Tuesday, June 12, 2007

Severe thunderstorms likely across southern MB today..

A hot and humid airmass combined with a slow moving cold front to our west will likely trigger another round of severe thunderstorms over southern MB this afternoon into this evening. A cold frontal trough this morning extends from Arborg through Portage La Prairie to west of Pilot Mound, and this feature will likely focus severe thunderstorm development later today mainly west of the Red River valley, pushing into the Red River valley this evening. Looking at the soundings this morning, the potential is there for massive thunderstorms of 60000 feet with energy values of 3000 j/kg or more! Yesterday, the same trough line produced numerous severe thunderstorms over southeastern SK with quarter to golf ball size hail, and damaging wind gusts to 100 km/h or more. These severe weather threats will likely be repeated today, except this time over southwestern MB. Discrete supercell thunderstorms may also give isolated tornadoes. Exceptionally heavy downpours will also accompany the storms thanks to a very humid airmass in place east of the frontal trough with dewpoints in the 20-22C range. These can lead to locally flooding rainfall rates of 50-100 mm/hr possible. Put it all together, and you have the ingredients for a very active afternoon and evening over southern MB today!


  1. Whew! - stifling out there. Currently 31C at my site with a 23C dewpoint giving a humidex of 41! Thunderstorms starting to erupt over northern North Dakota southwest of Killarney. Could be some explosive thunderstorm development over the next couple of hours in hot humid airmass over southern MB. Stay tuned!

  2. The front came thru Winnipeg already, dewpoints have dropped and the air is much more comfortable

    There are a few showers/tstorms off to our southwest, that appear to be weakening. With the loss of daytime heating and the lack of a low level jetstream... the best chance for severe storms seems to be along an outflow boundary just west of the city.


  3. I'm amazed that the front went through here dry.. it's like it was accelerated through by outflow winds from those western storms before anything could develop on it. Darn.. I was hoping for some active storms tonight.

  4. I recorded a 32.8 C high in southern River Heights.

    I don't know... the whole episode yesterday was completely over-hyped in my very amateur opinion. An EC media guy was on CBC at least twice and it escalated to where you should hide from a tornado. I was watching radar, satellite, and lightning and I couldn't see any of that happening. Thinking back to 2005, when we were whacked by a supercell, half the province erupted into a mushroom cloud on satellite. Yesterday seemed too disorganized to develop into anything scary. Even the places that got rain didn't seem excessive.

    Just makes me wonder if EC has a guy that loves media work too much or being caught flat-footed last summer with the tornado north of the city has made EC trigger happy.

    The most humorous episode was on Global where they made it the lead item. The reporter said the tornados were starting; a waterspout was sighted on Lake Winnipeg, but it didn't last long because it had "less friction." I must save that clip.

  5. I've recently moved to Winnipeg from Ontario. I find great comfort in knowing what the weather is going to be, so I often watch the news for the 5 day weather forecast and have a little icon on my computer from the Weather Network which gives me updates as they come. In Ontario the forecast was more or less always bang on. But incredibly, here in Winnipeg, it's rarely accurate! The five day forecast seems to be freshly pulled from a hat every day; its always different!

    Rob, do you think that it's difficult to predict Winnipeg's weather, and if so, why?

    Last night when I heard that there were Tornado and storm warnings, I finally had enough. I didn't change my plans to go downtown. I caught a movie with some friends and then sat at the Kings Head patio and sipped a beer in a breezy, lightly misted evening.

  6. Hi Michael.. and welcome to Winnipeg!

    I'm from Ontario as well, (grew up in beautiful Niagara) and came to Winnipeg about 8 years ago. Believe me, people in Ontario complain about the weather forecasts there as well. When it comes to weather forecasts, people will always remember the forecasts that didn't work out, instead of the ones that do.

    The weather in Winnipeg can be more variable and extreme than Ontario, which can make for more difficult forecasts at times. But Ontario can be tricky too with the effects of the Great Lakes and variable topography. Both climates have their challenges!

    Note also that the forecast for Winnipeg is pretty much automated from Montreal beyond tomorrow's forecast, so Day 3-4-5 forecasts can often swing wildly from one day to the next. The forecasts for today and tomorrow are produced locally in Winnipeg, and are usually much more reliable. Note also that the forecasts from the Weather Network can differ quite a bit from EC's forecasts.

    As far as yesterday was concerned, I think EC was totally justified in playing up the potential for severe weather (including tornadoes) The setup was certainly there for very powerful storms to develop. For whatever reason, the storms weren't as bad as expected.. but EC shouldn't be blamed for alerting the public about the potential for severe weather.. that's their job (and in fact, some places north and west of Winnipeg did get large hail and damaging winds last evening) Part of the problem is that sometimes the media can get a bit overexcited about these messages, and overhype the message that EC is trying to give. But that's out of EC's control.. media is always looking to play up any story.

    Bottom line.. weather forecasting is a tricky business.. trying to predict the future is never a for sure thing. But overall, the weather forecasts in Winnipeg are about as good as anywhere else in the country..

  7. I realize this is months late but THANKS for the response, and I'll take that info to heart ;)