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What does the pattern change mean?
Good morning, It's FRIDAY!
I am one of the judges at the Elvis parade today. It is downtown at noon on the Barney "Elvis" Plaza, right across from the Marriott hotel. Come on down and get there by 11:30 or so. The parade begins at 12:05 PM.
Now onto the pattern! If you are a regular reader of this blog then you know I talk about the weather pattern and how it develops, cycles, and falls apart. I have a theory of which we are always working on: "The weather pattern sets up between October 10th and November 10th. It then begins cycling. This cycle is undefined until it begins repeating. Usually by mid December or early January at the latest the pattern is repeating and then the cycle is defined. The pattern continues until it falls apart in late July or early August". This is my theory of which we are convinced happens every year. I have been keeping track of this since the late 1980s when I discovered it. And, the past few years I have all of the data that shows the evidence. I presented this theory in Washington D.C. last August at the Broadcast Conferenece for the A.M.S.
One part of the theory is that it falls apart around this time of the year. And, it just fell apart. And, I believe what has been the "same" pattern since last October and early November no longer exists. It literally in the process of dying right now and by Sunday I think it is gone. There isn't a trace of it left. The past few weeks as I have looked for its demise I thought it was falling apart two or three other times, but this time it is obvious. There were some unique characteristics to this pattern that began 10 months ago. One of which has been a mean "long term" long wave ridge extending from Montana north into Canada. This feature is the main reason why we have had a hot summer, a dry year, and a very frustrating pattern. If there is a strong mean ridge near Montana and it extends north from there then storm systems have very little chance of intensifying as they approach us, which is what we want in an exciting pattern. Instead storm systems go through that ridge and then are nothing as they move into the plains. This ridge has been one of the main features. It isn't always there, but it has been there for about 60 to 70% of this cycling pattern that was about 60 days for each cycle which has repeated many times since the first cycle completed in December. The other 30 to 40% of the pattern was somewhat more interesting as that ridge was in a weakened state.
This Montana northward ridge is also the reason for our heat waves. As summer has progressed the heat would build downstream of this mean ridge over the Dakotas and then spread in from the northwest, back to the west and then make another run at us from the Rockies. This has now happened several times and is the reason South Dakota has had near 120 degree heat a few times.
So, I believe the pattern is gone by Sunday. What does this mean? It may still be hard to notice at times since it is still August. And, depending on what this transition pattern is, we will be susceptable to different set ups for heat. Another heat wave is not out of the question. At the same time, some of the frustrations with the lack of rain and lack of excitement with thunderstorms may be relieved. Sunday night and Monday will be our first test. Let's see how the rain patterns set up through our region. Oh, it still is August and it may be tough, but something different will happen.
Below is the 168 hour 500 mb flow from last night's GFS run. The deep trough in the west from the north pole on down is so different than anything we have seen with the last pattern. But, since the main jet stream is still north, as it should be at this time of year, it will likely still be hot.
Click to enlarge (500 mb flow one week from today)
There are so many things different about the pattern beginning in the next two days. This "in between" pattern is going to be in chaotic flow until early to mid October when a new pattern evolves and begins cycling. I can't imagine a worse pattern than the one we just experienced and we are so overdue for an exciting pattern. Can you imagine a normal winter with average snowfall. Average snowfall is around 20 inches (100 year average). That would seem like a lot of snow.
Have a great weekend.
Gary
Posted by at August 11, 2006 7:47 AM
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Hi Gary:
You know, I was thinking about your forecast yesterday. Ok, so you were of a few degrees. The more I read your bogs, the more I start to understand how complex weather really is. Your job is to estimate or calculate in advance, especially to predict and give us analysis of meteorological data right? Then you come up with something based on what you believe to be true.
Belief is essentially a subjective feeling about the validity of an idea or set of facts. It is more than a mere suspicion and less than concrete knowledge. Unlike suspicion, which is based primarily on inner personal conviction, belief is founded upon assurance gained by empirical evidence and from other people. Positive knowledge, as contrasted with belief, is the clear perception of existing facts. Belief has been defined as having faith in an idea or formulating a conclusion as the result of considering information.
Then, your forecast becomes a justified belief, which is one which we are within your rights in holding. By this is meant, not political rights, or moral rights, but "intellectual" rights. In some way each of us is responsible for what we believe. We don't just go off and believe anything. We each have an intellectual responsibility or obligation, to believe what is true and to avoid believing what is false. When you look at all your data, you believe that data to be true based on your knowledge, education and experience. The thing is, being intellectually responsible involves being within one's intellectual rights in believing something; in such cases one is justified in one's belief. Now, I realize that is kind of deep, but the bottom line is weather is not an exact science. There are still things that we do not completely understand.
I was kind of bummed we did not get more rain. The thing is you have done a very good job coming up with a group of facts to make predictions about the weather. I think your theory should be taken seriously, and perhaps studied even further. Maybe you could get a PhD in meteorology and the dissertation could be on your weather theory! Anyway, happy forecasting!
Brian - From Overland Park
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Brian,
Great analysis and deep thinking this morning. Forecasting the weather is rather difficult but as I read your thoughts it really came together for me. And, it is the experience, understanding, and ability to then translate it into a weather forecast that makes us the forecasters we are. O.K., now I am getting to much into your thoughts. Yesterday was a very strange day. As of 7:45 to 8 AM I was still convinced we would be near 106, shoot it was 103 the day before. But, a few things unexpectedly happened.
Have a great weekend.
Gary
Posted by: Brian at August 11, 2006 7:53 AM
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Gary, we just had .45inches of rain and it's still raining here in N. Grain Valley...what an odd thunderstorm.
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Chris,
WOW! Thank you for blogging this morning. I just looked at radar and I see that rather strange thunderstorm. It was right over Grain Valley. It is isolated and the only one. If you hadn't blogged, I wouldn't have seen it. Unreal.
Thanks for the report.
Gary
Posted by: Chris at August 11, 2006 8:16 AM
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Ok..Gary, per your last entry back to me, I took another look at Sunday. [Got off the showing off blog, and wanted to reverify]
I looked at the 200, 500, 850, and MSLP. I don't think the 850s will support the heat you still think. [my opinion]. Sunday is a set up before a cold front, thus compression heating is possible. I don't think the front will be close enough to compress that much. Rain looks like it will still be north of us, and the dewpoints should be high. I do see the ridge nosing up to KC south of us, but looks pretty weak to me.
Long story short..based on the info I can see, and intrepret, and gut feeling. I am still going with 92 on Sunday with rain coming Mon/Tues.
In the GRC this year, was the Montana ridge the predominant feature you were watching to make this unique?
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Scott,
The GRC was unique in every single fiber of its existence. The eastern Pacific "Storm Generator" (I called it that in November when we issued the winter forecast) was a very dominant feature, the Montana northward ridge, etc. But, there is so much more to the 60 day cycle. During the cycle there are phases where you wouldn't even know there was a Montana ridge. This is the most amazing part, but the ridge would pop back up in various forms right on schedule. Next year the cycle could be anything from 20 to 80 days. We just won't know and this part of the theory is still a work in progress. You will see it with us this fall. It is frustrating waiting until the cycle repeats. But, you can make a very educated guess at where the main features are located by November 5th to 10th.
Now to your forecast of 92 on Sunday. I will likely be sticking with 97 degrees. The front is approaching and 850 temperatures will be supportive of upper 90s, if the NAM is correct 101 is possible. So, we will see. But, with the changing pattern it is looking a bit different with every model run. Good luck.
Gary
Posted by: Scott at August 11, 2006 9:14 AM
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Gary,
I appreciate the job you and your staff do. It is exceptional. As I said to somebody yesterday, predicting the weather has an infinite number of variables, many of which you can't see, which makes it exceptionally difficult.
And yes, I can dream of a "normal" snowfall. However, being from New England, that includes at least one 20-inch snowstorm (not winter) and about 60-plus for the year. It would be great. Now if we could teach MODOT that putting salt down first leads to ice, we would be much better off when it comes to driving.
Keep up the good work!
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Matt,
A 60 inch snow season would be dreamy to me. I did experience 57 inches of snow in four days while visiting Lake Tahoe a few years ago. I left during the storm a day early so I wouldn't miss a Kansas City storm. Well, the KC storm went north and I came back to nothing but drizzle.
Gary
Posted by: Matt at August 11, 2006 9:58 AM
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Gary,
This is just a general weather question...On one of your recent weathercasts, you pointed out an outflow boundary on ESP that was moving from east to west. You commented that it (the boundary) could spark more thunderstorms if it made it further west. How do you differentiate between an outflow boundary and a dry line? Don't they look similar on radar? Does it have to do with the current atmospheric conditions?
TJ
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TJ,
Each boundary may look similar on radar, but more importantly how was the line created? The other day when I showed you the outflow boundary we tracked it and new that it was formed by the thunderstorms and the cool "outflow" from the thunderstorms was spreading west away from the activity. This leading edge was bumping into the moisture and kicking off more thunderstorms.
A dry line is created more dynamically and is much larger scale and is there whether there are thunderstorms or not. A dry line is simply a trough of low pressure where there is a wind shift. There are no temperature differences near the dry line during the day and thus it is not a front. A front is also a trough of low pressure, it just happens to have either a colder or warmer air mass behind it.
Have a great weekend. I hope this helps.
Gary
Posted by: TJ at August 11, 2006 10:30 AM
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