Spring Outlook - Quiet Or Active Severe Weather Season? - WMC Action News 5 - Memphis, Tennessee

Spring Outlook - Quiet Or Active Severe Weather Season?

© Sea Surface Temperatures NCEP © Sea Surface Temperatures NCEP
MEMPHIS, TN (WMC) - Before we can look forward, we have to look back. How did our winter compare to past winters? Winter weather dominated our forecasts during the first two months of 2015. We saw our fair share of sleet, snow and ice in the Mid-South and it happened multiple times. You could say it was an above average winter regarding the number of times we dealt with frozen precipitation. As far as amounts go, it certainly wasn't the most. But it was enough to cause travel issues. Regardless, we saw below average temperatures the first part of January and much of February.  

One thing we haven't had to worry about is severe weather. It's been a below average year to this point across much of the U.S. in regards to number of tornadoes and even warnings. Typically, Memphis has at least some non-severe thunderstorms, but we haven't…yet! Looks like we may get our first shot at some weakening storms Wednesday night. For now, the severe threat should remain to our northwest.

The big question as we head into the spring: will we have more or less severe weather through the end of May? This quiet pattern may continue or at least we may not see many “major” severe weather events. Two major factors support this idea. First, the jet stream has been dipping much further south over the eastern half of the country creating what we call a “trough”. That has been the pattern much of the winter and part of the reason we have had wintry mess in the south and record-breaking snow in the northeast.

The other reason has to do with El Niño. NOAA has confirmed a weak El Niño has been detected. You may be wondering what that is and what it means for the Mid-South. I attached an image of sea surface temperatures along the equator. Find the pacific ocean and notice the how warm the temperatures are along the 0º line. They are usually fairly warm but NOAA monitors any minor or major changes. When it cools significantly, it signifies a La Niña. Here is how NOAA defines it.

“El Niño is characterized by unusually warm ocean temperatures in the Equatorial Pacific, as opposed to La Niña, which characterized by unusually cold ocean temperatures in the Equatorial Pacific. El Niño is an oscillation of the ocean-atmosphere system in the tropical Pacific having important consequences for weather around the globe.”

Basically, a strong El Niño can greatly impact the position of the jet stream and areas of high and low pressure. Due to the expected weak strength, widespread global impacts are not expected. However, we may see certain impacts often associated with El Niño this spring. Those impacts include cooler temperatures and wetter conditions. That typically reduces our severe weather threat. That DOES NOT mean we can't see a major tornado outbreak. It just means the chances are somewhat reduced. And since this is a weak El Niño, it's still up in the air. The long range forecast models (10-14 days out) are not showing signs of anything major, but there will be one or two rounds of storms that bear watching. For now, we will wait and see how it pans out. 

Spencer Denton
Noon and 4 PM Meteorologist
Twitter: @sdentonwx
WMC Action News 5 Storm Tracking Team

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