral | LA | |
| 16-17 | EL | EL | Neutral |
That gives us 11 years to pull from. Which, through happenstance, also means that there is a tie-breaker year if things are split.
So what happened on those years?
The chart is broken down with the years/season on the far left, followed by if it was El Nino, La Nina or Neutral, then I broke each month down during that season with if the temperature and precipitation was above average, average or below average. And in this case, “Average” meant readings within 1-degree and precipitation within .75″ of the running 30-year average.
As an aside, using the running 30-year average does present some problems given how climate change has shifted the overnight lows for the region. As shown here, the overnight lows (and therefore the average temperatures) have increased pretty dramatically during the last 100 years. That means data during the last 30 years is going to be naturally warmer than data 70 years ago.
Pulling some statistics out of the data, we can start to make predictions about the years – in the past – that the general atmospheric setup was similar.
For example, if November is warmer-than-average December has never been also warmer-than-average. If December is cooler-than-average, there is a better chance that January is cooler-than-average. And no matter what happens in January, February has a better chance of being cooler-than average.
It also shows that November and January are a bit of a wildcard. There is no real discernible pattern. So for that, we will have to use other tools to decipher a forecast.
What does this mean?
This means that when March 1st rolls around and we look back at the climate data from November 1st through February 29th, the average temperature for all days added up will end up being below average. And that when all of the precipitation data is added up, it will be below average.
It also increases the chances that there are longer dry spells. It increases the chances for longer cool spells.
There is an increased chance for a handful of much colder days (temperatures below freezing at some point during the day). And thus, in a roundabout way, an increased chance for wintry precipitation.
What this doesn’t mean…
This doesn’t it won’t rain. It doesn’t mean it won’t flood. It doesn’t mean we can’t get warm. It doesn’t mean a decreased chance for severe weather. It doesn’t mean it will definitely snow.
