I suspect admin was not all that enthusiastic about publishing this particular piece: http://www.firsttracksonline.com/2015/0 ... r-winters/
But I was quite entertained by this excerpt:
But I was quite entertained by this excerpt:
An Amusing Anecdote from FTO News Article
- Thread starter Tony Crocker
- Start date
Some Utah locals claim mid-January is more likely to be dry than other times of the winter. Concrete evidence has yet to be presented in support of this assertion.
When, other than anecdotal comments during January dry spells? No comparison has been made to other winter months other than what I'm now presenting here for the third time.Marc_C":11a194bm said:
This is the list of consecutive days of no snow within 31-day winter months at Alta over the past 11 seasons:
Month 1: 11,10,9,9,8,8,8,6,5,5,5,4,4,4,4,4,3
Month 2: 11,9,8,8,7,7,6,6,6,5,5,4,4,4,4,4,4,3,3,3,3
Month 3: 12,11,10,9,9,8,7,6,5,5,5,4,4,4,3,3,3,3
This time I've not labelled which month is December, January or March because I defy anyone to find meaningful differences among the above three lists.
The previous times I've shown these series there has been no response, other than to drone on about
Which at this point can best be characterized as
Marc_C
Active member
I'm not going to rehash it. Your insistence on not doing the proper statistics* makes it pointless, as does your constant reframing of what we (the locals) actually said. Believe whatever you think your precious arithmetic averages are saying (a classic case of the [over]use of averages essentially eliminating the observed anomaly) and ignore the locals who experience it year after year.
*: I agree it's a PITA to calculate this one which is why I sure don't want to do it! I also no longer remember enough of advanced stats and calculus.
*: I agree it's a PITA to calculate this one which is why I sure don't want to do it! I also no longer remember enough of advanced stats and calculus.
digaaron, see what you started? 
I had intentionally ignored the original post.
In a nutshell, based on personal observations from those of us who actually live here, nearly all of the Utah locals on this forum have concluded that we regularly see a dry high pressure and accompanying temperature inversion sometime around mid- to late January, give or take a week or two. Furiously crunching averages late at night from a computer hundreds of miles away somewhere in the Los Angeles Basin, Mr. Crocker believes that his statistics dispel that notion.
It's one of the longest-running pissing matches on this forum. Its ugly head reappears about every six months or so, "on average."
I had intentionally ignored the original post.In a nutshell, based on personal observations from those of us who actually live here, nearly all of the Utah locals on this forum have concluded that we regularly see a dry high pressure and accompanying temperature inversion sometime around mid- to late January, give or take a week or two. Furiously crunching averages late at night from a computer hundreds of miles away somewhere in the Los Angeles Basin, Mr. Crocker believes that his statistics dispel that notion.
It's one of the longest-running pissing matches on this forum. Its ugly head reappears about every six months or so, "on average."
oh man, I had no idea I was reigniting such a heated debate.
I'm actually a writer who just finished a story on climate change and skiing, with an emphasis on the work of Protect Our Winters, which was why this post originally piqued my interest. I figured if a fiery conversation was going to happen it would be on that topic.
I'm actually a writer who just finished a story on climate change and skiing, with an emphasis on the work of Protect Our Winters, which was why this post originally piqued my interest. I figured if a fiery conversation was going to happen it would be on that topic.
digaaron":a9f0ijt1 said:
Welcome notwithstanding what argument you reignited! While admittedly I'm one of the few ski writers who looks at anthropogenic climate change with a healthy degree of skepticism, I'll enjoy reading your piece. In which outlet will it be published?
Yes, two debates actually. The most recent climate change thread here on FTO was in 2014: viewtopic.php?f=10&t=11265 And an even longer one from 2011-2013: viewtopic.php?f=10&t=9675digaaron":166znicj said:
Please tell me what the #$^%MarcC":lo1tooqh said:
has to do with averages??????Tony Crocker":lo1tooqh said:
Evren
New member
I rarely let the opportunity pass when I can contradict Marc_C or Admin but yet... on this January dry-spell argument... all signs point to yes and "it is decidedly so".
There was a TA in an intro stat class, 20 years ago. He started one discussion asking, "You flip a coin 40 times and it comes up tails. What are the probabilities on the 41st? How would you bet?" We all said 50-50 and it doesn't matter -- thinking we had avoided a simple curveball. He said, "No, what you have here has got to be a loaded coin. Bet on tails." It is good to have some of that in your thinking. Tony, you are not dealing with people here who think there is an angel on their shoulder if they timed a few traffic lights just right that one time. We know about confirmation bias and "availability heuristic" (though I had to look up the name on that one). There is also a similar one where people tend to give more weight to outlier events, because they are easier to recall.
In other news, I've decided to bite the bullet and get a full Alta Pass after 7 years. Along with an Epic. Dropping Snowbasin. When things come together just right on those outlier days, Snowbasin is heaven and I'd have it all to myself. But the frustration of early season and lean years done worn me down.
There was a TA in an intro stat class, 20 years ago. He started one discussion asking, "You flip a coin 40 times and it comes up tails. What are the probabilities on the 41st? How would you bet?" We all said 50-50 and it doesn't matter -- thinking we had avoided a simple curveball. He said, "No, what you have here has got to be a loaded coin. Bet on tails." It is good to have some of that in your thinking. Tony, you are not dealing with people here who think there is an angel on their shoulder if they timed a few traffic lights just right that one time. We know about confirmation bias and "availability heuristic" (though I had to look up the name on that one). There is also a similar one where people tend to give more weight to outlier events, because they are easier to recall.
In other news, I've decided to bite the bullet and get a full Alta Pass after 7 years. Along with an Epic. Dropping Snowbasin. When things come together just right on those outlier days, Snowbasin is heaven and I'd have it all to myself. But the frustration of early season and lean years done worn me down.
Marc_C
Active member
All I know is that when I moved here 15 years ago, all the local weatherpersons referred to "our often/usually/typically dry mid-January" and have done so each year since. Direct experience has borne that out. Tony makes three key mistakes:Evren":263eu5fn said:
1. He keeps thinking we're saying "on average it's usually dry in mid-January", what's more with statistical accuracy. What we've *actually* always said is that "we often seem to have a dry spell mid-Jan, but the month averages out for total snowfall". Our weather also usually occurs in 4-6 week cycles, with the greater bulk of winter storms starting in mid-November. Project that out and you get a often dry mid-January.
2. He says "see, Jan 11 has an average snowfall over the past 31 years of 9.6", so mid-Jan can't be any drier than the rest of the month", conveniently forgetting that if Jan 11 had three 100" snowstorm years and zero inches in the other 28 years, that day would still have an average of 9.6". This is what I mean by saying that averages smooth out the differences and why relying just on averages is a flawed analysis. A correct analysis would start with all possible storm periods in Jan (which I believe would be on the order of [N![31] - ordering duplicates] ) and then compare them to all other possible storm cycles in each of those 31 winters, then test against the null hypothesis. There's also the initial analysis to determine if it's normally distributed data.
3. Dry does not mean there must be an inversion. He tried that flawed analysis, too.
It's a daunting. I'm more than happy to go with personal experience and local weather geeks. Even when it sucks it's better than the Northeast!
This is absurd. Weather can just as easily occur in one or two week cycles. If 4-6 weeks had sufficient persistence to make mid-January abnormally dry that would show up in negative month-to-month correlations and even (horror of horrors!) in averages.MarcC":1megnvb9 said:
The above is unquestionable correct. However, a tendency toward 100 inch dumps and extended dry spells vs. more consistent snowfall would show up in higher standard deviations, increased probability of >90 and <30 inch snow months, etc. This is easily evident when you compare Sierra areas with 400 inch average snowfalls to more consistent areas like Targhee, Brighton/Solitude, Wolf Creek, Whitewater.MarcC":1megnvb9 said:
The Alta Guard data goes back to 1946. Monthly snowfall from smallest to largest instead of chronological.
Dec Jan Feb Mar
12.3 1 34 23.8
17 19.5 35 33
17 26 39 35
20 28.5 39.75 35
27 38.5 40 44
34 39 41 45
39.5 41.8 45 45
40 42 49.7 46.5
43.1 42 50 47
47.5 44 53 47.2
49 46 53.4 50.1
50 50.5 56 53
51.5 54 56.3 53
53 56 57 53.8
53 57 58 60
53 58 58 60
55 59 60.5 61
57 61 61 62
57.2 64 61.5 63
62 64.5 61.5 63.5
63 64.5 62 64.75
64.85 66.2 63 68
65 70.75 66 69
66 73 66 70
67 73 67 70
69 74.3 68 ---
70 74.5 68 70
71 75.5 69 71
71.5 78.5 72 79
73.5 81 72 80
73.8 82.8 73 82
78.7 83.5 73.5 82
79.5 84.5 73.5 84
80 85 75 84
81.8 86 77 84.5
82.5 86 77.9 85
83 88.5 79.5 85
84 94.5 82 85
86.1 96 84 87
86.4 99.5 84.1 92
91 100 85 92.3
91 100.9 85 93
96 103 85.5 93
97 103.5 86 93
101 104 88 93.8
105 104.5 91 97
106.5 105.1 91 97
107 105.3 92.5 99.5
107 107.5 97.5 100
112 108 97.5 100
114 112 98 101
119.2 112 100.5 104
122 113 102.9 109
124.5 113 103 110
128.2 113.5 104 110.9
131 115 104 113
132 122.7 105 114
132.6 128.9 107 115.5
137 132 107 123
141 133 110 124
142 134 112.5 128.9
146.5 141.5 112.7 129
151 143 119.5 135
156 143 129 142.2
159 148 130 150
160 150 131.5 151
161 165.3 132 153.6
164.8 168 134.05 163
165 186 148 164
184 187 155 165
244.5 199.7 156.6 183
91.0 91.7 82.6 88.9
45.7 41.5 29.4 36.0
Averages and standard deviations at the bottom. Looking at the extreme lowest months at the top of the table you get a message consistent with the standard deviations: December is the most volatile month, followed by January, March and February.
Uhh, no! The Utah residents were the ones using the inversions as the demonstration about dry spells and socal and I who produced the SLC inversion data showing peak "inversion season" lasting from mid-December to about the first week of February. Furthermore Jim Steenburgh has explained in great detail the reasons for the mid-winter concentration of inversions.MarcC":1megnvb9 said:
My personal experience is concentrated in mid-March and has also seen an unusual number of dry spells. Since inversions are essentially non-existent by then, it was obvious to me that "dry" was a necessary but not sufficient conditions for an inversion. This eventually led to my investigation of the more recent Alta daily data and sequence of consecutive dry days in the 31 day months:MarcC":1megnvb9 said:
This did not surprise me at all because of:
1) My personal March ski experience in Utah, which dates farther back than to when either MarcC or admin (or Evren I suspect) moved there, and
2) My overall collection of ski data, in which many of the "bad" seasons (76-77, 80-81, 86-87, 11-12) are characterized by widespread December western droughts that severely retard the time at which ski areas get adequately covered.
As for "local weather geeks," I would be astounded if Steenburgh, Trumper, Thayer, any of those guys would say dry spells are more likely in January than December.
I have mentioned before that Utah residents are more likely to recall January dry spells when they are freezing and choking on particulate smog than March dry spells when they are enjoying 60+ degree shirtsleeve weather and a choice of outdoor summer activities as well as skiing.Evren":1megnvb9 said:
Recent years are always remembered more than more distant ones. Chris Steiner of zrankings.com wrote up a nice analysis of the most recent terrible western ski season. But there was no comparison or even mention of 1976-77, somewhat understandable since that was before he was born.
What we have in this situation is the last 5 years when Alta's January snowfall has been 55% of average and thus by far the driest winter month. Even the last 15 years January has been 86% of long term average and lower than both December and March. You push that data back 40 years and the presumed effect disappears. Volatility of snowfall is such that a decade is marginally adequate for estimating season snowfall. For individual month snowfall patterns I would think 20 years would be the bare minimum to consider drawing this kind of conclusion.Evren":1megnvb9 said:
I have yet to see any comment from the Utah locals why:
I do not dispute the frequency of January dry spells. I contend they are essentially equally likely in December and March. And if you want to nitpick and choose a "most likely winter month for dry spell," the data argues slightly in favor of December.
is not a valid analysis of the relative incidence of dry spells within the 31-day winter months, despite posting it 5 times.
I do not dispute the frequency of January dry spells. I contend they are essentially equally likely in December and March. And if you want to nitpick and choose a "most likely winter month for dry spell," the data argues slightly in favor of December.
Tony Crocker":2ppt4yyo said:
Marc_C has already done that, but you refuse to do the work. Not my problem.
And you have yet to address why your admitted "personal experience (that) is concentrated in mid-March" doesn't count less than those of us who actually live through January in Utah year, after year, after year. But, then again I don't expect you to.
I have skied March in Utah in 24 different seasons. I don't claim that's statistically conclusive, but it's at least as valid as your living in Utah for the past 10 Januaries, which have had demonstrably lower than long term average monthly snowfall.admin":3ppjv98x said:
MarcC has vaguely suggested an alternative analysis while suggesting that's it too onerous for most people to undertake. He has never commented directly upon the sequence of snowless days at Alta that I have posted 5 times. And neither have you.MarcC":3ppjv98x said:
Tony Crocker":p6k0728o said:
You come for a single week on a vacation every March. Otherwise you're in southern California hundreds of miles away. I've been here 365 days a year for a decade, about 8 miles from AltaBird, including 6 above average winters, one of which was humongous. I've skied up to 101 days in Utah each season. You're really trying to equate the two? Seriously "at least as valid"? Do tell! That California weed must be really, really good.
Go Mammoth!
Which does not address that it's still only a decade. The 8 Januaries of 1993 through 2000 averaged 144 inches at Alta. This was before either Marc was in Utah. If admin's decade in Utah had been the 1990's he would no doubt be advising vacationers how they had to come during January because there was so much more sick powder than any other time. Only two of the past 15 Januaries have exceeded that previous 8 year average.admin":22ou6v1z said:
Since Alta has been kind enough to post its day-by-day snowfall for the entire period admin has been living in Utah, and the pattern of daily snowfalls is what's under discussion here, yes I think I'm at least as qualified as admin to analyze that.admin":22ou6v1z said:
Mammoth averaged 430 inches during its best decade 2002-2011 and 280 inches during its worst decade 1984-1993. A decade is marginally adequate to draw clear conclusions about weather even at the seasonal level, and not even close to adequate for short time frames like a month.admin":22ou6v1z said:
And notice that admin continues to address tangential topics while ignoring the sequence of snowless days during Alta's winter months. He would do well on the presidential debate stage. If you can't answer the question you've been asked, change the subject.