The temperature is struggling

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I commented back in 2008 on the ridiculous vagueness of some of the brief weather forecast summaries on BBC radio ("pretty miserable by and large," and so on). I do sometimes miss the calm, scientific character of American weather forecasts, with their precise temperature range predictions and exact precipitation probabilities. In recent days, on BBC Radio 4's morning news magazine program, I have heard an official meteorologist guy from the weather center saying not just vague things like "a weather front trying to get in from the north Atlantic," or "heading for something a little bit warmer as we move toward the weekend," but (more than once) a total baffler: "The temperature is going to be struggling." What the hell is that about?

I'm suppose to visualize a point on the temperature scale struggling? Who is it struggling with? What is it struggling to do?

Don't answer that. You know I hate comments. I try to avoid ever clicking on the button on the bottom left that opens comments, but sometimes when reaching for the Publish button I clumsily… Oops. Just clicked it. Damn.



54 Comments

  1. Karen said,

    January 27, 2017 @ 8:00 am

    I expect that he means metaphorically struggling to reach some acceptable measurement.

  2. Ari Corcoran said,

    January 27, 2017 @ 8:06 am

    The Goon Show did it for the BBC with"winds light to variable" in December 1955:
    http://www.thegoonshow.net/scripts_show.asp?title=s06e14_the_greenslade_story

  3. postageincluded said,

    January 27, 2017 @ 8:30 am

    Sorry, Prof, but they're like that because of the way the weather itself works here. The national forecast in temperature ranges and probabilities wouldn't tell you much because the ranges would be high and the probabilities low.

    On the other hand, telling the nation that the temperature will be "struggling" gives a firm indication to everyone that, though it might warm up a bit during the day, it's not going to get as warm as you'd expect for this time of year – and that forecast will probably be a reasonably accurate one from the sub-tropical Scilly Isles to sub-arctic Shetland.

  4. Vicki said,

    January 27, 2017 @ 8:52 am

    @postageincluded:

    That could be said more clearly in only a few more words: "warming slightly, but temperatures will be/remain below normal."

    That avoids the animism/anthropomorphism of the idea that the weather/air temperature is *trying* to get warmer, and the implication that everyone wants it to be warm. I've lived most of my life in places where too-hot summer days were as real a possibility as too-cold winter ones, and different people had different opinions about whether a below-normal high was a good thing in spring and summer.

  5. D.O. said,

    January 27, 2017 @ 8:52 am

    I thought Prof. Pullum likes that language loves ambiguities like dogs like (ahem) fresh cut grass. And this is a pretty understandable expression. A quick internet search shows that the phrase temperature will struggle to do this or that is pretty common even on the Trump's side of the Atlantic. Then it is a one small step to the bare temperature will struggle.

    There is or at least was a Ukrainian description of weather that can be directly translated as "no weather" or "no kind of weather". Care to guess what that means?

  6. Picky said,

    January 27, 2017 @ 9:22 am

    @vicki:

    But why should we try to avoid the anthropomorphism? Isn't it common and innocent enough to treat the forces of Nature as wilful? (Capital N for Nature's name.)

    "The weather tried to kill him, it tried its level best …"

  7. phspaelti said,

    January 27, 2017 @ 9:25 am

    Northwest, as you can see, they're gonna have some very, very tall trees.

  8. DH said,

    January 27, 2017 @ 9:36 am

    @postageincluded

    I agree that forecasts that cover an area the size of Great Britain will have to be vague. What I don't understand is what the point of such a forecast would be. We do have geographic variation in weather in the U.S and for that reason eschew the kind of regionally undifferentiated forecasts you describe. Why is it helpful to strip most of the content from the forecast in order to say something likely to be true in two places whose weather has almost nothing in common?

  9. David L said,

    January 27, 2017 @ 9:45 am

    My mother had a nice expression: "It's trying to rain." It meant that condition when the air is damp and you feel little pinpricks of moisture on your face, but you couldn't say it's exactly raining in an overt way.

    American forecasts always sound very scientific, with their probabilities of precipitation. But I have never understood what it means to say there is a 70% chance of rain. Is it a statement about the aggregate outcomes of various models? A measure of the confidence (based on past performance?) placed in one particular model? Something to do with different outcomes of the same model starting from a range of initial conditions?

  10. Paul said,

    January 27, 2017 @ 9:48 am

    That reminded me, a few years ago, the BBC Radio 4 PM programme did have a go at these vague weather forecasters. Eddie Mair's team tried to get some traction behind tightening up the terminology: people were complaining that they couldn't even remember what part of the country a given statement was supposed to be about, so they agreed to be more strict on prefacing each comment with the name of a specific region:
    http://www.bbc.co.uk/blogs/pm/2009/10/in_pm_tonight_brand_new_weathe_1.shtml
    This improved things for a while – way back in 2009 apparently, as far as I can tell! – but I think they've gone all vague again since… The emphasis is back on the chattiness and friendliness…

  11. Bart said,

    January 27, 2017 @ 9:56 am

    Isn't that (IMO) ugly use of 'struggling' a Britishism?
    I've heard it used anthropomorphically before, eg in a BBC documentary 'The windows of the Bodleian Library struggle to let in enough light'

  12. postageincluded said,

    January 27, 2017 @ 9:59 am

    @Vicki
    They do often say something like that instead of "struggling". I expect they use the longer form when they have less to say.

    I don't have your antipathy to "struggling" though. That doesn't mean that I, or most people in the UK, believe in spirits governing the weather. Because "struggling" isn't really "animism" or "anthropomorphism"; it's just a metaphor, and one that's widely understood and used in the language generally. As a born and raised atheist I really can't get exercised about it.

  13. postageincluded said,

    January 27, 2017 @ 10:15 am

    @DH
    Short – often very short – summaries of the weather are common and regular on the radio in the UK in a way that perhaps they're not in the US. The BBC is a national radio service, so those few lines of forecast can't go into great detail. But even the regional broadcasters stay vague because the weather is just harder to predict here:

    https://www.theguardian.com/uk/2011/sep/03/uk-weather-defies-prediction-forecasters

    And of course, making halfway precise predictions that turn out to be wrong prompts a deluge of complaints.

    Why there's such an appetite for weather forecasts is a different question. Prof Pullum seems to listen to them to find out what the weather is going to be like. I'm not sure that's why most people listen to them in the UK…

  14. MattF said,

    January 27, 2017 @ 10:16 am

    @David L

    I met a meteorologist at a party several years ago and was about to ask him what 'precipitation probability' actually means, but before I got to ask, he said he was so grateful to meet a scientist (I'm a physicist) because it meant he didn't have to explain about probability. I didn't have the heart to ask my question, so it remains a mystery.

  15. Amy Stoller said,

    January 27, 2017 @ 10:39 am

    "American forecasts always sound very scientific, with their probabilities of precipitation. But I have never understood what it means to say there is a 70% chance of rain."

    Statements such as these have always annoyed me. I'm sure I'm wrong on a scientifc basis, but from where I stand, either it's going to rain or it isn't. The chances are therefore always 50–50.

    I can understand why Prof. Pullum prefers American-style forecasts to English-style ones, but here in the US the forecasts are so often wrong that I sometimes wonder why anyone bothers to make them. I prefer magic thinking: If I take an umbrella with me, it won't rain.

  16. bks said,

    January 27, 2017 @ 10:50 am

    D.O.: No weather probably means the Ukranian is in Los Angeles.

  17. raempftl said,

    January 27, 2017 @ 11:00 am

    @ Amy Stoller

    "The chances are therefore always 50–50."

    Really? You are assuming that the chances for rain are the same when the there is no cloud in the sky and when it is covered with dark clouds?

  18. Idran said,

    January 27, 2017 @ 11:10 am

    @Amy Stoller:

    Statements about die probabilities have always annoyed me. I'm sure I'm wrong on a scientific basis, but from where I stand, either I'm going to roll a 6 or I'm not. The chances are therefore always 50-50.

    :P

    (Just because there are two options doesn't mean that the two options have an equal chance of happening. "70% chance of rain" essentially means that in 70% of the simulations run based on slight changes of initial conditions, there was rain.)

  19. Guy said,

    January 27, 2017 @ 11:23 am

    @Amy Stoller

    If you roll a six-sided die, you're either going to get a six or you won't, so the chances are always 50/50. Also, when you roll a six-sided die, you will either also spontaneously turn into a penguin through random quantum fluctuation or you won't. Once again, 50/50. So don't roll any dice unless you really like penguins.

    @David L

    Aren't your first and third possibilities just special cases of the second?

  20. Brett said,

    January 27, 2017 @ 11:25 am

    @David L: Predicting the weather really accurately is extremely impractical, both because it would require too many measurements of existing conditions, and it would take too much computing power. So no model is going to be correct about something like whether it rains all the time. For this reason, the models are programmed to run multiple simulations with similar but not identical initial conditions, to see how robust the predictions are. Using these results (as well as other, less direct, error estimates), they formulate things like expected temperature ranges and chance of rain. The interpretation of the chance of rain is that, if you look at all the days for which the chance was 70%, it will rain on (approximately) 70% of them.

    @Amy Stoller: What you are describing is the fallacy known as the Principle of Indifference. Is there only a 50% chance of the sun rising tomorrow? After all, either it will or it won't.

  21. leoboiko said,

    January 27, 2017 @ 12:26 pm

    Reminds me of this anonymous winner of the 2003 Bulwer-Lytto contest:

    It was a dark and stormy night; the rain fell in torrents — except at occasional intervals, when it was checked by a violent gust of wind which swept up the streets (for it is in London that our scene lies), rattling along the housetops, and fiercely agitating the scanty flame of the lamps that struggled against the darkness. Steeling himself for battle, Fyandor, the oldest and bravest of the lamps, proclaimed, "Nay, foul wind, this will not be the night of our extinguishment!"

  22. David L said,

    January 27, 2017 @ 12:27 pm

    @Brett: Thanks. I had assumed that that was the general idea but it still leaves unanswered questions about which models they use, how they assign probabilities to different initial conditions (a model maps inputs onto outputs, so you can't construct a probability distribution of the outputs without some assumption about the likelihood of the inputs), etc.

    My larger point, though, is that when weather forecasters talk about 70% probability of rain, the average listener can't possibly be expected to have any real grasp of what that number entails, so in the end you might just as well say rain is likely, or unlikely, or probable, or highly unlikely… It wouldn't sound so authoritative but in practical terms it would be just as informative.

  23. DWalker07 said,

    January 27, 2017 @ 12:50 pm

    Not sure if it's true, but I have heard that "a 70% chance of rain" means that there is a high probability that approximately 70% of the listening area (or the area that was designated by the forecaster) will receive rain. That leaves a lot of room for uncertainty.

    In my location, I can drive in and out of rain twice on my five-mile drive to work. Also, you can see that it's raining on the other side of town even when it's not raining at my house.

    As for anthropomorphism, it's almost as bad in weather as it is in the stock market. "The broader stock market is struggling to gain a foothold"; one market forecaster said something about currencies dashing themselves on the shoals of something or other.

  24. J.W. Brewer said,

    January 27, 2017 @ 12:52 pm

    If I heard something like "the temperature is going to be struggling to get above freezing" in a US weather forecast it might be a bit unusual, but not mysterious or incoherent or so markedly odd as to take me aback. But just "going to be struggling," with the supposed unspoken implication "to get to the level one might otherwise expect given the time of year etc" would strike me as very weird. Similarly, when I hear a forecast that it will be "unseasonably warm" or "unseasonably cool" I expect that to be followed by some indication of actual predicted temperature (exact or approximate) in degrees Fahrenheit. In other words, US weather-forecast listeners are not conventionally expected to do the work of both figuring out or recalling what range of temperatures would be normal for the time of year in their part of the country and then guessing how far outside that range in the relevant direction "unseasonably" (rather than some more extreme-sounding adverb) is supposed to suggest.

  25. DWalker07 said,

    January 27, 2017 @ 1:05 pm

    Ah, here is the link: http://www.marketanthropology.com/2015/03/the-dollars-perfect-storm.html

    "Far and away the biggest thorn in a reflationist outlook has been the stalwart strength of the U.S. dollar since last July. Nautically speaking, it's been an everlasting red sunrise on the decks of those participants looking to navigate the narrows of the lost reflationary straits. Swiftly dumping the wind out of the sails of commodities and inflation expectations as they tacked higher in the first half of 2014, the thesis trade once again rolled over in heavy waters as rogue waves from the dollar surprised out of the southwest and made a strong move towards shore."

    More at the link. Quite entertaining.

  26. Leela said,

    January 27, 2017 @ 1:28 pm

    What gets me is the vagueness of 'in the Northern half of the country'. Where does the North begin and the South end?
    What's going to happen in Sheffield if 'temperatures will struggle in the North while they'll be milder in the South?'

  27. Gregory Kusnick said,

    January 27, 2017 @ 1:45 pm

    DWalker07: That nautical metaphor may be overblown, but I wouldn't call it anthropomorphism. Unlike the weather, the stock market actually does consist of people with goals they struggle to achieve.

  28. Richard Hershberger said,

    January 27, 2017 @ 2:10 pm

    Not really on topic, but I have largely given up on traditional media weather forecasts. There are websites devoted to forecasting the weather in narrow regions.

    One in my area is run by a professional meteorologist. He makes his money from clients who need very specific forecasts for very specific locations. His website gives more general forecasts for the region. This presumably is intended as marketing for his more detailed service. So turning to it, I can get a forecast that discusses where the line between ice and rain will be: vastly more useful than a vague statement that there is going to be both over the larger area. He also discusses models forecasting events several days away. This is both interesting in its own right, and more helpful. Where a standard forecast might tell me there is a 50% chance of snow in four days, he will write about how the storm system might go one way, dumping two feet of snow on me, but how another model shows it missing me entirely, with his best guess as to which is right, and when we will have a better idea.

    Another site is essentially an extended high school science class project, clearly with a specific teacher behind it. How useful it is varies from year to year, presumably depending on the composition of that year's class. At its best it is surprisingly informative. Even when less so, I enjoy their enthusiasm for potential snow.

    I get far more information and more detailed information than from even the best forecasts from mainstream media, and those mainstream media are always hovering on the abyss of some manager mandating less information and more entertainment.

  29. D.O. said,

    January 27, 2017 @ 3:27 pm

    David L : My larger point, though, is that when weather forecasters talk about 70% probability of rain, the average listener can't possibly be expected to have any real grasp of what that number entails[…]

    Average listener will be well-advised to learn up a little bit.

  30. Francisco Almeida said,

    January 27, 2017 @ 4:55 pm

    Although weather is a perennial subject of small talk, most of us are astonishingly ignorant of its basics. Contrary to common assumptions, weather follows entirely predictable patterns which the outdoorsy people of times past understood quite well. Now we look at our screens instead of at the sky and complain that the (mesoscale) weather models fail to predict what happens at the finer scale of our specific location.
    Today's computerised weather forecasting is very good but there are inherent limits. If there is a prediction for, let us say, post-frontal showers, it will be hit and miss for any given spot even if it is 100% accurate for the area as a whole.
    If one has a grasp of how the weather operates, one can supplement the extremely rich simulation outputs now freely available on the net with direct observation of what the local airmass looks like.
    Otherwise, I guess a bit of anthropomorphising is at least entertaining if nothing else.

  31. peterv said,

    January 27, 2017 @ 6:07 pm

    David L @ 09.45am:

    It is not surprising that you struggle to understand the meaning of probability statements. We've had a syntax for these statements since the 1660s, and an axiomatization for the manipulation of this syntax since the 1920s. But we still lack an agreed semantics for probability statements.

    Despite its near-universal acceptance by statisticians, we also lack agreement that probability is the best way to model uncertainty.

  32. Roger Lustig said,

    January 27, 2017 @ 7:58 pm

    The key difference between US and GB radio weather forecasts: US forecasts *can* make sense. Given the minute or less usually available, a national forecast of any utility is very difficult to deliver, even in the not-so-vast British Isles.

    But a local forecast can indeed make sense, and American radio is local for the most part. Even the "clear channel" AM stations have most of their listeners within 30 or 40 miles of the tower. Thus predicted precipitation can be described as coming from one direction or another with the result that most listeners will have an idea of when and whether they're likely to get wet.

    Want national weather? Here in the States we have the Weather Channel, which devotes much of each hour to forecasts for regions of varying sizes.

  33. James Wimberley said,

    January 27, 2017 @ 9:42 pm

    Some people listen to the shipping weather report instead, for its calm and stylised way of covering unspeakable conditions in Rockall, the German Bight, and the rest of a curious set of oceanic areas surrounding the sceptred isle.

  34. Rob said,

    January 28, 2017 @ 4:01 am

    "Where does the North begin and the South end?"
    Surely it is well-known that the North begins at Watford?

    If anyone thinks BBC Radio weather forecasts are annoying, just try their TV forecasts. The camera swirls around the country and darts around in time, leaving me thoroughly confused. Still, there is always the language to entertain: my favourite is "quiet" weather.

  35. Stephen Goranson said,

    January 28, 2017 @ 8:03 am

    Since Jan. 20 the long-term temperature rise is struggling to be reported from US government agencies.

  36. mg said,

    January 28, 2017 @ 1:43 pm

    Speaking as a statistician:

    How to interpret the probability of rain? If they say "70% probability", then you should bring your umbrella. If they say "20% probability" then there may be rain, but it's not as likely.

    The idea is that if you look at 100 days where the forecast was "70% probability of rain", you would expect it to have rained on approximately 70 of them (give or take a few).

    Weather forecasting is very difficult, especially in certain circumstances. There are some places where it's relatively easy (like deserts). There are other places that are sited at the intersection of several common weather paths (like New England), making it much more difficult to predict which weather system will prevail. And despite sophisticated computer models, there are times that no accurate long-term forecast is possible – for example, the path of a hurricane is often impossible to accurately predict even 2-3 days beforehand.

    Meteorologists are left in the difficult position of trying to give useful information in situations where there's no way to be 100% sure. Sometimes they can say "We're going to get tons of rain tomorrow", while other times all they can say is "there's a good chance of rain, but we might stay dry". Giving probabilities is an attempt to convey the level of uncertainty of the prediction.

    And I agree that it makes no sense at all to try to give one forecast for all of England. Given the variations in terrain and wind patterns, among other things, why would anyone expect the weather in Yorkshire to be the same as that in Cornwall?

  37. Andrew Usher said,

    January 28, 2017 @ 2:31 pm

    I have always heard it that a percent chance of rain should be the chance (predicted by a model) of rain falling at any one given spot, like your house. That seems the most useful definition, because the spotty nature of many precipitation events makes it impossible to give an absolute for the whole area. But I wonder if weather forecasts are consistent in this.

    k_over_hbarc at yahoo.com

  38. Lou Sigusi said,

    January 28, 2017 @ 3:39 pm

    One thing that irks me about TV forecasters here (US) is their tendency for pleonasm. They will invariably tell us that "There's a 70% chance of rain during the overnight hours". Why not just say "during the night" or just "overnight".

  39. Mark S said,

    January 28, 2017 @ 10:11 pm

    My sons (11 and nearly 13) are always concerned about "what percent of battery" their electronic devices have. As a result, I think they have a very good intuitive grasp of what percentages mean. I realize that probabilities are a step more abstract, but I think that they are at least a step up on being able to understand probabilities as percentages over earlier generations.

  40. Levantine said,

    January 29, 2017 @ 4:13 am

    Rob, Watford is just outside London. I think you mean Watford Gap: https://en.m.wikipedia.org/wiki/Watford_Gap

  41. Rob said,

    January 29, 2017 @ 6:14 am

    Levantine, you are right and I have learned something! In my weak defence I note that Wikipedia claims that Watford Gap is close to the village of Watford in Northamptonshire.

  42. Andrew (not the same one) said,

    January 29, 2017 @ 9:54 am

    While the original form of the saying certainly referred to Watford Gap, Northamptonshire, it is now often used with reference to Watford, Hertfordshire, and there is an actual point to this: it's a comment on Londoners' alleged incomprehension of anything beyond the capital.

  43. Jon said,

    January 29, 2017 @ 3:54 pm

    @mg: "Weather forecasting is very difficult, especially in certain circumstances."
    Absolutely. So the uncertainty on the estimated probability varies with the circumstances. I used to produce probability maps (unrelated to weather) in which there was spatial variation in the uncertainty. I experimented with ways of showing uncertainty, but decided in the end that the public would never grasp the concept of the uncertainty on an estimated probability.
    Weather forecasters are in a similar bind. I have wondered whether they could get the idea across by quoting a duration for the estimate, such as "At the moment, forecasts are reasonably accurate up to 16 hours ahead".

  44. Levantine said,

    January 29, 2017 @ 7:09 pm

    Rob, to be fair to you (and backing up Andrew's comment), I too used to think that the expression was "north of Watford [in Hertfordshire]" and that it was a comical way of referring to the cluelessness of Londoners like myself. It was only when I heard the full version, "north of Watford Gap", that I did my research and found out that the saying has some substance to it.

  45. Jenny Chu said,

    January 30, 2017 @ 2:10 am

    Here in Hong Kong, the most memorable bit of the weather forecast is done with neither words nor images: on the main terrestrial TV channel, an animated character called "Freddy" is asked by the meteorologist, "Well, Freddy, how's the weather looking tomorrow?" Freddy then walks to the center of the screen, and depending on the forecast, sighs dejectedly ("Ohh …"), shivers, or enthuses, "Ahh!" as the (animated) sun shines or a little cloud follows him and his umbrella off the screen.

    You can find many examples on YouTube
    https://www.youtube.com/watch?v=cggE1066xkk

  46. Keith said,

    January 30, 2017 @ 4:11 am

    @Leela said,

    What gets me is the vagueness of 'in the Northern half of the country'. Where does the North begin and the South end?
    What's going to happen in Sheffield if 'temperatures will struggle in the North while they'll be milder in the South?'

    What would happen, is that there would be a light snowfall over High Bradfield and Dungworth, sleet over Stannington, Crookes and Walkely, rain in Hillsborough, Owlerton, West Bar and the Wicker and drizzle elsewhere. In all parts, winds of around force 6 gusting to force 8. Oh, and Chesterfield Road will be closed because of flooding under the railway bridge in Heeley.

  47. Bloix said,

    January 30, 2017 @ 10:19 am

    1) As an American who works with English clients, I have noticed that "struggling" is used much more often and more metaphorically in England than in America.
    2) A link on what percentages in weather forecasting mean, courtesy of the (US) National Weather Service:
    http://www.weather.gov/ffc/pop
    and one from the (UK) Met Office:
    http://www.metoffice.gov.uk/news/in-depth/science-behind-probability-of-precipitation

  48. ajay said,

    January 30, 2017 @ 10:36 am

    On Radio 4 I've often heard "the temperature will be struggling to get above X" where X is, say, ten degrees, but never "the temperature will be struggling" tout court. I'd interpret that as "not getting much warmer, if at all".
    The BBC doesn't give national forecasts, of course, it always breaks them up by region. If you want a ludicrous broad brush, though, have a look at BBC World's weather forecasts, which give each continent about 15 seconds. ("And Africa: again, mostly hot.")

  49. BZ said,

    January 30, 2017 @ 2:58 pm

    I had no idea percentages are so hard to understand. We use them in everyday speech. People get percent grades in school (at least in the US) all the time. Nobody needs those explained. Neither is the word "chance" in the relevant meaning all that rare.

    Also, probabilities are only supplemental in forecasts from the National Weather Service. They are usually at the bottom. The main text uses works like likely, possible, isolated, etc. Most radio and TV forecasts don't use percentages at all. Also, "temperatures struggling to reach [something]" is actually quite common in the US. Then there are temperatures "flirting with" some number. The only difference between the two is that the first implies unusually cold conditions, while the second implies unusually warm.

  50. Daniel Barkalow said,

    January 30, 2017 @ 3:10 pm

    In Boston, the temperature never struggles. It often doesn't go up during the day as much as you might expect or want, but in those cases, it stays low out of a casual disregard for your plans, or, on occasion, a perverse pleasure in foiling them.

    I suspect that the temperature in Britain isn't actually any more considerate, but that weather forecasters there are too polite to acknowledge that it wasn't really trying to be nice to you.

  51. Levantine said,

    January 30, 2017 @ 5:29 pm

    I think Bloix is right about the British use of "struggling". On the BBC version of The Apprentice, Alan Sugar frequently says "I'm struggling" (with nothing else added) when trying to decide whom to eliminate. I've heard this usage from other Brits also, though it's not part of my own idiolect (I would always say "I'm struggling to X").

  52. Bean said,

    January 31, 2017 @ 10:05 am

    I saw much discussion at a recent conference that some countries' weather services (e.g., France, I think) were experimenting with providing probabilistic forecasts to the public. So, for the forecast region, they would give several forecasts, each with their own probability. The usefulness of this is that then, as the day unfolded, people would realize, oh, ok, this seems to Option 2 then, "rain beginning near noon", so we can forget entirely what Option 1 said, "sunny periods". Right now (in Canada) they only give Option 1, the most likely forecast, even though the next-most-likely one could be entirely different in its time evolution. Then people get annoyed when Option 2 is what actually happens, but the only one they saw was Option 1, and then they say the weather forecasting is bad.

    I was going to say something about POP meaning something slightly different in Canada vs. the States but I think but @Bloix covered that above. On the Environment Canada pages they colour the raindrops blue if the POP is higher than some cutoff, and grey otherwise, so I use that as my guide. Blue rain = rain gear and rubber boots for the kids, grey rain = a jacket with a hood.

  53. BZ said,

    January 31, 2017 @ 11:03 am

    @Bean,
    In most cases you will not have two drastically different options with high probabilities. Your option 1 will be "Rain beginning at noon" and option 2 will be "Rain beginning at 12:15". What probabilistic forecasts look like is:
    30% probability of more than 5mm of rain at specific place between 12:00 and 18:00
    70% probability of wind reaching gale force in at least one place in the areas on Tuesday
    10% probability of wind sufficient to cause severe structural damage in a area overnight

    (see https://www.wmo.int/pages/prog/amp/pwsp/documents/Annex-K_Probability-Forecasts-Herbert.pdf)

  54. Bean said,

    February 1, 2017 @ 9:47 am

    @BZ: I'd say that depends on where you live. In Nova Scotia, we often get drastically wrong hourly predictions, but the forecast is only updated every 4-6 hours or so, so you can be looking at the wrong prediction on the website (e.g. snow at times heavy that started 3 hours ago) while looking at a sunny day out your window with no threatening clouds. Being 3-4 hours off is very important for decisions like cancelling school, which they do frequently here. I'm estimating (and I should record this methodically next school year) 1/3 school cancellations are for storms or icy conditions that don't materialize as forecast, especially WRT timing. It makes a big difference if the snow starts at 3pm, when buses are taking kids home, or 6pm, when all the kids are mostly picked up from (onsite) after-school care. I get your point, though – I grew up in Winnipeg, where the weather was generally very well-behaved, and that was before the availability of hour-by-hour public forecasts.

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