Saturday, May 19, 2012

Thunderstorms bring heavy rain, hail to Winnipeg and southeast MB..

Rainfall accumulation estimates from
Woodlands radar showing track of storms
Friday evening. Note swath of yellow and
orange returns through Winnipeg and
northeast, and another line from
  Steinbach to Lac Du Bonnet. 
It was a stormy start to the May long weekend as a line of thunderstorms developed rapidly just west of Winnipeg Friday evening, tracking over the city between 8 and 9:30 pm bringing heavy rain and hail through much of the city.  The storms fired up just southwest of Winnipeg by about 7:45 pm and within 15 minutes were bringing torrential rain to southwest parts of the city. The cells continued to track over downtown bringing heavy downpours and lots of small hail, enough to accumulate on the ground in areas like River Heights and Wolseley. The storms produced a swath of about 25-35 mm of heavy rain from the southwest part of the city through the downtown core into the northeast (see radar image left), with much less rain on the southeast and northwest perimeters of the city. At my station in Charleswood, I recorded 27 mm of rain between 8 and 9 pm with a peak rainfall rate of 133 mm/hr at 8:11 pm. Even higher amounts of 30-35 mm of rain were recorded downtown (U of W) and the northeast parts of the city (E St Paul)   The storms were part of a complex frontal system passing through southern MB Friday evening that was ushering in cooler air for the start of the May long weekend. Unsettled weather with periods of rain and cool northwest winds will start off the holiday weekend Saturday with another 10-20 mm of rain possible, before drier more pleasant weather moves in by Sunday into Monday.


  1. Large area of rain over the southern RRV heading north towards Winnipeg. Rain should spread into the city from the south by 8 am and continue through the morning into mid afternoon with about 10-20 mm expected.

  2. Some lightning being reported in the cells over southern RRV and SE MB. Tops are weakening, but there could be some lingering strikes this morning especially southeast of the city.

  3. Actually, judging by latest radar, it looks like rain may not last as long in Winnipeg. Main shot of rain between 8-10 am with about 5 mm or so, then it should move off with bulk of rain to our northwest. Hopefully we can escape with minimal ran today after last nights deluge.

  4. First wave of rain moving out of the city, but additional showers and tstorms developing over the southern RRV spreading north. So looks like rainy weather will continue into the afternoon after all.

  5. First half of the long weekend looks to be a write off, but the second half looks to be more enjoyable.

    Is there supposed to be a solar eclipse tomorrow?? Hopefully things will clear out tomorrow!

  6. Another 16 mm today on top of the 28 mm last evening... 44 mm in total since 8 pm last night.

  7. Rob,

    Nice rain for you guys up north. Would love to have that rain down here. We did get a good downpour about 9 am this Saturday and some drizzle later just about 0.30 of an inch at the NWS office but around 0.50 at the airport. Fargo only had 0.01. Some more chances mid week...esp for Southern Manitoba.

    KMVX 88D is in test phase now --- testing products....and should be back in normal operation Sunday afternoon.

  8. River Park South in St. Vital only 18 mm since last night!

  9. Hi everyone...

    KMVX 88D is now back in operation as the dual pol install went good.

  10. Looking at long range models, such as the GFS, NAM and futurecast on John Sauders Site there might be a potential for thunderstorms on Tuesday Night in the RRV. Any thought's?

  11. Interesting to see the partial solar eclipse on the Fargo webcam this evening...

  12. "and futurecast on John Sauders Site"

    Take anything he says with a grain of salt. His forecasts are pure garbage. Case in point: 17 April, he forecasts 3-5 mm, we get 16. Yesterday 19 May we hit 12.3°C; he had forecast 22°C and in fact his forecast is still up on his website.

  13. Frost warnings have started up for the season.. with frost warnings issued tonight for western Manitoba and a risk of frost elsewhere. Frost warnings are issued between Victoria Day weekend and the first day of fall (Sept 21st)

    There was extensive frost this morning across southern SK including -2C at Saskatoon and Regina, and -4C at Rosetown. Drier air mainly to the west of RRV this evening with dewpoints below freezing, although a light southerly flow and some increasing high cloud may spare western MB from a more serious freeze overnight. Patchy frost possible over RRV and SE MB by morning, especially traditionally cooler areas towards the Ontario border.

  14. Comparing sunset temperatures/dewpoints from my backyard station between this evening and last Tuesday evening (when I hit a low of -0.1C the next morning) , I see we are about 2-2.5C warmer this evening. That would translate to a backyard low of +2C by tomorrow morning .. which should be enough to save us from frost. The good soaking from yesterday should help too.

  15. 34.9C today in La Tuque, Quebec (with a RH of 15%). That is by far the warmest temperature recorded in Canada this year.

    The fire risk is now extreme north of Montreal and west of Ottawa.

  16. Looks like a pretty good convective set-up late tomorrow and tomorrow night. I'm not sold on us clearing enough with the warm front nearby and capping rather weak. We could have scattered elevated convection to deal with much of the day.

    Regardless, a good chance of at least strong thunderstorms tomorrow.

  17. With the recent KMVX dual-pol upgrade, it'll be fun to use those products in times of severe weather and not have to look at some other radar where severe wx is happening far away from here.

  18. Extreme fire danger for much of Quebec right now.

    Canadian warmspot was once again there (La Baie, Quebec at 34.6C) with very dry conditions.

    There was a big wildfire in Timmins, Ontario. Hopefully now with the rainy day, the situation is better.

  19. I was really surprised how warm it stayed overnight two nights ago. I, too, was expecting temps in the 2-5°C overnight, but the airport only got down to about 7°C and the overnight low was 8.4°C in my back yard.

    That being said...

    Late this afternoon into the evening, we'll have decent moisture available aloft at all levels. A sharp thermal ridge at 850mb (red) will be positioned near the ND/MN border and arc NW over the SW RRV into SW MB, with an associated 40-50kt LLJ. It looks like the 700mb (orange) thermal ridge will push ahead, destabilizing the mid-levels early in the evening. The left exit of a 30kt jet at 700mb looks to rest over the Manitoba RRV by early evening. This will all be supported by a strengthening 40-50kt jet at 500mb arcing across Southern Manitoba from the Pilot Mound region towards Pinawa. Deep lift will be present with the right entrance of a 60kt jet over SW MB.


    All this to say that...thunderstorms will likely fire in ND tomorrow afternoon along the surface cold front as it advances eastwards. As they progress, upper-level features will begin to align and intensify to help discrete-cell storms grow upscale into a strong, linear feature that will rapidly expand and push northwards, supported by deep lift and moisture provided by the left exit regions of lower-level jets and right entrance regions of upper-level jets. Mid-level temperature profiles will destabilize later in the the afternoon/early evening, further supporting the evolution of a nocturnal thunderstorm complex.

    All that being said, this ends up being my expected risk area for today's storms:

    You can read an even more thorough discussion over in the comments on my blog:

  20. Thanks for your discussion Brad.. New post is up regarding tonight's potential. Could be a repeat of last Friday night, although I don't think I want to see another 30 mm of rain so quickly!

    Kids soccer and baseball games will be tricky to get in this evening!