Now that we’ve flipped the calendar to November, some, or maybe many, are turning towards winter.
As I start thinking about what this winter may bring to the region I look at many different things… One of which this coming season may or may not have an out-sized affect on our general winter weather pattern…and that is El Nino.
El Nino is a warming of the equatorial Pacific Ocean waters, typically from the coast of western South America westward. The amount of warm water in scope and warmth determines the “strength” of El Nino. Some El Nino’s are weak, some moderate, and some strong.
These categories can affect the jet stream patterns around the Northern Hemisphere, and IF that happens, then that in turn can affect us at some point.
We’ll dive into all this in a minute, and this will be the 1st of 2 blogs I think, the other coming on Friday…that dives into El Nino.
One sentence forecast: After a cold start this morning… We moderate a bit this afternoon with blustery winds taking the edge of the moderation as highs climb into the upper 40s
Today: Sunny and increasingly breezy in the afternoon, with highs in the upper 40s. Winds may gust around 25 MPH later today.
Tonight: Not as cold with lows near 32° and may actually go up a few degrees overnight
Tomorrow: Sunny and warmer… Highs in the mid to upper 50s
Friday: Windy and warmer with highs in the mid 60s
No real significant weather for awhile…perhaps a weak rain system next Monday or so…moderating temperatures with 60s coming Friday into the weekend.
So let’s get back to the title of the blog.
I’ve written about El Nino (warming) and La Nina (cooling) dozens of times over the past 20+ years of the blog.
So let’s review:
What is El Nino?
As mentioned it’s a warming of the equatorial Pacific Ocean waters. When looking for El Nino…we look at the Pacific Ocean and look towards the equator. The chart below shows ocean water temperature anomalies.
The area that I’ve outlined in blue…show MUCH warmer than average temperatures percolating from South America to south of Hawaii to northeast of Australia. The temperature anomalies, in this case the warmer red colors and broad and dramatic.
Of note…also look at how much of the world’s oceans are red…there’s some blue in there indicating cooler than average temperatures but there is a LOT of red shading around the world!
The transition from La Nina (cooling of those same outlined waters) to El Nino started roughly last January and accelerated in the early Spring as they spread westwards. We actually break the equatorial Pacific down into 4 regions to help us determine where the El Nino is strongest and weakest.
The area that we typically watch the most is the area called Nino 3.4 and over the last month or so…the anomalies have strengthened in that general area and especially westwards towards the Dateline (180°) on the chart below.
Why is all of this important?
What happens in many cases, especially when El Nino or La Nina is moderate to strong…is that this heat (in the case of El Nino) affects the weather circulation patterns across the hemisphere. This happens because heat is being released from the Ocean into the upper atmosphere above through a variety of processes and this in turn helps to create stronger upper air flow out of the tropics and towards the poles. This, while simplified, alters jet stream patterns.
At times that has effects through the hemisphere and into the United States.
How strong is this El Nino compared to others?
This is still being figured out because there are guidelines used for determining this information. The maps that I showed above are pretty much snapshots in time. To determine the “strength” of El Nino we look at 3 month trends. IF you have 5 consecutive 3 month trends where the waters are running at least 1/2°C…it’s an El Nino. Then we break it down more for strength. If only 1/2° above average…it’s weak…if above 1° it’s moderate and above 1.5° it’s strong…and above 2° that’s very strong. That time frame is 3 straight 3 month chunks. Typically this is done by season.
Right now we’ve had 2 3 month chunks of El Nino into the “strong” category.
You can see from the chart above that recent strong or very strong El Ninos have happened in 1991-92…and 1997-98 and 2015-16 (very strong).
Based on the data so far…and model forecasts…this will likely settle in to a strong category El Nino.
So what does history tell us about these particular years regarding KC snow?
I’ve highlighted the snow totals in the years concerned. Average is around 18″ now for a snow season.
That 2015-16 year certainly sticks out like a sore thumb.
So easy peasy right? Well no!
Each El Nino does different things…and it’s ONLY 1 PIECE of the atmospheric puzzle that needs to be looked at. So many other things are out there that need to be recognized if nothing else.
One is the location during the winter of the strongest temperature anomalies in the El Nino region. There is some thought (and we may be seeing this develop now) that the better anomalies will be trending westwards as we go through the winter. IF this happens then we refer to this type of El Nino as El Nino Modiki. Previous Modiki events have been in 1991-92, 1994–95, 2002–03, 2004–05, and 2009-10
Of those 5…and referring back to the total snows in the above chart…4/5 were pretty bad snow total winters for this area. There is an exception though…2009-10…in case you didn’t look back up…that was an EPIC winter here…close to 45″ with numerous thundersnow events. It was a snow lovers dream come true.
Can that happen again? It would take a lot…and perfect storm tracks and enough cold air…and enough gulf moisture…and enough dynamically strong set-ups…you know almost all the things that we haven’t had recently…lol.
More on El Nino in Friday’s blog.
The feature photo is from Cathy Wendte