With the latest model runs in, everything looks on-target. The Winter Storm Watches are up, and we're looking at 5-8 inches of snow Tuesday in to Wednesday. The NAM, which had been advertising less snow, is trending slightly more, the GFS, which had been higher, going slightly less. Still, we're looking good. Light, fluffy, and not falling too hard, although it will cause some driving nightmares I bet (skiing, on the other hand …). Wax 'em up!
9:00 a.m. Monday: still looking good. GFS and NAM both have the 0.5" QPF (quantity of precipitation) running through the Twin Cities. At 15:1 snow rations, that's 7.5 inches. Pretty good. Pretty, pretty, pretty, pretty good.
2:30 p.m. Monday: the latest NAM has us up to 7.5 QPF, which would be close to a foot of snow. Stay tuned …
Sunday, December 6, 2009
The ghosts of winters past
(Click on any charts to view larger versions)
On Friday afternoon, my housemate asked if I could dig up the weather records for precipitation for 2006 to 2007. Surely! I did, and stumbled upon a treasure trove of data—highs, lows, precip, snow and snow depth for every day back to the 1890s. Except for 1913 and the early 2000s, the data are pretty much complete.
This got me to thinking: what is a normal snow year in the Twin Cities? A lot of memories go back to the 1970s when there was a lot of snow, but what was the skiing like before then? Were winters always snowier than now? Or should we stop complaining?
Well, several hours and a 17 megabyte Excel file later (I'd be willing to share it if anyone is interested), I can provide some sorts of answers. During the average winter:
85 days have at least 1 inch of snow on the ground.
71 days have at least 2 inches,
61 days have at least 3 inches,
53 days have at least 4 inches,
37 days have at least 6 inches,
20 days have at least 9 inches,
12 days have at least 12 inches,
3 days have at least 18 inches and
0 (well, 0.3) days have at least two feet accumulated.
Another way to break it out is by the number of days with at least three inches of snow (which generally equates to good skiing). I have all these data by year (and by all, I mean all) but it'd be too long to post. But the decades break out as follows:
(* data not complete for 1912-3 or 2000-1 to 2003-4)
Now to some pretty pictures. First, from Charles Fisk's climatology site, we have a great chart of the mean and maximum snow depth, by calendar date (click to expand):
Fantastic. Here's another: percent of days, by calendar day, with at least three inches of snow on the ground (click to expand):
A few interesting things here. First, note the similarity to the trail-report derived chart from the past seven winters. If anything, winter seems to be coming later and staying later. Also just for some data points, there's a better than 50/50 chance of skiing on any given day from about Christmas to Birkie, and it's a pretty sharp drop on either side, except for some weird blip in early March, where there's a better chance of skiing on March 10 than March 3. The best stretch is January 12 to February 4, with a better than 70% chance of three-plus inches of snow. The single best days are February 2 and 3, which have each been skiable 75% of the time (with at least three inches of snow). There's probably a reason City of Lakes picked that weekend. And if we get to ski this week, we'll be bucking history: there's only a one-in-three chance of skiing on any given day in this week of December.
We can also look at different levels of snow depth. For instance, the year with the most days with at least one inch of snow on the ground was 1964-5, with 137 days.
With at least 2 inches, the winners were 1964-5 and 1981-2, with 131 days (this was the year when the record depth of 38 inches was set after storms dropping 17 and 21 inches two days apart in mid-January)
With at least 3 inches, the winner was 1981-2, with 130 days
With at least 4 inches, the winner was 1978-9, with 124 days
With at least 6 inches, the winner was 1978-9, with 121 days
With at least 9 inches, the winner was 1978-9, with 103 days
With at least 12 inches, the winner was 1968-9, with 84 days (amazingly, there were only 4 other days with at least six inches on the ground)
With at least 18 inches, the winner was 1966-7, with 45 days
With at least 24 inches, the winner was 1966-7, with 11 days
What's striking here is that all of these extreme years occurred from 1964 to 1982. And the data go for 105 years! So there was definitely a snow peak in the mid 1960s to early 1980s.
For low years, 1930-1 had just 19 days with an inch of snow, 1958-9 had but a dozen days with two inches, 1943-4 had only one day with three inches, and 1901-2 and 1930-1 were the only two winters in which four inches of snow depth was not recorded. The data are less telling here, and recent drought winters (2000-1 and 2002-3 come to mind, as does 2004-5) for which the data are not complete may compete, but if the bare ground is getting you down, just repeat to yourself: it could be worse.
These data, too, we can view as charts. First, we have a chart of the number of days with at least so many inches of snow on the ground (click to expand).
Next, we have the same data, but in 11-year rolling averages for each depth, by number of days with at least that amount on the ground (click to expand).
What's interesting here are the peaks and valleys in snowfall, smoothed over the years, as well as the overall, long-term upwards trend (although the 2000-2004 years might pull recent data down, even as 2001-2 would pull it up). There was a peak in the late 1940s and early 1950s, and then a major drop-off before huge winters from the mid 1960s through early 1980s pushed the average number of days with at least two inches on the ground over 100, from below 60. And look at the 6 inch contour—from under 20 to nearly 80, a nearly fourfold difference! The long term variation is really quite amazing.
In any case, there's no telling what the current winter will bring. We're a bit late on setting the one-inch-or-more record (although we do have October 13 in our back pocket) but, with a snowstorm in the offing, we hopefully won't fall in to the wall of shame. We'll take a look back in the spring when we revisit the climate series and look back on the winter that was. Until then, let the trail reports fly!
(And the usual disclaimer: IANAM—I am not a meteorologist. Or climatologist. Oh, and the Excel file is up to 23 MB.)
On Friday afternoon, my housemate asked if I could dig up the weather records for precipitation for 2006 to 2007. Surely! I did, and stumbled upon a treasure trove of data—highs, lows, precip, snow and snow depth for every day back to the 1890s. Except for 1913 and the early 2000s, the data are pretty much complete.
This got me to thinking: what is a normal snow year in the Twin Cities? A lot of memories go back to the 1970s when there was a lot of snow, but what was the skiing like before then? Were winters always snowier than now? Or should we stop complaining?
Well, several hours and a 17 megabyte Excel file later (I'd be willing to share it if anyone is interested), I can provide some sorts of answers. During the average winter:
85 days have at least 1 inch of snow on the ground.
71 days have at least 2 inches,
61 days have at least 3 inches,
53 days have at least 4 inches,
37 days have at least 6 inches,
20 days have at least 9 inches,
12 days have at least 12 inches,
3 days have at least 18 inches and
0 (well, 0.3) days have at least two feet accumulated.
Another way to break it out is by the number of days with at least three inches of snow (which generally equates to good skiing). I have all these data by year (and by all, I mean all) but it'd be too long to post. But the decades break out as follows:
| Decade | 0-39 | 40-69 | 70-99 | 100+ |
| 1900s | 5 | 5 | 0 | 0 |
| 1910s* | 4 | 1 | 4 | 0 |
| 1920s | 3 | 5 | 1 | 1 |
| 1930s | 4 | 3 | 3 | 0 |
| 1940s | 4 | 4 | 1 | 1 |
| 1950s | 4 | 0 | 2 | 4 |
| 1960s | 3 | 3 | 2 | 2 |
| 1970s | 0 | 1 | 4 | 5 |
| 1980s | 2 | 3 | 2 | 3 |
| 1990s | 2 | 4 | 2 | 2 |
| 2000s* | 0 | 3 | 2 | 0 |
(* data not complete for 1912-3 or 2000-1 to 2003-4)
Now to some pretty pictures. First, from Charles Fisk's climatology site, we have a great chart of the mean and maximum snow depth, by calendar date (click to expand):
Fantastic. Here's another: percent of days, by calendar day, with at least three inches of snow on the ground (click to expand):
A few interesting things here. First, note the similarity to the trail-report derived chart from the past seven winters. If anything, winter seems to be coming later and staying later. Also just for some data points, there's a better than 50/50 chance of skiing on any given day from about Christmas to Birkie, and it's a pretty sharp drop on either side, except for some weird blip in early March, where there's a better chance of skiing on March 10 than March 3. The best stretch is January 12 to February 4, with a better than 70% chance of three-plus inches of snow. The single best days are February 2 and 3, which have each been skiable 75% of the time (with at least three inches of snow). There's probably a reason City of Lakes picked that weekend. And if we get to ski this week, we'll be bucking history: there's only a one-in-three chance of skiing on any given day in this week of December.
We can also look at different levels of snow depth. For instance, the year with the most days with at least one inch of snow on the ground was 1964-5, with 137 days.
With at least 2 inches, the winners were 1964-5 and 1981-2, with 131 days (this was the year when the record depth of 38 inches was set after storms dropping 17 and 21 inches two days apart in mid-January)
With at least 3 inches, the winner was 1981-2, with 130 days
With at least 4 inches, the winner was 1978-9, with 124 days
With at least 6 inches, the winner was 1978-9, with 121 days
With at least 9 inches, the winner was 1978-9, with 103 days
With at least 12 inches, the winner was 1968-9, with 84 days (amazingly, there were only 4 other days with at least six inches on the ground)
With at least 18 inches, the winner was 1966-7, with 45 days
With at least 24 inches, the winner was 1966-7, with 11 days
What's striking here is that all of these extreme years occurred from 1964 to 1982. And the data go for 105 years! So there was definitely a snow peak in the mid 1960s to early 1980s.
For low years, 1930-1 had just 19 days with an inch of snow, 1958-9 had but a dozen days with two inches, 1943-4 had only one day with three inches, and 1901-2 and 1930-1 were the only two winters in which four inches of snow depth was not recorded. The data are less telling here, and recent drought winters (2000-1 and 2002-3 come to mind, as does 2004-5) for which the data are not complete may compete, but if the bare ground is getting you down, just repeat to yourself: it could be worse.
These data, too, we can view as charts. First, we have a chart of the number of days with at least so many inches of snow on the ground (click to expand).
Next, we have the same data, but in 11-year rolling averages for each depth, by number of days with at least that amount on the ground (click to expand).
What's interesting here are the peaks and valleys in snowfall, smoothed over the years, as well as the overall, long-term upwards trend (although the 2000-2004 years might pull recent data down, even as 2001-2 would pull it up). There was a peak in the late 1940s and early 1950s, and then a major drop-off before huge winters from the mid 1960s through early 1980s pushed the average number of days with at least two inches on the ground over 100, from below 60. And look at the 6 inch contour—from under 20 to nearly 80, a nearly fourfold difference! The long term variation is really quite amazing.
In any case, there's no telling what the current winter will bring. We're a bit late on setting the one-inch-or-more record (although we do have October 13 in our back pocket) but, with a snowstorm in the offing, we hopefully won't fall in to the wall of shame. We'll take a look back in the spring when we revisit the climate series and look back on the winter that was. Until then, let the trail reports fly!
(And the usual disclaimer: IANAM—I am not a meteorologist. Or climatologist. Oh, and the Excel file is up to 23 MB.)
Saturday, December 5, 2009
Storm speculation
For a while, the models have been hinting at a storm for the middle of next work. A big one. Three feet of snow in the mountains of Colorado, with the low then ejecting east across the Plains. At first, the models suggested that the snow would generally stay south of the Twin Cities, but recent model runs, while not changing the track significantly, have suggested that an inverted trough on the back side of the storm will sit in the Upper Midwest, setting down several inches of snow.
The National Weather Service is excited. With cold temperatures, they are preliminarily talking about seven or eight inches of snow. But they are excited because looking at analog patterns—similar situations in the past—show a storm from January of 1982, which dumped about a foot and a half of snow on the Twin Cities (one of two such storms in a three day period, leading to the greatest snow depth—38 inches—ever recorded, quite literally off the charts). But, even a foot and a half would be exciting enough!
(Again, no guarantees here; the NAM model is not biting to the same degree. We'll see.)
The National Weather Service is excited. With cold temperatures, they are preliminarily talking about seven or eight inches of snow. But they are excited because looking at analog patterns—similar situations in the past—show a storm from January of 1982, which dumped about a foot and a half of snow on the Twin Cities (one of two such storms in a three day period, leading to the greatest snow depth—38 inches—ever recorded, quite literally off the charts). But, even a foot and a half would be exciting enough!
(Again, no guarantees here; the NAM model is not biting to the same degree. We'll see.)
Thursday, December 3, 2009
Going to Ironwood
Skiing, skiing and pasties. Saturday. Be there. Or be on manmade snow at Wirth. All is well in skiland, but all will be better if a storm shapes up for next week. Something is brewing on the latest GFS, as a storm is trending further and further west, but we'll watch for some continuity, first. Often, storms will trend west and then go back towards the mean. But not always. This one has potential.
Sunday, November 22, 2009
More weather hype: snow for Thanksgiving?
There's a chance I might get to pull a Larry David—to be happy and cheery at others' expense. Why? Because on the upcoming biggest travel day of the year, Wednesday, we might get just enough snow to a) ski on and b) tie up traffic something awful.
Let me stress: might.
The models, this time of year, are less than stellar. Wednesday is still three days away. However, for several consecutive runs, the GFS model has bullseyed an area of QPF (precipitation) over the Twin Cities, with most of it looking to fall as snow on the back side of a progression of lows. Before you get too excited, consider the aforementioned inaccuracy of the models, the other models not quite showing the same thing (the NAM has most snow further east), the fact that this is a small area of precipitation so a small shift of a few dozen miles could make or break the deal, and the fact that the temperature will be near freezing, so a few degrees could make for a cold rain.
Now that I've sufficiently dampened enthusiasm, let's go to the video tape (as it were). Last night's 00Z (midnight CST for the GFS) model run showed the precipitation east of here. Since then, the following are the approximate QPF estimates for once the air column cools enough for snow. Here are 06Z, 12Z and 18Z runs. The contours are 0.01", 0.1", 0.25", 0.5" and upwards; 0.5" being dark blue.
So … that's three straight model runs with us getting at least three inches of snow, or so. This is all spun out the back of a second system and will hit warm, wet ground, so there's no telling how much will actually fall. But, it's certainly more than nothing. The next few runs should be very interesting, indeed, as well as whether other models jump on board. There will be much more to know to know tomorrow, and remember, IANAM (I am not a meteorologist).
A bit of good news if it does snow (or even if it doesn't): the models are showing a more muted warmup next weekend before the real cold comes in, so if we get a few inches of snow, with the current low sun angle, it might not all melt completely. Winter is certainly late, but it should be coming soon.
Let me stress: might.
The models, this time of year, are less than stellar. Wednesday is still three days away. However, for several consecutive runs, the GFS model has bullseyed an area of QPF (precipitation) over the Twin Cities, with most of it looking to fall as snow on the back side of a progression of lows. Before you get too excited, consider the aforementioned inaccuracy of the models, the other models not quite showing the same thing (the NAM has most snow further east), the fact that this is a small area of precipitation so a small shift of a few dozen miles could make or break the deal, and the fact that the temperature will be near freezing, so a few degrees could make for a cold rain.
Now that I've sufficiently dampened enthusiasm, let's go to the video tape (as it were). Last night's 00Z (midnight CST for the GFS) model run showed the precipitation east of here. Since then, the following are the approximate QPF estimates for once the air column cools enough for snow. Here are 06Z, 12Z and 18Z runs. The contours are 0.01", 0.1", 0.25", 0.5" and upwards; 0.5" being dark blue.
So … that's three straight model runs with us getting at least three inches of snow, or so. This is all spun out the back of a second system and will hit warm, wet ground, so there's no telling how much will actually fall. But, it's certainly more than nothing. The next few runs should be very interesting, indeed, as well as whether other models jump on board. There will be much more to know to know tomorrow, and remember, IANAM (I am not a meteorologist).
A bit of good news if it does snow (or even if it doesn't): the models are showing a more muted warmup next weekend before the real cold comes in, so if we get a few inches of snow, with the current low sun angle, it might not all melt completely. Winter is certainly late, but it should be coming soon.
Wednesday, November 18, 2009
Don't believe the hype
If you listened to Minnesota Public Radio this morning, you probably heard a conversation between the host and one of their meteorologists (who blog at the Updraft Blog, which is very good). They were talking about the possibility for a snowstorm on Monday, and made it sounds, well, not like a done deal, but like a definite possibility.
Don't get excited. This is not the case.
Is there a chance of a slight snowfall next week? Yes. Sure. The pattern will be changing somewhat, and there's a lot of energy hurling through the system which could wind up and dump some snow somewhere over the upper-Midwest. Is it something that has been on the model runs over a couple of days? Not so much. Last night's GFS (the 00z run, which comes out around 11 p.m. CST) showed a possibility of a minor snow event on Monday, with marginal heights, resulting in a wet snow which would probably melt on the warm ground. The 06z showed something similar. The most recent run shows, well, maybe some snow over Chicago? Who knows.
So, yes, there's a possibility. Keep your eye out. But I wouldn't scrape the storage wax off the good skis just yet.
(The good news is that the models are hinting at a proper winter pattern around the first of December.)
Don't get excited. This is not the case.
Is there a chance of a slight snowfall next week? Yes. Sure. The pattern will be changing somewhat, and there's a lot of energy hurling through the system which could wind up and dump some snow somewhere over the upper-Midwest. Is it something that has been on the model runs over a couple of days? Not so much. Last night's GFS (the 00z run, which comes out around 11 p.m. CST) showed a possibility of a minor snow event on Monday, with marginal heights, resulting in a wet snow which would probably melt on the warm ground. The 06z showed something similar. The most recent run shows, well, maybe some snow over Chicago? Who knows.
So, yes, there's a possibility. Keep your eye out. But I wouldn't scrape the storage wax off the good skis just yet.
(The good news is that the models are hinting at a proper winter pattern around the first of December.)
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