I've had a little bit of time to do some analysis on this developing weather pattern. But in reality the more I look, the more conflicting signals I get! I have a lot to discuss and hopefully I can make some sense of this mess.
Starting with ENSO (essentially El Nino and La Nina). Do you recall the outlook from the "experts) last fall of the Godzilla of all El Nino's bringing massive and flooding rains to California? It DID NOT happen! I for one was not surprised. Go back and read those posts if you have time. You see, it's just not El Nino or the sister La Nina that create or control our weather.
Fast forward to the present. You might have heard that we're in for a weak La Nina (cooling of the equatorial Pacific waters). Based on that, the Climate Prediction Center (the experts) came out with a forecast on the 20th. I did a quick post on that and you can read it here. The CPC went with a composite forecast based on La Nina. What that means is taking an average of weather during a bunch of La Nina's (without regard to strength and location) and posting that as a probabilistic forecast. It might work for a small percentage of the country but that is it (if El Nino or La Nina dominate the forcing)!
It's ironic that the general upper level flow the past 2 to 3 weeks has actually been more what we see during an El Nino! In other words the atmosphere is responding and behaving like the forcing from the tropics across the Pacific is in control. Will that last? Nobody knows. But, what is VERY interesting to me is that the Southern Oscillation Index (measurement of the state of the atmosphere across the Tropics) has crashed in the past few days. The numerical index is as low as it has been since early June when we were still in the El Nino regime! This really boosts my confidence that there may NOT be a La Nina this winter, rather it should stay in a neutral phase. So, I'm somewhat confident that the tropical Pacific will not be the main influence this winter.
Before I move on, as many of you know there was a weak system that came through earlier this week. Some areas got "lucky" and got some much needed rain. Unfortunately for most of us we got zilch. Here is the map of precipitation:
For the past week you may have seen some optimistic forecasts from the NWS and others about an increased chance for rainfall later next week. Computer models have been all over the place. One will be wet, then dry, then wet, etc. Although there "could" be something around the 2nd-5th time frame, I have zero confidence in anything at all. There are systems, but the flow is going to have to transition soon, or it won't happen. Here is an optimistic outlook from the Weather Prediction Center (I hope it verifies but don't count on it):
We're desperately going to need something soon. With this ridiculously warm October, the soil moisture is depleting rapidly. Here is the latest U.S. Drought Monitor:
Back to the October temperatures...
At the Dodge City airport, this October should end up as the 3rd warmest on record (back to 1874). Right now we are on pace to set an all-time record for the warmest Fall (Sep-Nov) if things don't change soon. Also, some areas have not had more than a quarter inch of rain since late August. If you go back to earlier posts I did this summer, this was expected (especially the September into October).
Looking ahead:
If you have been following this blog (started April 15, 2014) for a while you know that I have several posts about how the pattern establishes during the fall and then cycles or repeats for the next 10-11 months. Often the cycle length is around 40 to 50 days but can be much shorter or even longer. Since the formation doesn't even begin until around October 1, it is impossible to predict the cycle length until the first obvious repeating begins. This "new" pattern is only 3 to 4 weeks old.
The initial formation of the pattern may be influenced (by varying amounts) from many different forcing mechanisms. One is from the equatorial Pacific area. Another from the northern Pacific. Others from the Arctic region, northern Atlantic, landmass/ocean interactions, perhaps the huge northern Asia continent, solar output, etc. How each of these contribute or interact with each other would be a lifetime of research.
I don't like to jump to conclusions in October, but so far I'm a little concerned. I would have liked to have seen a storm or two develop into the southwest U.S., but so far that has not been the case. Yes, there have been a few minor systems that brought SOME areas rainfall but nothing widespread. There have been quite a few frontal passages, but without cold air since that source has been bottled up near the north pole or particularly across the northern Asian continent.
Now if you want to search the internet, there are already a lot of outlooks out there. Here are four of them:
Quite a difference! Are any of them correct? Quite possibly! But what are they based on?
Like I said earlier in this post, there are conflicting signals (without taking into account that I'm waiting for this initial weather pattern to cycle). In no particular order....
First, most of the cold air so far this Fall has been bottled up over the pole or Asia. Here is the current snow cover for North America: (It is actually a little less than last year at this time)
Something I look at regularly is the Arctic Oscillation (AO) which takes into account surface pressures across the Arctic region. When pressures get high cold air is dislodged towards the equator, and much of the time into the continental U.S. When the AO has a negative value those pressures are climatologically high. This fall, so far, much of the cold air has dislodged into Siberia and not the states. The AO has been strongly negative so far and is forecast to be that way for much of the time into January. Eventually the cold air that builds up will also come into the U.S., or at least should.
Another index I look at is the North Atlantic Oscillation. This looks at the pressures from Greenland into the north Atlantic. When this index goes negative the upper flow tends to buckle and allow cold air to sweep south into the U.S.. So far this index reading has been forecast to lower after a very recent spike.
Looking at the ocean temperature anomalies.
Three forcing areas from the Oceans that I think contribute to the pattern are the ENSO region, the North Pacific and the North Atlantic.
For ENSO:
There has been a cooling of the equatorial Pacific but not quite long enough or cold enough to be a full fledged La Nina (and may not be based on some ideas):
For the Pacific Decadal Oscillation:
The index has cashed to near neutral.
For the AMO:
There is a blob of colder than average water across the north Atlantic.
All three areas may influence the pattern (or have already).
Another item that has caught my attention is the anomalously warm water in the Gulf Of Mexico. This would be a great source of moisture for any storm that could get going later this fall or winter.
I would think the threat of tornadoes across the deep south and perhaps up the Lower Mississippi Valley would surely be higher than normal. Maybe into Oklahoma and eastern KS?
I've already established that I don't like making outlooks this early since the pattern just started to develop and hasn't cycled yet. So, at this point I can only go on some climate history or I could just make a big WAG!
For the Winter months (December, January, February), look at this from Dodge City:
Since 1998/99, the average temperature for the three month period has been trending colder. The past two winters had above normal temperatures. Can it be three in a row or do you think it would be colder based on this trend? I say based solely on this colder (at least at the normal value). But does this fit the atmospheric forcing? Maybe, maybe not.
Looking at the index value for ENSO and of the PDO (discussed above), the only two times on record that I can find that represent a similar phase and progression of ENSO and PDO are 1995 into 1996 and 1959 into 1960. The best fit was the 1959/1960 winter (based on the indices) and second best was 95/96.
I did a little figuring using a dry October and a warm October for Dodge City. Out of the top 20 warmest Octobers, the follow winter was dry 10 times, wetter than average 4 times and the remainder near average. The following winter was warmer than average only six times, colder than average 7 times and near normal the rest.
For the top driest Octobers, the following winter was drier than normal 13 times, wetter three and normal 4. For temperatures the following winter was warmer than average 6 times, colder 7 times and normal the rest.
Taking into account both the top warmest AND driest winters yields about the same. Well, that really doesn't help, does it? The only thing that stands out is that the top three warmest and driest Octobers were followed by above average temperatures for the winter, but one dry, one normal and one wet. Geez.
Back to the 1995/96 and 1959/60 ENSO transitions. October of 1995 was colder than average, but 1959 was above (but not top 20). October of 1995 was the 8th driest on record (only 0.08" at Dodge City). October 1959 was wet recording 3.30" of precipitation. Geez.
I think what I'm pointing out is that making predictions based solely on what happens during the fall is pointless. I've got to know what the pattern is doing and how it will start to cycle or repeat.
If you want a guess at stage in the game (without the first completed cycle)...
It appears more than likely that this dry pattern will persist into November and honestly I'm not feeling really good about anything changing for a while. That is being pessimistic but all the while that there are actually a few systems that "could" bring a brief change. Let's hope and pray.
The first widespread killing freeze is still a week or more away. Overall on average, temperatures will likely remain above normal through much of November. But, there will be a couple of strong pushes of cold air, especially by the middle of the month.
For the winter months of December, January, and February. My guess is that temperatures will average out around normal. But there will likely be some really cold periods (highs in the single digits, lows 5 to 15 below across western KS). These periods will be offset by several really mild periods too! Deep penetrating bitter cold into west Texas is likely a couple of times.
Optimistically precipitation will be near average (normal to above on snowfall).
Since the cycle of the pattern hasn't repeated, I can't give much on the forecast for the spring and summer (at this time). Looking at yearly precipitation
A couple of above average years are typically followed by below average rainfall (there have been exceptions, especially in the 70s and 80s). I've been expecting 2017 to be below anyway (based on long term trends and cycles). I hope it is closer to average. But don't put too much stock in that yet until the cycle of the pattern is established.
I've got more coming up on my plate so I won't be able to update this blog until about the 7th or 8th.
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