Utah Weather

[Admin]

What elevation do you have to be above to get over the inversion layer, typically?

It varies, depending on the depth and intensity of the inversion. I live right at 5000 feet and sometimes I'm above it, other times (like right now) barely in it. I have, however, seen it reach 7000 feet.

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[Admin]

In today's avalanche report forecaster Brett Kobernik of the Utah Avalanche Center wrote:

"We have a pretty classic period of high pressure in progress right now with valley inversions, nice mild weather in the mountains and pretty stable snow for the most part.  It feels like a normal January to me."

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[Marc_C]

"We are in the thick of another inversion and dry spell, as is so typical during our Januaries."

- Kevin Eubank, KSL meteorologist.

 

[socal]

"We are in the thick of another inversion and dry spell, as is so typical during our Januaries."

- Kevin Eubank, KSL meteorologist.

Slow day at work so I'll bite. It's been a long, boring, argument over this whole January inversion thing and I think we've lost track of what the argument was about.

As posted elsewhere, following our protracted storm cycle we're now in for a long dry spell under a ridge of high pressure, which is nothing unusual for January in the Wasatch although it's coming a week or two earlier than normal.

So really aren't we, should I say, weren't we just arguing that mid-January is no more prone to inversions than early or late January?

I mean Marc_C you even said it yourself

In 11 years here, I recall many January where there were storms the first few days and during the final week, but dry for the majority of the month. The most memorable being 2003, when we had 22 straight days of inversion with zero precipitation.

Looking at the data, both the KSL and UAC seem dead on in saying January has inversions, just like, you know, the actual data shows:

 

[Marc_C]

So really aren't we, should I say, weren't we just arguing that mid-January is no more prone to inversions than early or late January?

I mean Marc_C you even said it yourself

In 11 years here, I recall many January where there were storms the first few days and during the final week, but dry for the majority of the month. The most memorable being 2003, when we had 22 straight days of inversion with zero precipitation.

There were several misinterpretations:
1. Tony and to a lesser extent you latched on to "mid-January" as being exclusively the middle two weeks. Us locals have a much looser interpretation - roughly anything between somewhere around the 5th to the 25th, or so.
2. The qualifiers roughly, generally, tends to, mostly, et al were all roundly ignored.
3. There was an attempt to attach statistical accuracy and precision to something we had always said didn't lend itself to that rigid a prediction.
4. No one has gone through the tediousness of a cluster analysis of a discontinuous time series of variable length time blocks on a year by year basis. This is something very different than daily averages across years. While there is undoubtedly correlation [to daily averages], I suspect the r value is too low to be of solid predictive value.
5.We never suggested that it's always continuously dry during that time period. There can be a little storm that clears out the bad air for a day or three and gives a 5" refresher at any point, but that doesn't have a long term impact. All it really does is serve to skew the daily averages and confuse the statisticians.

Again, all we're saying is that there is a somewhat higher likelihood of one or more dry spells, likely with an inversion, after the first few/several days of the month and that the pattern usually breaks sometime during the last week/few days of the month.

 

[socal]

I generally agreed with all the stuff you wrote, but this quote is kind of confusing, what is the is the likelihood higher than? December? That's not really true but February-November? Sure it is.

Again, all we're saying is that there is a somewhat higher likelihood of one or more dry spells, likely with an inversion, after the first few/several days of the month and that the pattern usually breaks sometime during the last week/few days of the month.

 

[Marc_C]

I generally agreed with all the stuff you wrote, but this quote is kind of confusing, what is the is the likelihood higher than? December? That's not really true but February-November? Sure it is.

Again, all we're saying is that there is a somewhat higher likelihood of one or more dry spells, likely with an inversion, after the first few/several days of the month and that the pattern usually breaks sometime during the last week/few days of the month.

I was primarily thinking outside of December, simply because December is really a crap shoot on more levels than just dry spells/inversions. Many years we don't get reliable conditions and decent bases until late in the month, yet other years all areas are at 90% or more open the second week. Frequently we do get a stormy period around xmas/end of the month, but I don't feel that is at all predictable.

 

[Tony Crocker]

There is just a monumental amount of data showing wet vs. dry weather incidence in Utah ski areas is quite even November to early April. Roughly half of days have no snow, but of course weather is streaky and short term persistent so dry spells of a week or more are possible at any time. When will we skiers remember them the most? Mostly in the early season because:

Many years we don't get reliable conditions and decent bases until late in the month [December], yet other years all areas are at 90% or more open the second week.

A dry spell like the current one is one thing: if you have a deep base there's still some interesting skiing to be had and only the most spoiled powderhounds will turn their noses up at it. If it's like December 2011 all you have are WROD's and only the most compulsive addicts will be content with that. The unpleasant valley inversions in SLC are cause for the locals to remember those more than equally frequent dry spells in March without the inversions. Due to the timing of my Iron Blosam week I'm going to remember the March dry spells more. :lol:

Frequently we do get a stormy period around xmas/end of the month, but I don't feel that is at all predictable.

No it's not. There is just no evidence whatsoever that any particular week long term is snowier than any other in LCC from mid-November to probably early April. Even in April the falloff is gradual from a rate of ~90+ inches per month at the start to maybe 40-50 at the end (average for the whole month is 70).

 

[Admin]

There is just a monumental amount of data showing wet vs. dry weather incidence in Utah ski areas is quite even November to early April.

A blatantly false statement. And don't go trucking out averages again, please.

So, you're saying that Utah Avalanche Center forecaster Brett Kobernik and KSL meteorologist Eubanks are both wrong and you're right despite their much higher levels of expertise on the subject?


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[socal]

There is just a monumental amount of data showing wet vs. dry weather incidence in Utah ski areas is quite even November to early April.

A blatantly false statement. And don't go trucking out averages again, please.

I'm confused, and seriously wondering, if looking at average snowfall isn't the way you think is fair to come up with some conclusions on how much snow typically falls in a particular period then what "data" would you use? I mean you wouldn't argue that Alta averages something like 500 inches per year would you? That's based on historical averages. Would you argue that on average Alta gets 80 inches per month? Would you argue that January doesn't get essentially the same amount of snow as Dec, Feb, and March (and not too far off in April)?

Alta says all of those facts are true http://alta.com/pages/snowfallhistory.php.

 

[EMSC]

:dead horse: :stir: :sabre fight:

 

[Marc_C]

There is just a monumental amount of data showing wet vs. dry weather incidence in Utah ski areas is quite even November to early April.

A blatantly false statement. And don't go trucking out averages again, please.

I'm confused, and seriously wondering, if looking at average snowfall isn't the way you think is fair to come up with some conclusions on how much snow typically falls in a particular period then what "data" would you use?

Storm frequency, distribution, length, and intensity for starters. You guys keep stopping at your precious averages which, as we've said 8 different ways by now, smooths out the exact variations that we're looking for.

I mean you wouldn't argue that Alta averages something like 500 inches per year would you? That's based on historical averages. Would you argue that on average Alta gets 80 inches per month? Would you argue that January doesn't get essentially the same amount of snow as Dec, Feb, and March (and not too far off in April)?

We never, ever said Jan doesn't get about the same amount as the other months, so why are you bringing that up yet again? That's precisely the average that Tony attempted to use and started all this in multiple threads. Do you really not see that a 20" one day storm each week of December yields the same arithmetic average as a 50" storm on Jan 5-8 and a 30" storm on Jan 26-27? The mean is the same but the median is significantly different.

 

[kingslug]

I printed that flowchart and will post it at work...not that it will work or change anything but at least I can say I tried...

 

[socal]

There is just a monumental amount of data showing wet vs. dry weather incidence in Utah ski areas is quite even November to early April.

A blatantly false statement. And don't go trucking out averages again, please.

I'm confused, and seriously wondering, if looking at average snowfall isn't the way you think is fair to come up with some conclusions on how much snow typically falls in a particular period then what "data" would you use?

Storm frequency, distribution, length, and intensity for starters. You guys keep stopping at your precious averages which, as we've said 8 different ways by now, smooths out the exact variations that we're looking for.

Fine, I guess the "incidence of wet vs. dry" for the months of November to early April isn't proved by the average snow in each month.

We never, ever said Jan doesn't get about the same amount as the other months, so why are you bringing that up yet again? That's precisely the average that Tony attempted to use and started all this in multiple threads. Do you really not see that a 20" one day storm each week of December yields the same arithmetic average as a 50" storm on Jan 5-8 and a 30" storm on Jan 26-27? The mean is the same but the median is significantly different.

I was just using those as examples of data/facts that get thrown around on the board. Since all of those stats on Alta's website are averages they're not really useful since they don't give you the Storm frequency, distribution, length, and intensity.

It really needs to start snowing again!

 

[Tony Crocker]

Do you really not see that a 20" one day storm each week of December yields the same arithmetic average as a 50" storm on Jan 5-8 and a 30" storm on Jan 26-27? The mean is the same but the median is significantly different.

Yes I do, and if that were a true long term pattern, January's standard deviation would be higher than December's, which it's not for the past 45 years at Alta.
Average Std. Deviation
Nov. 77.59 43.39
Dec. 96.78 48.94
Jan. 95.15 40.43
Feb. 88.80 26.83
Mar. 93.46 34.47
Apr. 78.03 37.62
You could possibly say February and March are more consistent than the other months.

Storm frequency, distribution, length, and intensity for starters.

Please explain why these issues would not be reflected in this graph, based upon 56 years of Alta daily data.

The red line of at least .01 inch precipitation should be lower during a month more prone to dry spells. If the average for that month is similar to other winter months (Is anyone arguing with that?), the light blue line of days with at least 1 inch precip (~ 1+ foot snow) should be higher. And if dry spell means "well maybe you get a few days with 3-5 inches," the dark blue line at ~3 inches or the green line at ~6 inches should show something. I see nothing that makes January stand out from the other winter months in that graph.

 

[Admin]

Tony, I'm still waiting for your answer to this:

So, you're saying that Utah Avalanche Center forecaster Brett Kobernik and KSL meteorologist Eubanks are both wrong and you're right despite their much higher levels of expertise on the subject?

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[Evren]

What Tony writes stands on its own factually, more than anyone else here (myself included). He doesn't need to go on a fool's errand proving someone else wrong. But it would be interesting to see how he rebuts others' conclusions from the same data.

 

[EMSC]

I do find it fascinating how jagged the graph is considering it represents over 100 years of data. I would have thought the red line especially would be very well smoothed. Heck, I like how in late June there are a couple of days with near zero probability of precip that sandwich a day that has nearly 1 out of 3 chances of precip for example. It feels like that shouldn't happen with weather over that long a period of time, but the data is what it is...

I printed that flowchart and will post it at work...not that it will work or change anything but at least I can say I tried...

Thanks for the 'vote'. Most useful flowchart I've seen in recent years and very relevant to basically every web forum in history I would have to guess.

 

[Marc_C]

This is why scientists have such a difficult time with statisticians. Yes, multivariate time series analysis is tedious and difficult. If you want to refute what local meteorologists say along with our 8-12 years of empirical observational verification, then *you're* the one that's going to have to do the messy analysis and stop trying to take the easy way out.

 

[socal]

This is why scientists have such a difficult time with statisticians. Yes, multivariate time series analysis is tedious and difficult. If you want to refute what local meteorologists say along with our 8-12 years of empirical observational verification, then *you're* the one that's going to have to do the messy analysis and stop trying to take the easy way out.

Just a reminder what we are now arguing about (it's tough to keep track sometimes so I'm not even sure this is right)

There is just a monumental amount of data showing wet vs. dry weather incidence in Utah ski areas is quite even November to early April.

A blatantly false statement. And don't go trucking out averages again, please.

So, you're saying that Utah Avalanche Center forecaster Brett Kobernik and KSL meteorologist Eubanks are both wrong and you're right despite their much higher levels of expertise on the subject?

What I think is the problem is that neither Kobernik or Eubanks said

There is just a monumental amount of data showing wet vs. dry weather incidence in Utah ski areas is quite even November to early April.

Wasn't correct. One said

"We are in the thick of another inversion and dry spell, as is so typical during our Januaries."

- Kevin Eubank, KSL meteorologist.

So that doesn't mean he agrees that "There is just a monumental amount of data showing wet vs. dry weather incidence in Utah ski areas is quite even November to early April." isn't true. As you pointed out frequently Marc_C, a big storm can come and dump 50 inches in one shot; so by that logic What Eubank said doesn't refute Tony's comment.

Same goes for Kobernik's comment

"We have a pretty classic period of high pressure in progress right now with valley inversions, nice mild weather in the mountains and pretty stable snow for the most part. It feels like a normal January to me."

You could say that and also say "There is just a monumental amount of data showing wet vs. dry weather incidence in Utah ski areas is quite even November to early April. " and not contradict yourself right?