Well once again it’s time for the 2015-16 winter forecast. I’ve promised myself I’m going to try to keep this at roughly 1500 words which would be 50% shorter than the missive I wrote last year…let’s see how I do. For those who don’t want to read my more technical discussion…scroll down towards the bottom of the blog for the actual numbers.
Forecasting the weather and then talking about the whys of the forecast is obviously my passion. I think you know that after having watched FOX 4 all these years with me (20 years and counting). Forecasting seasonal weather though weeks ahead of time has never really been a strong suit of mine personally. All of us try to get an idea of what could happen, but when the forecast is tough to do 5-7 days out…it’s really next to impossible to do with any true accuracy, despite what any entity (government or otherwise) may claim, over the course of 90-120 days out…which is what we’re attempting to do here. There is guidance that is looked at often, including long range forecast models…but often they’re terribly wrong.
So where does that leave us this morning? Well this has always been one of the biggest questions we get during this time of the year…what will the winter be like? So in response to overwhelming demand…her goes.
One of the things that you probably have heard so much about is El Nino. It certainly when on the strong side especially can have a strong influence on the weather in the USA. See this blog for additional details on what El Nino is and what it does to the weather patterns. In a nutshel, it’s a warming, to various extents, in the tropical Pacific near the equator on our side of the hemisphere. This is what El Nino looks like…
The extent of El Nino, or how large it is, is looked at by looking at the Nino regions…which are numbered from 1-4…typically there is a region that is looked at harder than others called 3.4 which is a combination of 2 regions.
All the regions interplay with each other…and to some extent, when especially strong, can influence the weather patterns across the hemisphere and here in the USA.
There are other ways that we look at these warming areas…but it’s important to note that we need to physically see a connection with the atmosphere to see how El Nino is changing things up. That connection is measured by other indices that are often looked at by meteorologists and in a more understandable way…we see certain jetstream configurations that tell us that the odds of El Nino influencing the atmosphere are higher.
It’s also VERY important to note that not all El Ninos are the same. The vary in strength (how much above normal the water temperatures are) and size…where are the strongest warm anomalies located…are they closer to the South America coastline or farther west towards the Dateline area (180° west longitude). In this case…they’re more centered near 100-160° west or in the Nino 3.4 vicinity. Again this may provide hints about the future.
These warm area locations…help to provide more heat and moisture into the atmosphere above…thereby setting up feedbacks into the atmosphere altering weather patterns. The graphic below is from WSI.
These feedbacks then can be averaged out over the course of many El Nino’s are a approximate forecast can be made from it…about how the atmosphere responds to El Nino conditions. Again this is a typical forecast for EVERY El Nino it seems and this year the NOAA forecasts are very close to the map below.
So just by looking at the forecasts above…for KC you can see we’re on the edge of having higher probabilities of warmer than average temperatures and wetter than average precipitation conditions.
Interestingly IF you look at the strong to very strong El Ninos over the course of the last 60+ years…we find 5 of them. 1957-58/1965-66/1972-73/1982-83/1997-98. Now lets take all those years and average them together and see what you get for temperatures across the USA…
The greens and yellow represent the warmer temperatures compared to average while the blues and purples represent the colder averages.
Now for precipitation which is total rain and melted snowfall totals…
Again those are the averages over the 5 strong to very strong El Nino winters…defined by December to February.
Notice CA and the deep south through the SE part of the country does well with moisture…while it typically runs cooler than average. The northern US, especially the upper Midwest and northern Rockies are strongly in the warmer category…really most areas from roughly the I-70 corridor northwards.
So since almost all of you want to know about the snowfall…let’s look at the snowfall numbers from these strong El Nino winters (all 5 of them) and for that I’ll be using the FOX 4 Weather Almanac which is a great resource for previous KC weather if you need information about what the weather was like on a certain date and snow/rain stats over the months/years in KC.
You might think with the warmer temperatures in the maps above that that would be trouble for snow lovers…well you would be mostly mistaken…considering the average snow for a winter is around 19″…here is what the data shows…
Winter of 57-58: 31.2″
Winter of 65-66: 9.7″
Winter of 72-73: 19.2″
Winter of 1982-83: 23.4″ (very strong El Nino)
Winter of 1997-98: 19.6″ (very strong El Nino)
From a snow standpoint…4/5 winters were OK to good for snow lovers. So El Nino is NOT necessarily the death of snow storms in the KC area. Interestingly…if we look at the two strongest previous El Nino’s for temperatures here in KC…the 82-83 El Nino may have given us the 33rd warmest DEC>FEB period and the 97-98 one may have given us the 8th warmest winter in KC weather books. With the exception of the winter of 72-73 the other El Nino winters were also warmer…the 65-66 El Nino was the 15th warmest.
El Nino is still thriving and by some measurements it’s one of the, if not the, strongest on record. Other previous strong El Ninos were in 1997-98 and 1982-83.
The two stronger El Nino winters also gave us 3 snow events (DEC>MAR) that had at least 3 different 3″ of snow “storms”…so there were definitely snowstorms in a sea of warm temperatures over the course of winter
Another point to be made…ALL El Nino’s regardless of intensity are NOT the same…one important variance as I mentioned is where the warmest waters are located. This means their effects on the weather over the course of several+ months can vary. For example…the last time El Nino was at least this strong, if not stronger, was during November of 1997. Here are how temperature anomalies fared that month nationwide…
Look at those below average temperatures…from the Rockies eastwards…
Now look at the temperature trends this November…
I think that would be the TOTAL opposite!
So before I hang my hat on El Nino…one has to remember that other things are happening in the atmosphere, in the big picture at least aside from JUST El Nino. The rainfall trends are a little more connected in the SE part of the country, at least, when when compare the 2 Novembers above.
So as mentioned there are other considerations to all this as well…but again I’m trying to keep this under 1500 words (and failing) for you this year…but some of the other considerations include observing this other area of the Pacific Ocean which, much like the last couple of winters is still rather warm compared to average…click on the image below to make it more readable.
You’ve probably also heard of “the blob” which is that area of warm water in the northern Pacific Ocean near the Gulf Of Alaska…that’s been around for a couple of years (although it seems like it’s diminishing somewhat lately). These areas of warmer waters also “feedback”into the atmosphere. There are correlations to “the blob” helping to promote an area of upper level high pressure which alters the jetstream meaning warm/dry conditions in western Canada but NW flow here at times…then there is that cold “blob” of water in the northern Atlantic which could promote dips in the jetstream…bringing colder conditions at times to areas out east, especially towards the eastern seaboard.
A lot of folks also concern themselves with “blocking” or the tendency of weather patterns to be “locked in” for more than a few days…i.e. cold shots of air that repeatedly come down through parts of the country over the course of several weeks let’s say. This is somewhat measured by looking at other indices called the Arctic Oscillation (AO) and the North Atlantic Oscillation (NAO). Some consider this stuff to be the end all be all when it comes to winter weather forecasting. These indices aren’t. We can get plenty cold with no “blocking” in the atmosphere however it’s tougher in my opinion to “sustain” that cold weather. When the AO/NAO are raging positive…blocking is tough to get…then raging negative…it’s MUCH easier to get sustained cold. My suspicion is that this winter, more often than not…blocking in the atmosphere relating to weather in the states will be tougher to achieve…leading to periodic but NOT necessarily long lasting cold shots.
Another important point to the above paragraph…and we’re seeing it play out for the rest of November…just because we don’t get these ideal Arctic type shots of cold air…doesn’t mean we cant get “USA” manufactured cold (combo of US and southern Canada). By this I mean systems like the one we’re seeing over the next 3-4 days…wallowing around underneath the main jetstream which will be diverted well north of the USA at times. These will leave a trail of cold that because of clouds…may create cold days…but those same clouds keep the temperatures from falling overnight. Something else to watch for in the winter play out.
El Nino also correlates very well with a stronger sub-tropical jetstream…this is what helps to bring what we refer to as “split flow” to the United States, especially out west. This is an example image of split flow from weatherunderground.
That split flow brings a lot of mild moisture from the Pacific into CA and the SW part of the country. Those storms may have a tendency to “mostly” pass to the south of the area…however there are going to be some close calls and as we’ve seen late this fall…getting rain has not been a problem in the last couple of weeks. All it takes is one storm to take the right path and boom you get 4-8″ of heavy wet snow, if not more…I can’t discount this chance. My question is are we looking at more rain changing snow events since overall I feel the atmosphere will have a milder bias through the winter months but by the same token have more available moisture for whatever storms we get to work with.
OK so I’m up to about 1500 words now…below are the winter forecasts from each of us…snow total at KCI then the coldest temperature where expecting for the winter season and a brief bullet point hit on potential highlights of the winter…1st up is Karli…
Here is Mike’s…
and finally mine (oh and I still hate that picture :) )
this gives us our team average…
So overall we’re expecting slightly below average winter snowfall.
I, personally, still think the winter overall will be above average in temperatures and above average in moisture. I think long-lasting cold weather will be tougher to achieve…I overall think there will be times where we’re wondering what happened to winter…as stretches of “milder” days (compared to average) will be impressive. I think JAN>FEB will offer the better chances (more often) of snow accumulations. I side with milder than average temperatures for December at least.
That’s it…I went over my self-allotment of 1500 words by about 350…so overall that’s pretty good (for me at least :) )