Another Reason to Use Seasonal Predictions with Caution

If you've been following weather trends this fall, you may have heard that an El Nino weather pattern will steer our weather patterns this winter. El Nino is a warming of water in the eastern Pacific, which in turn redirects some global weather patterns. This often leads to more active weather in the western and southern U.S. during winter.

Notice the word "often". Certain overriding weather patterns can take hold, but natural variability can make a mess of those patterns, making those predictions about what will happen this winter a little less cut-and-dried.

The former Hurricane Ida is a prime example. A November storm in the Gulf is relatively rare; a storm in the Gulf in an El Nino year is even more unusual, as El Nino patterns tend to stifle the growth of tropical systems. "Wisdom" says that storm never should have developed as it did...yet we had a Cat 2 hurricane at one point before the storm weakened.

"Wisdom" from some sources tells us that we we are in for a rough winter. More than a couple of forecasters out there have gone on record saying that we will have a rough winter, packed with cold and wet weather that will yield snow and ice. At the same time, the National Weather Service's seasonal forecast has our temperatures running below-normal, but our precipitation near-normal...that's a forecast that doesn't quite indicate a "wet" winter.

So who's right? Both forecasts have some validity. A colder season can increase the likelihood of snow and ice when we do get precipitation. Conversely, 40 degrees and rain is also wet and below-normal, but it does not mean snow and ice. So we can be cold and wet without it being filled with nasty winter storms.

Also, how much precipitation will there be? If the weather is really active just to our south, that can rob us of moisture, limiting our potential. If that active weather marches north, we get more moisture...but we also warm up a bit. Unless...the infamous cold-air wedge builds in! That's our typical, ice-creating weather pattern where cold, dry air builds in from the northeast, sometimes turning rain into ice during winter. To really cause problems, this usually requires cold high pressure to be anchored over the Northeast. So I would be more concerned if I saw forecasts calling for an unusually cold winter in the Northeast...that would create an avenue by which that cold air could rush down the eastern slopes of the mountains and spend a lot of time over us. The current outlooks are for "normal" conditions in the Northeast this winter...meaning we're no more likely to get a full-blown wedge than we are in a typical winter.

It will all come down to timing; we'll have wet stretches and we'll have cold snaps. How often will those two elements come together?

There's a lot of natural variability that has yet to occur; this will determine the answer to the above question. This variability dealt us a large, March snowstorm last season; it will determine the number and strength of any storms this year. Hurricane Ida "shouldn't" have happened in an El Nino year, showing it's possible that something else may await us that "shouldn't" happen in an El Nino year.

By the way, in case you haven't figured it out...I'm not a large fan of seaonal forecasts...