The StormTrack 9 Winter Outlook 2019-2020

STORMTRACK 9 WINTER OUTLOOK 2019-2020

For over 35 years, the StormTrack 9 tradition continues with the annual Winter Outlook! It was my favorite forecast of the year when I was younger growing up in Chickamauga, GA. And, it still is today as I am now the one delivering the seasonal outlook! I will often get asked about the upcoming Winter forecast as early as the Summer. So, I understand the anticipation and how important it is to do my very best!

WHERE’S THE SNOW?

Many of you have asked me that repeatedly the past few winters. Chattanooga only averages a low 3.9” of snow a year. And, even with that low average, we have not had much snow at all the past 4 winters. Winter of 2014-2015 was the last winter with above average snowfall with over 9 inches!

So, with the last 4 Winters having below average snowfall, it should come as no surprise that temperatures were also well above average. The last Winter that had temperatures below average was in 2014-2015, also the last time we had meaningful snow.

WHAT DOES THE ALMANAC SAY?

I always enjoy reading both of the major almanacs (Old Farmers Almanac and Farmers Almanac). They have been publishing Winter forecasts long before me, so I always give them a tip of the hat and respect both publications. Both project wet conditions for the Southeast. But, one projects a “mild” Winter while the other projects a “brisk” Winter. So, a consensus on rainfall, but differ on temperature.

WHAT WOULD GRANDPAPPY SAY?

Our dear friend, the late Don Welch started the WTVC Winter forecasts and “Grandpappy” sayings back in the 1970s. His “go to” Winter signal was the wooly worms. If the wooly worms were brown, then a mild Winter was expected. If the wooly worms were solid black, then a cold winter was expected. If the wooly worm had alternating bands of black and brown, then a period of both warm and cold was expected (which pretty much sums up a normal Winter around these parts!). Based on the viewer reports, the majority of wooly worms had the alternating bands. So, Grandpappy would say a normal Winter is a comin’!

The other Winter predictor Grandpappy used was counting the dense fogs in August. The saying goes that the number of dense fogs in August could predict how many “good” snows could occur the following Winter. Well, Chattanooga had 1 dense fog day in August which Grandpappy would say means 1 good snow!

We’ll tackle the science side of things coming up. But, Grandpappy’s folklore will always be included in my annual Winter Forecast.

STUDYING THE WEATHER PATTERNS

I always look back at past Winter patterns to help get an idea of what could happen this Winter. Past weather patterns could provide some clues and similarities. But, no two Winters are exactly alike. And, simply put, the weather is going to do want it wants to do!

Global weather patterns driven by an El Nino and La Nina can indeed provide some of those clues for a seasonal outlook. The seasonal surface temperature changes in the Pacific equatorial waters and along the South America coast can lead to global weather pattern fluctuations. When warmer sea surface temperatures persist, this is known as "El Nino". When cooler sea surface temperatures are present, this is known as "La Nina". Last Winter we experienced a weak El Nino. But, through most of 2019 the sea surface temperatures have cooled a bit to what is known as a "Neutral" Phase. While studying this global pattern is not the only factor, it can provide a big clue as to the driving forces for the upcoming Winter.

PAST SIMILAR WEATHER PATTERNS

Looking at the past 30 years of data, there are (NUMBER) of Winters with a “Neutral” pattern. The last one being that Winter of 2014-2015 which was the last cold Winter we had. But, including that Winter and others did yield some similarities. Most had below average temperatures across the Midwest, Great Lakes and Northeast US. Here in the Tennessee Valley the temperatures were normal to just a tad below normal. Precipitation likewise had some similarities. A large part of the Southeast including the Tennessee Valley had above normal Winter precipitation. Local snowfall amounts from those previous “Neutral” Winters differed, but more than half were near normal to above normal.

OTHER RESEARCH

Studying the El Nino/La Nina/Neutral ENSO pattern is not the only thing considered for the seasonal outlook. An analysis of the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO) Index and Forecasts help provide a clue to short term changes during the Winter. This helps us no when to expect possible arctic outbreaks during the season.

Another factor I have watched the past few years is the snowfall in Siberia. Several studies have been done that show a link between above average Autumn snowfall in Siberia and above average snowfall in the northern and northeast US. Through a large part of Autumn this year, snowfall in Siberia has been above average.

SO, WHAT DO I THINK?

I am leaning heavily here on the “Neutral” phase of the ENSO (El Nino/La Nina) because of past season similarities. I am projecting Winter temperatures locally to be near normal, which is COLDER than the past two Winters. Extending this forecast into March could even include some below normal temperature stretches. So, as is usually the case here in the Tennessee Valley during a “normal” Winter, there could be periods of both mild and very cold.

Rainfall could again be above normal this Winter. Hopefully not quite as wet as the flooding rain we had last February. But, above normal rainfall and some period of cold could lead to some better snowfall and ice chances than the past few Winters. So, I like our snowfall chances this year and projecting normal snowfall. If I had to put a number on it based on past similar seasons, then a 4”-5” range would be the projection. Again, the average Winter snowfall for Chattanooga is around 4” (3.9”).

Each year I always caution you the threat of ice. Our part of the Southeast can always be vulnerable to ice events. The last two extreme ice events locally occurred in 1960 and 1973 with paralyzing ice storms. It’s been a while, so it’s just something to be aware of!

DEPEND ON US

No matter what happens this Winter, you can always depend on the StormTrack 9 Team. Our forecasting team is 4 members strong who are all dedicated to bringing you the best weather coverage. Keeping you and your family safe every season, you can depend on the StormTrack 9 Team!

And, as we do each year on the first full day of Spring (3/20/20), we will review and grade this Winter Outlook!

David Glenn