Saturday 25 May 2013

Winnipeg's Thunderstorm Drought

     We are now witnessing another side effect of the extended winter we had in April.

     Due to our late spring, it has been a very slow start to the thunderstorm season across southern Manitoba. We are now May 25, and we have yet to receive a single thunderstorm in Winnipeg. In addition, across all of southern Manitoba, only 7 thunderstorm days have occured so far.

     In Winnipeg, the beginning of our thunderstorm season this year is already a month behind. The 1981-2010 normal date to get our first thunderstorm is April 26!

    As of today, May 25, we have already reached 5th latest start to the thunderstorm season on record. Only 3 times since 1953 have we not received our first storm until June (1958, 1992 and 1995). (Note: this was determined with data from the airport only, therefore this is not representative of southern Manitoba as a whole). We'll have to wait and see in the next few days if we can manage to break this curse and not have to wait until June. It's a depressing thought!

     Here's a graph illustrating the beginning of the thunderstorm season in Winnipeg per year since 1953. The years that I added are the top 5 latest and top 5 earliest.
    
     Just a side note: as you may have noticed, there's been a lot of ups and downs the last few years. 2010's thunderstorm season had the 5th earliest start on record, 2011's had the 4th latest, 2012's was the earliest and now this year is among the top 5 latest. Call it the thunderstorm variety of weather whiplash if u will :P

     Today also marks the 274th consecutive day without a thunderstorm. So far, this is the second longest ''thunderstorm drought''. We will need to have no storms for the next 12 days to at least tie for longest:



     I'll update all these stats in the May summary next Saturday - that is if we manage to get a storm before then!



_ _ _ _ _
An important note on where I got all these stats:
From 1953-1972 and 1978-1981 I used Environment Canada hourly data from Winnipeg Int'l... As a result, in this period the data is not as precise. This is because a storm may have occured in between hourly observations that got missed.
From 1973-1977 and 1982-present I used a METAR archive courtesy of wunderground. This ensures that no thunderstorm was missed in this period because this archive includes observations in between hourly observations. And yes, I was watchful of potentially erroneous obs and I did have to eliminate a couple that I found were erroneous.

31 comments:

  1. In case you missed my response to your question Mike :
    Monday and Tuesday look like the best risk days from my point of view. I do think there will be thunderstorms in southern Manitoba on those 2 days, however predicting if Winnipeg specifically will get hit is hard to say. I think we got a good chance at at least SOMETHING though.

    Models are consistent with an organised system south of the border to end the week. Still too early to say what it will bring here but it will have to be watched. Depending on its track it could be another major rain event in parts of southern Manitoba.

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  2. Julien,
    if we do get any thunderstorms on monday or tuesday, is there a possibility of some severe cells moving north of the border or is that out of the picture?

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    1. I'm a little skeptical we'll see severe storms here in Manitoba, but I suppose a cell or two could be severe or near-severe briefly and over an isolated area IF we get as high instability as the NAM suggests. However, I'm still not 100% sure what those 2 days will bring, going to have to wait until we get closer.

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  3. JJ did you see my summer outlook for Manitoba? Looking like we could get quite the active storm season once we get going that of course is if accuweather is right. I have strong faith in them there forecasts have been quite accurate over the past few years...

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    1. Mike,
      I read it, its very interesting. I would agree with you about Acuuweather being an accurate forecasting system. Hopefully your right about us getting a lot of thunderstorms this summer.

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    2. I read it Mike.
      Sure hope we do; after 2 bad years it's time!

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    3. We're the only province west of Nova Scotia that hasn't had a severe thunderstorm warning yet this year! What a sad start to the year...

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  4. Cloud cover is expected to be dominent today, tomorrow and Tuesday... I'm only considering the storm chance as small right now for Winnipeg because of this. At this point it looks like rain with embedded thunder... If we manage to get more sun, then expect the storm chance to rise as well.

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  5. Right now I'm seeing that Monday night and Tuesday will be Winnipeg's best shot at thunderstorms as a low pressure system is expected to move through southern Manitoba. Will wait until tomorrow to give more details as things get clearer.

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  6. A note about the stats someone posted in the comments about latest thunderstorm starts on Rob's blog this morning... it appears they only used hourly data from EC which is why it's different from my stats. I actually used, as noted at the bottom of this post, that I used archived METAR for part of my statistics which means I was able to see if there were thunderstorms in between hourly observations.
    That made it a heck of a lot of work, but for the sake of statistic accuracy it was worth it ;)

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  7. If we get a lot of cloud cover over the next few days then our thunderstorm risk is lower. NAM is saying that Tuesday will be a warm and humid day of about 25-if it is right then the thunderstorm risk will be higher. Models are having a tough time forecasting this one.

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  8. Turned out to be a pretty nice day. I managed to climb up to 23.9 C at 4:00. Much nicer then I thought it would be today.

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  9. It sure did.. any sunshine right now is just a bonus.

    Let's hope we get some sun tomorrow though, that would really help boost our storm chances. I'm thinking Winnipeg's best bet will be with the cold front in the afternoon or evening because the morning stuff looks to stay to our west.

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  10. Thunderstorm activity to push into southwestern Manitoba very soon. Could locally see as much as 30 mm over there tonight and tomorrow, including Brandon.

    Those showers just south of the border that are moving in Winnipeg's direction right now are expected to weaken. We may see a few stray showers or storms tonight but not much expected at this point.

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  11. JJ when are thunderstorms likely here in #Winnipeg tomorrow? I'm hoping in the evening hours, what are your thought's?

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    1. Yeah I'm really thinking our best shot is with that cold front. Right now it looks like it should pass sometime between mid afternoon and mid evening (we'll have to wait until tomorrow to get a more precise timeframe because right now that's the range I'm seeing).

      I do think there will be storms in southern Manitoba tomorrow... but there is a disadvantage about tomorrow:

      Cloud cover. Right now there's a good chance the morning will be cloudy... but based on some models we should get a bit of clearing by midday. If we don't get any clearing, then storm threat will be more isolated and less-widespread and we get clearing the storm threat will increase...

      That's how I see it.

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  12. Just a note, Winnipeg forecast and thundercast will be about 1-2 hours late tomorrow morning. Sorry for the inconvenience considering it's a thunderstorm day! But I have no choice tomorrow unfortunately.

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  13. Looks like we'll see a band of showers, perhaps some embedded thunder late morning or early afternoon then after that hopefully we'll see a bit of clearing. Looks likely they'll be some storms in our area late afternoon or evening. Updates to come late morning.

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  14. Here's some info on my thudercast:

    The general thunderstorm risk has been classified as 'isolated, small, moderate or high'. But up to now, I haven't explained what these risks meant because I didn't really have any criteria. Well, I've decided to add criteria to what these risks mean. I'll be using this criteria from now on when I make the thundercasts:

    Isolated risk = Less than 5% chance of hearing thunder if you are in this zone
    small risk = 5% to 33% chance of hearing thunder if you are in this zone
    moderate risk = 33% to 66% chance of hearing thunder if you are in this zone
    high risk = 66 to 100% chance of hearing thunder if you are in this zone (pretty much a guarantee)

    The isolated risk is usually used for storms that are spotty in nature, isolated rumbles that are embedded in an area of rain, or if the risk is just extremely small in general.

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    1. But also note that the risk is usually smaller in the day 3 forecast than in the day 2 and day 1 forecasts. This is just simply due to uncertainty. Predicting storms 2 days in advance is not always an easy thing.

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  15. Starting to see some storm initiation near Brandon at this time. Nothing major yet, but will have to watch. I'm worried all this rain and cloud will really downgrade the risk later today for the RRV. Even though storms may continue to form to our west, there is potential that they could weaken as they approach here because of the lack of heating.


    Thursday looks a little interesting with that major system south of the border... Many models bring the warm front either right into southeastern Manitoba or along the US border. This would bring in the more tropical-like humidity from the south closer to us.
    SPC has issued a slight risk for severe storms into southern Manitoba on Thursday. I'm still not completely convinced we will see severe storms as far north as Winnipeg though; we'll be stuck in the cloud cover all day and the best dynamics are expected to remain to our south. There could be some strong storms along the US border though. Will keep an eye out for changes in the forecast.

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  16. Rainfall amounts as of 1:30 pm:

    5.3 mm South St Vital (me)
    5.1 mm University of Winnipeg (downtown)
    4.0 mm Whyte Ridge
    2.8 mm Charleswood

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  17. Julien,
    whats the best guidance for the system later this week?

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  18. Right now though, from what I can grasp, Thursday looks wet for Winnipeg. 10-30 mm possible, depending on where the deformation boundary sets up. We may get a thunderstorm, but that will depend on how far north the system moves (right now I don't think there's a very high chance of storms for Winnipeg). Best risk for storms right now looks like to our south. Some strong to severe storms will be possible in North Dakota and Minnesota, and some of these may creep into extreme southern Manitoba, again depending on how far north things move. These storms would be warm frontal.

    System looks to essentially stall out over the Dakotas on Friday. Right now it looks like we'll see scattered showers here in Winnipeg on Friday. Most of the storm activity is expected to remain to our south. We may see another 5-15 mm on that day.

    Saturday looks like we'll begin clearing out behind some leftover showers early in the morning.

    In brief:
    Thursday: wet and windy with most of the storm activity remaining south of Winnipeg. 10-30 mm of rain in the city depending on how far north things moves
    Friday: Scattered showers with most of the storm activity remaining to our south (5-15 mm possible)
    Saturday: begin clearing out after some leftover showers overnight.

    That's how I see it right now... This is in no way a final forecast; I'll provide updates regularly.

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    1. I forgot to mention that due to the easterly/northeasterly winds, areas along the escarpment could see very high rainfall amounts again with this system. 50+ mm likely in some areas.

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  19. I don't think we'll get any storms here in Winnipeg today. All this stubborn cloud today ruined our chances with little to no heating today. Many of the storms to our west are weakening as they get closer.
    There is a still a small chance we'll get something, but I wouldn't bet on it right now.

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    1. If we don't get anything tonight, then we'll either tie or beat 2011 for 4th latest start to the thunderstorm season at Winnipeg airport (depending on if we get a storm on Thursday). 2nd and 3rd place belong to 1992 and 1995 for June 3, so we'll see... it'll be a close call.

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  20. No lightning is being reported in those downpours west of Winnipeg right now. It is entering areas where there was little to heating today.

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  21. Line of heavy rain moving towards the city now. No lightning being detected right now. Time will tell if it manages to maintain its strength or not...

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  22. Wide range of amounts for Winnipeg in the models right now. From GFS's 15 mm to NAM's 89 mm. I'd call for something in between, 30-50 mm most likely.
    Just waiting for the GFS's update this morning then I'll post my thoughts.

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