That was the winter that was—mid-season report

I'd say this is the TW3 report, but the tenses would be wrong, since we're really only about half way through. So, maybe I'll call it TITWTI (this is the winter that is), or something. In any case, it's about time to examine where we stand compared to recent winters, look at some condition reports, and prognosticate where we might wind up, as well as spill some fun weather data. And, yes, there's a darned good reason I did the season recaps after the snow had melted last March: time! So this may be rather short and periodically updated.

Now, we know that ski conditions are, uh, pretty awesome. It got a late start, but since then there has been continuous skiing, with only a couple days without at least good conditions. (Ski conditions were discussed at length last year here.)

So, where do we stand? Well, first of all, we're at, as of February 10, 65 days of skiing, of which 61 have been good or excellent. We have not had to contend with the "oh no will it melt" syndrome which has plagued some past ski seasons, and the base is now up to 15 inches, the highest in nine years, with no meltdowns in sight. The City of Lakes went off without a hitch, Mora will as well, and Birkie has two feet of base two weeks before the race. As long as we can make March 15, we'll have 100 days of skiing, and an "excellent" snow year.

What's interesting is that despite the great skiing since early December (even after a couple of minor meltdowns the trails have, for the most part, been resurrected) it has not been a particularly cold or snowy winter. December was about a degree below normal, January, despite a cold start, finished just a tenth below. Snowfall through the end of January was 26.8 inches, of which 20.9 fell in December (2.8 in October, 0 in November, just 3.1 in January). With 11.3 inches so far in February, we're up to around normal. So it's been a very normal winter.

Despite some variability and unusual storms, there have been no real extremes. We've had no brutal cold snaps (no day has stayed below 0) but also no major warm-ups. The latter is, I think, the reason that we've kept our base so well. If you look back at the past few years, every one has a pretty devastating warm-up. Last January 31 it skied to 45 degrees, a week later it was 47. January '08 hit 40 twice (December '07 had as well), 2007 was, well, let's not talk about it, and other years were similar. It got me to thinking: we haven't been above 40 for more than 70 days. What are the records days under x degrees? I delved in to the data to find out.

	Longest		Second longest		Third longest
Temperature	Days	Ending:	Days	Ending:	Days	Ending:
0	7	Jan 7 1912	6	Jan 28 1904	5	Four times
5	12	Jan 12 1912	10	Jan 27 1963	9	Jan 27 1936
10	21	Feb 7 1936	15	Jan 1912/1974	13	Feb 21 1936
15	36	Feb 21 1936	16	Jan 1912/1977	15	Jan 12 1974
20	39	Feb 22 1936	25	Feb 15 1905	24	Feb 12 1904
25	41	Feb 22 1936	32	Feb 8 1978	27	Three times
27	52	Feb 19 1979	47	Feb 9 1912	41	Feb 22 1936
29	52	Feb 19 1979	50	Feb 12 1912	47	Feb 22 1978
30	58	Feb 19 1979	52	Feb 12 1912	48	Feb 25 1939
31	66	Feb 22 1978	58	Feb 19 1979	52	Feb 13 1912
32	66	Feb 22 1978	58	Feb 19 1979	52	Feb 13 1912
33	67	Feb 23 1978	58	Feb 19 1979	53	Feb 13 1912
34	67	Feb 23 1978	60	Feb 21 1979	54	Feb 13 1912
35	71	Feb 21 1969	70	Feb 22 1936	69	Feb 15 1971
36	79	Mar 7 1940	77	Feb 22 1936	75	Mar 15 1975
37	106	Mar 6 1972	84	Feb 13 1943	81	March 9 1978
38	116	Mar 12 1979	106	Mar 4 1972	105	Mar 1904/1955
39	122	Mar 22 1904	116	Mar 12 1979	114	Mar 2 2001
40	122	Mar 22 1904	116	Mar 12 1979	114	Mar 2 2001
42	126	Mar 13 2001	125	Mar 24 2006	122	Three times
45	141	Apr 3 1979	140	Apr 12 1975	135	Mar 24 1956
50	152	Apr 11 1979	149	Three times	148	Several times

Some of these data are pretty amazing. 66 days at or below freezing in 1977-8 is probably the best known. But go a couple degrees warmer, and you get 106 days at or below 37 degrees in 1972, which is, perhaps, just as impressive: it was below 37 from November 21 to March 6! And our last big snow year—the last time Minneapolis banned parking outright on one side of the street. Right now, we have a good chance of overtaking third place for the 37 degree mark, as we are just ten days away (and two weeks out of second). But there have been some impressively long cold streaks in the past. This current streak is long, and cold, but not really historic. Yet.

Please, sir, may I have another?

In January, we received 3.1 inches of snow. And had decent skiing most of the month.

In the first two days of February, we received 3.1 inches of snow.

In the next few? Here's the latest "meteogram" generated from the NAM and GFS models (through the fantastic Bufkit Warehouse, which is run by a grad student down at Iowa State who wants to work for the NWS and better get a job).

Last night, I got very excited when the 00Z GFS printed out nearly four inches of snow tonight and tomorrow and another seven from Sunday through early next week. That's 11" of snow! So this morning I woke up, checked the site, and saw that the next model run was lower (the chart shown here) or so I though, until I looked at the scale at the left and realized that last night's line was the low blue line. (In addition the newer NAM was printing out a bit more snow.) The latest GFS had us getting more than ten inches next Sunday to Tuesday. Well, uh, holy smokes. That would be amazing.

So, for now, we'll speculate. The models are still not in full agreement for next week. But they're coming together. And, boy, would another foot of snow be nice.

The inversion

The NWS points out that yesterday's evening temperature reading at 850mb (about 5000 feet) was 58 degrees (!) which was not only one of the highest readings ever during winter months but the highest of any balloon in the country. With our inversion, abundant snow cover in the direction of the surface winds and snow to reflect the sun's energy we topped out at all of 28 yesterday. And it doesn't look like the upper air will get that warm any time soon, so the chances of a major meltdown seem to be at bay.

Como and snow melting

I hit up Como again for some intervals (double pole then V2 uphill) and all around skiing. The conditions are very good, but it could use a groom. Coverage is full. The issues are that pole plants are soft in places, that the skate lane is getting pretty well packed (although better with warmer weather) and that someone ran a truck across a couple portions of the Glacier, which really needs a regroom. Hopefully they can take the machine across it before the weather turns too warm. Tonight would seem to be a good night for it, hint, hint.

As far as the snow melt goes, I'm actually less concerned now than I was yesterday for two reasons. First, the models are happier. They've backed up the huge, tropical rain storm idea and now just have us hovering in the mid-30s for daytime highs with very little moisture for a week, and then cooling back down. It's not ideal, but it should only take a couple inches off of our base if it comes to pass. As I mentioned earlier, we've dodged a bullet by having had an inversion lock in cold temperatures at the surface; it's still +10˚C at 3000 feet but 20 at the surface, and it never got near freezing today despite some sunshine. It looks like that pattern should continue, with a bit of warm-up but nothing worse than a few hours at 34˚. With January sun, we can handle that.

Second, I went in to the archives and looked at times that 8 or more inches of snow has been on the ground in January (about 40% of the time). I could find no cases where more than 10" of snow had melted in December or January, and only a couple times when 8" had. Here are some interesting analogs to make me less scared that the snow will disappear (although when February comes around, with its stronger sun and warmer temperatures, anything is possible). I can't think of a good way to graphically show this so:

2008: 8" on Jan 3, subsequent days 30/14, 37/19, 41/32, 37/27, 34/22, 31/13, 35/29, no rain or snow, melted to 4"
2005: 7" on Jan 22 melted to 0, but that took until Feb 6 and required highs of 35, 44, 33, and then later 33/28, 25/29, 26/31, 42/27, 50/31, 51/35. That was the City of Lakes Meltdown. We have four more inches of snow and those were extraordinarily high temperatures in February. In addition, there was far less snowcover that year to our south and west.
1993: 9" on the 30th melted to 5 on February 3, but only after 39/12, 45/34, 42/24, 38/22, 38/20 with no other moisture.
1992: 8" of snow on the 1st, aided by 0.8 inches but also hit with about 1/3" of rain, stuck around despite a week with highs around 34 and lows only around 31 (yes, for the first five days of the year the high was 37 and the low was 31). The snow barely melted despite a couple more days in the upper 30s. This seems like a worser-case scenario for our current situation.
1991: 8" on the 31st melted to 0 with temperatures of 43/8, 48/15, 42/35, 46/32; we are not expecting these types of temperatures and the sun was two weeks higher in the sky.
1989: 8" melted to 0 over two-plus weeks (the 8th to the 25th) with highs of 35, 37, 33, 37 (this took it from 6 to 2; it had settled from 8 to 6 already … our snow pack is rather dense so there won't be much settling) and then meted with highs of 39, 40, 40 and 35.
1986 may be the best analog: 12" on the 9th melted to 8" by the 20th, with temperatures of 42/28, 34/27, 44/24, 40/14, 22/6, 25/14, 34/11, 38/21, 39/29, 35/27, 33/28, 34/31 with no rain or snow. This would not be a bad outcome for us.
1976 went from 9 to 7 with a day at 41 and the next at 35.
1974 is another good analog. After a cold start to the month, 8" of snow on the 14th melted to 6 wth days at 39/16, 38/12, 41/24, 33/24, 34/12.
1973 melted 8" to 4" with 38/9, 46/24, 44/24, 36/25.
1952 melted 10" on the 30th to 5" with 42/30, 38/24, 37/21.

The one issue is that moisture would be a major wild card. There are only a couple of instances of a lot of rain falling on a lot of snow in January, and, while they are both a very long time ago, neither actually killed the snow pack. In 1946 melted 10" on the 4th to 4" on the sixth with temperatures of 38/25, 36/33 and 33/25, with 0.6 inches of rain on the middle day. Back in 1902, a December storm brought 0.75" of rain (and 3" of snow) but only depleted the snow pack from 10" to 4" despite 35/17, 34/15, 36/34 (with the rain and wet snow) and 36/28.

So the gist of what I'm saying is that to melt more than 10 inches of snow would require weather so extreme that we've never seen it before. A run-of-the-mill January thaw may eat away at half our base, but to lose more than 8" of snow in January is historically unheard of. Now that the three-inches-of-rain-with-embedded-thunder storm has worked its way off the models, it looks like we'll have a week in the 30s. That we can deal with.

The latest model run has significantly cooler weather in the next week—if it verifies I'd be surprised if we hit freezing more than two days, and then two warmer storms—with some rain or perhaps a lot of wet snow—the week after. So, who knows. If I had to predict, I'd say we have 6" of snow on the ground at the end of the month, with good skiing at most Metro locations and great skiing in Elk River (they are starting with more and they keep snow so damn well).

Ski on.

I can only get to two trails at most, on a good day! Check out all the trail reports at skinnyski.com

Storm speculation update

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 …

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:

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.)

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.

On the other hand

Real meteorologists take in to account all the models, look at various other data, use thinks like the bufkit (Pretty much a software package, or "kit", from the Buffalo office of the NWS, or "buf", which I don't have.) and such to make real forecasts. The NWS is down to "less than an inch," probably because of the dry air in place early on when QPF overspreads the area. Which will at least keep things dry. What good is three inches of snow in April, anyway?