Thursday, July 09, 2009

Thunderstorms with torrential rain hit Winnipeg

A line of intense thunderstorms moved through Winnipeg Thursday morning between 9 and 10 am bringing torrential rain and pea size hail. At my site in Charleswood, my weather station recorded 48 mm of rain in about 45 minutes.. with a peak rainfall rate of 457 mm/hr at 9:41 am.. the heaviest rainfall intensity my station has recorded since it was set up in 2001. The extreme rainfall led to many problems in the city including flooded underpasses, downed power lines and water damage to the Victoria General hospital.


  1. Rob!
    When there is a red and green circles on the radar image that you have posted what does that mean?????

  2. That's the radar's mesocyclone signature.. a radar algorithm that detects rotation or strong toward and away velocities near each other. The colour and size of the circles show the relative strength and height of the mesocyclone.

    Generally, the mesocyclone algorithm overdoes things with a convective line. It's does better with single cell storms.

  3. Apparently that north and east Winnipeg bias in rainfall has been obliterared as it appears the event occurred thruout the nrthn RRV.

    I assume the Raise the Riverwalk committee will be expanding by cats and dogs not to mention Drowned Rats
    Does anyone know their webmedia address

  4. 50.2 mm total rainfall from late overnight through this morning in east Charleswood with 48.0 mm falling in the 9 to 10 AM monsoon.

  5. Rob!

    The rain was so heavy it might have caused the collapse of part of the roof in Victoria Hospital!

    The rainfall rate is the most intense I ever saw....!

  6. Will be interesting to see rainfall totals from the forks... there was another torrential downpour (not as heavy as the later one) that came thru central Winnipeg around 4:30 am. Picked up more thant just 8 mm.

    Surface trough already through Winnipeg. Lower midlevel moisture allowing for sun and destabilization before surface front sweeps away lower level moisture. Would expect atleast some activity with shear and left exit region of upper jet... NWS Grand Forks expressed concern at the dry midlevels perhaps inhibiting convection. Cumulus field developing north and east of Winnipeg...

  7. No comments about potential this afternoon?

  8. Hope Winnipeg area and east don't get anymore heavy rain this afternoon!!

    Even at my apartment complex there is about 3 inches of water on the next door shopping malls roof!!

  9. Was there any strong winds at all Rob? I slept through the event.

  10. Arc of cumulus from Winnipeg sweeping SW thru Carman and Pilot Mound... perhaps some potential for development in the Morden area off the escarpment.

  11. There was a bit of gusty winds but no more than 50 km/h gusts!

    I had a bit of pea size hail but the rain.........I should have taken some video

  12. Daniel also take a look at the Sask/Manitoba border area....a lot of activity starting to get going in the dry slot!

  13. Rob!

    I have "one" more question for you!
    (I promise just one more)

    When we talk about thunderstorms we always see the storms the strongest for the most part in the evening with maximum daytime heating!!!

    Why is that the thunderstorms will sometimes get stronger in the morning>>>???????

    You guys always talk about CLOUD cover and heating for best instability and today it was raining a cool with lots of clouds and *BOOM*

  14. I was starting to question are thunderstorms chances this afternoon and then I look at the radar!

    Lots of storm starting to fire all over the place!

    Round 2 anyone????

  15. Cell that developed off the Pembina escarpment trying to get going.. it is heading straight for Steinbach.

    A few other cells in the interlake off lake breezes and more extensive wrap around showers over SW Manitoba which as noted.. these may rotate in later this afternoon.

  16. Looking at the radar from the last hour, it seems they are moving north-northeasterly in a way. Winnipeg should be out in the clear for now but that might change if a cell develops SW of the city.

  17. That warned cell southeast of Grand Beach showing some good rotation, with strong mesocyclone signature on it. Even looks like a hook echo on southwest flank..

  18. I'm surprised that Steinbach doesn't have a warning up right now, cause the north end is getting slammed by it.

  19. Very strong shearing of updraft with these storms visible on radar an by looking at the cumulus development outside... almost seems like too much?

    Watch out if those storms can catch up to the deeper moisture and more backed low level winds off to the east...

  20. Nobody got hammered in Steinbach. Storm sailed right by.

  21. Busy afternoon... good line of cells forming off southern shore of L Manitoba along breeze front. Some extremely sheared towering cumulus visible north of the city from downtown. I am not sure how outflow boundaries will behave in such a sheared environment... but we will have to watch cumulus field south of Portage for further development. This would put Winnipeg under the gun. Any thoughts Rob?

  22. Look to your south Rob!
    Intense storm has just fired up!

  23. Yep.. I see them.. nice cell just to my south with rumbles of thunder. Growing fast, but they're also fast moving.. should be affecting south end of Winnipeg.

  24. yeah I got slammed driving home on the south perimeter around 5pm...heavy downpours with some small hail embedded...had to slow down to a crawl for awhile (while the semi's kept passing!).

  25. Big cluster of storms racing ENE southwest of Portage. These are in line to hit the city if they hold together.. any bets lol?

  26. looks like you can see those cells off to the west already...

  27. Yeah, cirrus blow off from that cluster already arching into North Winnipeg. I can't get over how fast they the storms are moving with fast upper flow.

  28. Those left south Brandon just before 6pm and seem to be following the Assiniboine angling north north east.thru Portage. (130km) in just over an hour TWN Radar.

  29. Winds are diminishing and good mammatus coming down from anvil over Winnipeg right now. Cluster appears to be weakening on radar... however new cells seem to be extending back...

  30. Wishing it were going "northne" and "weakining" doesn't seemed to have had any effect. 5 minute rain at same rate as this am here. St vital Park

  31. Rob! Big rainbow off to the east from that storm. It is MASSIVE!

  32. Very strong gust front with storm and beautiful shelf cloud.. should have been warned earlier...

  33. Any reports from Teulon/Matlock/Winnipeg Beach. That looked like a nasty cell thru there a half hour ago

  34. Rob, I've got a picture of that rainbow: (yes, I do use twitter if anyone is wondering.)

  35. Second clusters with very potent cells embedded will brush the city to the SE ...

    I am surprised EC didn't pick up on the warnings sooner. Radar, mammatus and shelf cloud all strongly suggested a severe cell. I suppose radar attenuation played a role... and it would appear we need more severe weather spotters within the city??

  36. Went for a drive on the South Perimeter and went from Lagimodere to Pembina Hwy. At about 7:50 it was a wall of rain and wind gusts were pretty intense, rocked the car. Took a lot of people on the street off guard as it came in fast and hard.

    But in a matter of about 10 minutes it was all over. Followed it back to Lagimodere, lots of lightening strikes. Back inside now and watching things unfold on radar. Looks like small band of cell south of Wpg around LaSalle at the moment.

  37. Nothing in Steinbach.

    Just north of the city there was a sub-severe storm. Nothing major. Around Ste.Anne the storms looked quite severe, likely with severe gusts and penny to nickel sized hail.

  38. What a day....I think I need a breather!!!!


    I got the Storms today in Winnipeg but was at my parents place in Elie and they got some strong winds this evening at around 7:15

  39. Rob!!
    With all said and done how rain in the rain gauge with all these storms????

  40. My Davis weather station gauge picked up 57 mm in total yesterday, while a stand alone gauge in the backyard had an even 50 mm.

    The rain was falling so hard between 9-10 am, I wonder if my gauges picked up some overcatchment from the roof of my house. I'll have to check the city of Winnipeg rain gauge network to see what their sites picked up.

  41. Deadly day in NW Ontario last night with 2 confirmed fatalities and one missing person.

    Tornadic supercells swept through the region from 7-9:30pm (our time).

    Details indicate that two cabins were wiped clear off of their foundations with the debris being thrown into the lake. 2 bodies were recovered from the water, and one is still missing.

    A dive team have been called in to drag the lake and search for the missing person.

    5 other people were in a separate cabin and they were tossed 25 feet away from the cabin as it was destroyed and they were found near the shore.

    The 2 people killed were from Ponca City, Oklahoma...and the missing man is from the same area in Oklahoma too! (IRONY)

    Click my name for the video link from one of the supercells that tracked through the area yesterday afternoon around Ear Falls, Ontario

  42. This comment has been removed by the author.

  43. That is very unfortunate. I was worried about this when those supercells moved into an environment with a more backed low level flow. This should drive home the point again to our politians... we need better radars, software, more weather offices etc. Btw, does anyone know if you can still access OSPC forecast discussion? It used to be on the old CIS server with the focn45.

    Locally, the southern and eastern parts of the city were affected by at least 4 major downpours:

    1) around 4.30 am
    2) widespread event around 9.30 am
    3) around 5.00 pm
    4) around 8.00 pm

    Would not surprise me if some areas picked at least 75 mm. Totals from YWG and the forks look dubious to me with only 30 - 35 mm. In particular the forks which was affected by the heavy downpour at 8 PM. I think there may have been significant undercatch with the evening system due to the strong winds associated with it. In any case, once again southeastern regions will likely have the highest totals. Do the city gauges back that up Rob?

  44. More info in Kenora Miner (Link on my name) from EC re Ear Falls tornado
    Timing and direction would backup Daniels comments today as well as his previous post on the cells 633pm 702,725, 806, 827 etc yesterday

  45. Fisherman's Cove Tornado was given an official rating as a F2

  46. Thanks for the link Jim...

    I imagine someone flew out from OSPC in Toronto to survey damage etc? In such a case would PASPC liason or assist given he proximity of the office?

  47. I understand it was an EC employee from Thunder Bay who went out to survey the damage.

    Very unfortunate situation. A tornado in the middle of a forest.. you're in a one floor cabin, no basement, no storm cellar.. where do you go? You don't want to be outside for fear of falling trees.. instinct would be to take cover inside the cabin which was completely swept away. Wrong spot at the wrong time. I'm a bit surprised by the F2 rating.. judging by the video and the fact that the cabin was completely blown away I thought it would have been an F3 at least. Perhaps the cabin was of very weak construction.

    Still boggles the mind that these small scale phenomena can take out a small group of cabins amongst thousands of square km of forest. Just goes to show you how fate and Mother Nature go hand in hand sometimes..

  48. Justin

    Thanks for your link and notice.

    Can't help noticing those STstorms tend to hang out along the SK,MB,ND Border and move East or Northeast. I also understand that loc is a major lightning strike center for Canada.

    What problems does the Border create when you are "chasing"?

  49. video is here:

  50. Daniel

    Re: City of Winnipeg rainfall

    The city network showed a swath of 45-50 mm through the McGillivary Blvd corridor between 4 am and 10:30 am with generally 25-35 mm north of the Assiniboine. I haven't seen an updated map with the addition of the afternoon storms.. but I'll let you know the totals when I see them.

  51. Has anyone any thoughts on Monday night into Tuesday storm potential!

    looking at the models looks like another upper level low will be crossing the region!

  52. Re that McGillvary corridor comment.. at 945am Westbound on Chevrier Pembina to Waverly at least 4 vehicles died in front of me attempting to drive thru door level water. Eastbound 10 minutes later on McGillvary ditches on the South side were filled to Road level.

  53. There is potential for another round of storms on Tuesday as noted.. but attention first has turn to upper/ midlevel disturbance dropping down from Central Saskatchewan. Clouds and elevated band of showers associated with warm air advection and mid level frontogenesis dropping SE. This compact but potent wave will start to tap deeper moisture and better instability... particularly as LLJ ramps up ahead of it tonite. Best forcing and greatest instability will stay off to the SW. I wouldn't be surprised to see a complex form over N Dakota and drop towards the Twin Cities by morning. In our area I would not expect much more than showers. Amounts are hard to guess as they will have to overcome drier air below 850 hPa.

  54. As a post script.. I am surprized EC forecast for Winnipeg does not even mention slight chance of showers.

  55. Daniel TWN has covered the bases...."no pcpn expected from Saturday eve to

    Hourly forecast from same site has 1am cloudy w/showers and 2 am isolated showers

    Your post explains the conundrum

  56. Found under Special Weather Statements for Ontario. Seems like E.C. is really hedging their bets. It's like saying snow expected in January. These and some of the other E.C. products are casting doubt that they are properly equipped to fullfil their mandate.

    ACCN10 CWTO 120729
    Convective weather forecast for the province of Ontario
    Issued by Environment Canada Ontario region
    At 3:29 AM EDT Sunday 12 July 2009.
    This forecast is issued at 4 AM and 4.30 PM daily between May 1
    And September 30.

    Note: this is not a severe weather watch warning or special weather

    Discussion of thunderstorm potential.

    Today..Tonight and Monday..Thunderstorms are not expected over

    A severe thunderstorm is defined as having one or more of the

    - wind gusts of 90 km/h or greater.
    - hail of 2 centimetres diameter or greater.
    - rainfall rate greater than 50 millimetres in 1 hour or
    Less or 75 millimetres in 3 hours or less.
    - tornadoes


  57. Daniel..

    City rainfall map for afternoon convection July 9th shows a maximum of 8-12 mm over the south end of Winnipeg south of Bishop Grandin (St Vital, Island Lakes), with a maximum of 12.6 mm in Fort Richmond area (Pembina north of Perimeter)

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