The Hope Graph

There's a thing I've been doing every Spring for a few years no, privately. This year I decided to tell you all about it because I think you might find it useful. I call it the "Hope Graph."

I moved to Minnesota from a slightly warmer climate. The winters here are long, and they are made longer by the local culture. For example, in Minnesota August is a relatively cool month. One gets the impression Fall is coming during the month of August, and the occasional tree or bush that has something wrong with it so it turns red early does not help. (Personally I think we should find and kill all such plants.) Correspondingly, Minnesotans will start to pack up their summer stuff in August as though winter was only a few days away.

Out east, where I'm from, this was a perennial question: "Will we have a white Christmas?" Weather forecasters were required to tell us, starting in early December, whether or not this would happen. People worried about it. Here in Minnesota, that is rarely a question.

Both Fall and Spring here are quick, only a few weeks long. Out east, the crocus push up first, then the daffodils, then the tulips, and it takes up to six weeks. Here in Minnesota they all come up the same day and are then instantly eaten by starving marmots.

The cultural hastening of Winter, the meteorological fact that Winter comes early and leaves late like those unwanted cousins from out of town, and the quickness of the intervening seasons all make Winter loooooooong. Painfully long.

Every now and then, during the Summer, I'll experience a sudden chill. Not because it is cold, but because it occurs to me that Summer is short, and Winter is Long so no matter what the date is, if it is Summer, the end is near and if it is Winter, the end is not. When that occurs to you in July it feels chilly.

So, here's what I do. About this time of year, some time in early or mid February, I make a graph. Using climatological data, I make a graph (I've done this with a table as well) showing what day we can expect, on average, for the daily high temperature to reach freezing. In theory, five or six days of the daily high reaching about freezing is enough to start the cascade of events that clears the roads and walkways of icy and hard-packed snow. Even when it is a bit below freezing, a patch of open pavement will collect sunlight (when it is sunny) and, combined with the chemical treatment left over from winter, the bare patch starts to grow and grow. A few days in a row of high temperatures reaching about freezing makes the Winter landscape start to look different. Hopefully different.

So I figure out when that date is and the nice thing about it is that that date is always pleasantly sooner than one might expect. At present I calculate that date to be about February 23rd. That's just around the corner! If this is a perfectly average year, between about February 23rd and, say, February 28th, the pavements should mostly clear, except in shady areas, of hard packed snow and ice.

Then I figure out when the date is that the average low temperature will be about freezing. A few days of the low temperature being at or above freezing signals one of the most important unofficial holidays of the year: Point Out Dog Doo Day! This is of course the traditional day when the snow banks start to melt enough that the dog doo deposited throughout the winter begins to emerge, and we can walk around in a light jacket on the melted-off sidewalks pointing it out to each other.

This of course is no longer what happens with leash laws and poop-scooping city regulations, but it is still a great tradition.

By my calculations, Point Out Dog Doo Day should be around April 3rd or a bit after ... if temperatures this year are perfectly average.

It is a bit depressing that the time span between Pavement Melt Off and Point Out Dog Doo Day is well over a month. But this is the Month of Hope. Hope that our year will be average. Or above average.

The following graph is the Hope Graph for the Twin Cities, Minnesota (click on the graph to embiggen):

The Hope Graph The Hope Graph

This is generated using data from here. For your local area, you can find your own data. The experience of doing so will be good for you.

Of course, this all assumes average temperatures. We are currently under the spell of the Arctic Vortex, so nothing is average right now. On the other hand, the Northern Hemisphere is experiencing one of the warmest winters ever. This might mean that if the Arctic Vortex moves off the upper Midwest, we'll experience an accelerated Spring.

Or, so, we can hope.

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Honestly, I think this is genius. Even if it's not one hundred percent accurate, it's very logical and informative. Going to school in West Virginia, especially this year, has introduced me to extremely long winters and feet of snow. I feel like it never stops snowing and the temperature never rises above 32 degrees. I am constantly wondering when it will stop and the warm weather will be here. This data is a good way of attempting to figure out when it will be here. The fact that this data has been collected for many years makes it much more accurate than just a guess. I agree that this is something that is hopeful and something that people could really use. The winter weather can effect driving because of ice, which we've been learning about in physics, and knowing when to stop planning for ice is a nice date to have.

By Samantha Hoban (not verified) on 11 Feb 2014 #permalink

Greg, everyone of us who puts a sports car away for the winter does the same thing. We need it to warm up to about 40 degrees Fahrenheit during the day. And we need a good deal of rain to wash the residual salt off the roads. We are all sick of driving our winter beaters. I'm hoping for February 23rd.

By Raucous Indignation (not verified) on 11 Feb 2014 #permalink

Well here on the other side of the continent (and a little further North of you) by the end of January nearly all of the snow from the previous 3 months had melted in town. Now we have several inches again and it will likely hang around until early to mid March. A Hope chart here would have some false starts as this is quite usual nowadays though in the past it was 5 months of snow all the time.

By Smarter Than Y… (not verified) on 11 Feb 2014 #permalink

At the risk of dashing your Hope (graph), it is important to remember that the numbers in your Graph represent the dates when the daily normal temperature rises above freezing. At the MSP airport, the normal daily low temperature rises to freezing on April 4th. However, this is quite a bit different than the normal date of the last freeze of the season – which is April 25th. Since temperatures are nearly normally distributed, a standard probability distribution table can be superimposed on the normal temperatures to extract a likely last freeze date.

If anyone is interested, I made a map of the entire U.S. showing the data that Greg charted and placed it on my FB climate page:

Frost, thanks for stopping by and ruining it for everyone!

That is a great map, thanks for the link to it.

I also go to West Virginia University where I am a junior and this is the first year where we have had a day off of school because of the snow. Now WVU does not experience winter nearly as bad as Minnesota and i expect the last of our snow and ice to be melted by February 23rd. I believe Minnesota will have a late Point Out Dog Doo Day. If West Virginia doesn't melt until the 23rd then I estimate Minnesota's Point Out Dog Doo Day will be about a week late. This chart is a great way to estimate important dates and from what I have learned about estimating from my physics class this seems like a very legit way of doing that. A hope chart around WVU would have a lot of early ends and some late starts excluding this current year due to the polar vortex.

In places where winter cold is usually strong enough to cause the ground to freeze (like northern New England, and presumably Minnesota as well), early spring brings mud season. Which is a big reason why people (excluding city slickers who move up here for the scenery) prefer to live on paved roads--in a particularly nasty year, even 4WD vehicles can get stuck on dirt roads. It also means no walks in the woods (you can do severe damage to trails). One reason for the timing of town meetings is that mid-March has historically been before the onset of mud season, while people could still travel to the meetinghouse but while farmers don't have much else to do.

Lately, our snow cover has been highly variable. Some years the snow melts off in early March (or sooner), while other years I don't see my back yard until mid-April. And while it doesn't happen every year, snow in April is common enough in these parts that most people aren't surprised when it happens.

By Eric Lund (not verified) on 12 Feb 2014 #permalink

Don't complain (if you are). Here, we're hoping for a couple of years now for a drop of rain, let alone a drop in temps...

Laughing and laughing at this blog. Thank you. Here in Colorado, there's an old saying that there are two seasons, July and winter. Otherwise known as "Road construction and winter."

Hold on a second there! It is HERE, in Minnesota, where we talk about two seasons, Winter and Road Construction!

two seasons, Winter and Road Construction

I think that's true throughout the northern US. We have that saying in New England as well.

By Eric Lund (not verified) on 12 Feb 2014 #permalink

I lived in New England then moved to Minnesota. It's really true in Minnesota.

Of course, in the Boston area, the impossibility of going anywhere any time is already there so it sort of masks the effect. Also, road work, some of it, does continue during much of the winter in New England. It totally stops here .. zero. The only construction equipment you see here is when a water main breaks.