Sunday, June 03, 2012

Scattered thunderstorms this afternoon over Red River valley/Interlake areas... some possibly severe..

A cold frontal trough over western MB will push eastward today tapping a warm and fairly moist airmass ahead of it over the Red River valley and Interlake regions this afternoon. Cloudy skies this morning will give way to some sunshine as the afternoon progresses allowing temperatures to rise into the low to mid 20s. This will set the stage for a line of thunderstorms to develop along and ahead of the trough line this afternoon mainly from the Interlake areas in through the Red River valley including Winnipeg. Some storms may become severe especially through the Interlake where upper winds are stronger, with quarter size hail, strong wind gusts and heavy downpours possible. Storm motion will be to the east-northeast at 30-40 km/h. Clearing conditions are expected by evening as the front moves east of the Red River valley.

53 comments:

  1. Watch expanded southward and cells firing up to the west of the city.

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  2. With the latest radar image, it looks like that most of the rain will be in the south end of the city.

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  3. Rob, after these storms blow through, will there be a limited threat for storms around the RRV or can we expect a possible round 2?

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  4. Cell near Elie heading east towards Headingley, west end of Winnipeg. Not severe at the time, not even any ligghtning yet.. but growing nicely. Cross section shows mainly vertical storm at the moment..

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  5. Connor... No, threat will pass after this line goes through and winds shift to the west with drier air..

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  6. Another cell just to the SSE of Carman trying to fire up too.

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  7. That cell is now becoming less organized.. looks like its trying to split

    Daniel

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  8. Can't recall hearing any thunder. Looking to be a heavy downpour and possibly some gusts of wind.

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  9. Woodlands 2050z image indicates a v-notch on cell to the southwest of Winnipeg.

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  10. Yeah.. cell is weakening as it heads to the city. As you said, some brief heavy rain and gusty winds, maybe some lightning, but not much else. Lack of good shear not helping to maintain storm.. unlike further north in the Interlake.

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  11. Looking at the latest track of this cell:
    http://www.accuweather.com/en/ca/manitoba/weather-radar?p=accuweather

    I'd say anything south of Portage Avenue will get another thorough soaking. Lots of static on my AM radio and sporadic thunder heard out the window. Chris in Westwood at 16:09 local.

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  12. Just got a report of nickel hail west of Oak Bluff. Storm appears to be strengthening again. Cell is warned now..

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  13. You can see the dryline on radar now!

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  14. Hooking (and definitely rotation) showing up near La Salle! Here's the Weather Underground base velocity view: http://www.wunderground.com/radar/radblast.asp?zoommode=pan&prevzoom=zoom&num=1&frame=0&delay=15&scale=0.265&noclutter=0&ID=XWL&type=C0V&showstorms=10&lat=0&lon=0&label=you&map.x=400&map.y=240&scale=0.265&centerx=20&centery=-223&showlabels=1&rainsnow=0&lightning=1&lerror=20&num_stns_min=2&num_stns_max=9999&avg_off=9999&smooth=1

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  15. Would not be surprised to see a tornado warning with that cell.

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  16. Yeah, that rotation was quite evident on radar.. but nothing evident on the ground. Storm is weakening again, and warnings have been ended. Dropped nickel hail and 16 mm of rain in Oak Bluff, 8 mm rain at Brady landfill.

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  17. Any on ground reports of rotation west of La Salle, hook yes on radar at 5pm, but seems to have dropped off. CAPE and LI on the rise again, and sun peeking through so who knows!

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  18. Cell has flared up again near Ste Agathe with quarter size hail reported. Cell seems to be pulsing to severe limits every 30 minutes or so. Cell moving to east southeast towards St Pierre and Steinbach although it may not be as strong by then.

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  19. SEVERE THUNDERSTORM WATCH FOR:
    =NEW= BISSETT - NOPIMING PROVINCIAL PARK - PINE FALLS
    =NEW= WHITESHELL - LAC DU BONNET - PINAWA
    =NEW= SPRAGUE - NORTHWEST ANGLE PROVINCIAL FOREST
    =NEW= BERENS RIVER - LITTLE GRAND RAPIDS - BLOODVEIN - ATIKAKI
    CITY OF WINNIPEG
    STEINBACH - ST. ADOLPHE - DOMINION CITY - VITA - RICHER
    SELKIRK - GIMLI - STONEWALL - WOODLANDS - ERIKSDALE
    DUGALD - BEAUSEJOUR - GRAND BEACH
    PORTAGE LA PRAIRIE - HEADINGLEY - BRUNKILD - CARMAN
    MORDEN - WINKLER - ALTONA - EMERSON - MORRIS
    ARBORG - HECLA - FISHER RIVER - GYPSUMVILLE - ASHERN.

    SEVERE THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON OR EARLY THIS
    EVENING AS A COLD FRONT MAKES IT'S WAY THROUGH THE AREA.

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  20. Storm over Lake Winnipeg looking mighty impressive on the Gimli webcam!

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  21. Wow, the SPC already has a day 6 and day 7 outlook for our area.. Could be quite active next weekend.

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  22. Some of you weather/storm chasers may enjoy this airborne tornado chaser site:

    http://www.wx-pilot.com/


    Chris in Westwood

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  23. If anyone is interested, SpotWx GFS Graphs are showing CAPE Values in Excess of 2,939 J/Kg on 7pm Saturday. Along with Lifted indicies of -8, in winnipeg. Definitely something to watch, over the next few days. Also surprised how the SPC is mentioning a day 6 and 7 outlook, for our area. It might be another active week and weekend!

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  24. The GFS seems to be a bit fast compared to the other models. It appears the SPC is going more in line with the slower ECMWF solution.

    Even under the slower solution, storms would become possible Saturday evening into the overnight (maybe an MCS).

    Surface based threat on Sunday as the front pushes through late in the day.

    Any way you slice it, we could have some real interesting weather to follow on the weekend.

    Also, don't discount a risk of thunderstorms Thursday night into Friday as a system pushes through. Parameters aren't as good as the weekend still enough for some convection.

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  25. Yeah, lots of uncertainty and I think models are going to struggle with this one.. because of the i) breakdown of the blocking pattern, and ii) because of a splitting of energy between the northern and southern streams.

    We'll have to see how far east that lead disturbance can get on Thursday/Friday, and then late Saturday how two waves interact - one moving up into Saskatchwan and the other over the Central Plains. According to the GFS scenario, the northern system will push a cold front thru Saturday evening - with high instability as mentioned, but with most of the forcing will be NW and S of here.

    The model paints some over-running type precipitation as southern wave moves up towards the midwest on Sunday. It then tries to phase the two systems over S Manitoba.. lots of potential for error.

    Daniel

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  26. I will certainly not discount the Thursday/Friday system. It could be a "sneaky event" for parts of southern MB. Could see an MCS of some sort developing in North Dakota on Thursday evening and potentially affecting us overnight and into Friday morning.

    Daniel, I can't help but like the way things are shaping up for us. CPC June outlook seems to indicate a flatter/weak type of ridge extending up into our area here and there with a trough out west. They're expecting temperatures slightly above normal for us with above normal precip. Would point at a potentially good storm month for us.

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  27. Re Thursday/Friday..

    GFS at least is pretty aggressive in cutting through the upper ridge by late Thrusday/Friday.. given the strength and amplitude of that upper ridge, it may be overdoing things. Still, I think potential is there for some elevated convection to drift in from the west early Friday.

    The outlook for June is perfect for stormy weather/precipitation as you mention, with periods of heat and humidity. Let's hope it verifies :)

    Daniel

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  28. My weather station is currently offline due to a power bump last night which blew my computer's power supply. (evidently a raccoon tripped a power line in the south end last night) Hopefully will be back later today pending a new power supply installation..

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  29. Not confident about hitting that 30C in Winnipeg today with a northeast wind.. maybe 27-28C. Still a beauty out there! Better chance of our first 30C tomorrow..

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  30. 5,000 J/KG of SB/MLCAPE being shown by the GFS for Saturday afternoon/evening. 2,000+ J/KG of SB/MLCAPE through Saturday overnight. Can you say large hail potential?

    Also interested in seeing how Thursday night plays out. Models showing 1,000-1,500 J/KG of MLCAPE on Thursday evening along with a frontal boundary pushing through. Could be some marginally severe stuff to contend with on Thursday night.

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  31. Apparently MB Hydro thinks that just across the Assiniboine is also Charleswood though it's technically St. James. All the clocks were reset once I got home D:

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  32. Any thoughts on convective potential as early as tomorrow night? NWS GF makes mention of it with increasing warm air advection...

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  33. Models continue to struggle with complicated scenario that will unfold as upper ridge breaks down.

    30 C tomorrow may be tough to reach. 850 and 925 temps are about 3 degrees warmer, but NAM gives us some mid-level cloud along the warm front, keeping temps down around 28/29 C.


    Thursday nite looks like our first chance for some convection.. with lead wave tapping a 30-40 kt LLJ. Uncertainty regarding the placement of the nose of that feature, with NAM further south, and GFS north.

    Things get even murkier for the weekend.. with models not able to resolve surface pressure pattern and placement of lows and fronts. From the latest GFS.. looks like warm sector on Saturday will move up during the early evening. Very unstable but possibly capped, and uncertainty regarding best forcing/dynamics with waves over Saskatchewan and S Dakota.

    Situation may evolve into more of a heavy rain threat by Sunday, with LLJ stalling as a southern wave moves up and merges with the northern trough..

    Daniel

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  34. Re Wednesday nite..

    I think the best chance for elevated convection overnite Wednesday will be over SW Manitoba and especially down in N Dakota, where there will be a stronger LLJ and where the main moisture axis will be located. I have a feeling that showers will weaken by the time they reach the RRV, leaving us with some debris cloud.

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  35. Daniel,

    I do like the way Thursday night is shaping up. As you mention, LLJ looks pretty good with a boundary moving through overnight. Not expecting anything major but maybe a decent lightning show.

    Saturday night could be real interesting. I would expect the cap to break by early evening. Certainly a surface based threat ahead of the frontal boundary. Not sure about an MCS after that...

    Sunday is unique. Looks like a surface low moving up directly from the south. What would thunderstorm potential be like with this one? Just elevated storms with heavy rain?

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  36. Yeah its going to be interesting to see how it plays out. For Sunday its hard to speculate much because the models are struggling with the phasing of two waves. The general idea for me is - lots of moisture/instability, combined with strong forcing and the potential for LLJ to stall out somewhere over SE Manitoba - may lead to lots of over-running type convection and heavy rain along the frontal boundary..

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  37. It's interesting seeing the storms in Montana rotating counterclockwise as appose to clockwise.

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  38. I have been keeping a close eye on the SBCAPE/MLCAPE and shear values for saturday with the approach of the frontal boundary. As it is crucial in determining if the storms will become Supercell storms, that might have tornadoes. Current indications are that SBCAPE levels will rise to 3,411 J/KG while the MLCAPE will be at 2,923 J/KG all on 7pm Saturday. Those wondering about Shear Values around this time, they look to be near 40 to 44 knots. I am not an expert at this, but what I can tell from using online weather sites is that having shear values from 40 to 49 knots and CAPE values >2500 could lead to ordinary storms or supercells. This indeed will be a very interesting Event to watch out for, any thought's on my opinion?

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  39. Mike.. yes, certainly a potentially severe day later Saturday with supercells but I wouldn't focus too much on the model based severe weather indices just yet. Models can often overestimate values for CAPE and shear depending on the situation.. overdoing surface moisture or surface temperatures by not accounting for cloud cover or undercutting surface flows. They can give you a general idea of the potential istability of an airmass, but things can be quite different depending on the eventual frontal positions, upper air features and cloud cover. A few days ahead, you have to focus more on the general overall pattern and see where the upper and low level jets are likely to set up, what type of dewpoints are likely, what your surface pattern and frontal positions will be like, etc to give a general outlook. Then you can zero in more on CAPE values and shear etc as you get closer to the day. At this point, quickly looking at current synoptic fields for the weekend, it looks like main action may be more over the Dakotas late Saturday with cells drifting nort of the border Saturday night.. but again, that's just a quick look based on current models which will likely change as this system evolves.

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  40. Weather station is back up! Darn raccoon cost me a $90 repair bill!: :)

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  41. Could this be the day that Winnipeg hit's 30C?? Almost there!

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  42. It's possible.. YWG airport up to 28.5C. GEM shows us hitting 30C by late afternoon as surface winds become more southeasterly.

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  43. Models having all sorts of problems with the Saturday system. GFS is a bit slower but still brings a surface based threat to S MB.

    The NAM keeps the main juice south of the border along with the warm front. That would point to a more elevated convection event for S MB.

    Going to be interesting to see what actually happens. I would still lean towards a surface based threat for us but that could obviously change.

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  44. 30.7 at my site in Transcona as of 4pm. First 30C reading of the year at my place!

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  45. Every personal weather station in Winnipeg has hit 30C today.. but temperatures remain at 29C at the official sites of Winnipeg airport and The Forks. Goes to show you how everyone's backyard is just a tad warmer than the official sites on a sunny day with little wind.

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  46. Rob (and others), I want to talk about our radar network.

    It's aging older and older by the day, and with sites like Foxwarren running hot (which could easily be fixed in the short-term but might spring up again in the future), doesn't anyone else think that we're overdue for an overhaul of the network?

    With technologies like dual-pol that is being implemented gradually by the NWS States-side, and higher resolution and longer range radars, it'd definitely be a good topic to discuss a bit.

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  47. Whats the potential for thunderstorms tomorrrow eve?

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  48. Rob........
    My backyard temperature in ST James is sitting at 30.4C, first time this year! Except for the 55C temperature last week when my temperature sensor was in the sun.....

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  49. Anonymous,

    Looks pretty good for storms tomorrow night. System will be tracking quite slow. Shear won't be great, either but sufficient instability and moisture should help to make up for the lack of shear a bit.

    There is also a pretty nice low level jet that gets going tomorrow evening. Storm motion is probably going to be slow which could enhance the potential for heavy localized rainfall.

    Any way you cut it, I'd be shocked if there isn't a good lightning show tomorrow night in southern Manitoba...

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  50. Max of 29.6C at the airport so far today.. we'll see if it can squeeze out another 0.5C, but time is running out!

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  51. Connor..

    EC has identified its aging radar network as a high priority, which is why there was a bunch of money (over $50 million I believe) allocated to fixing and upgrading EC radars over the next 5 -10 years, including conversion to dual pole. How quickly this really happens is another matter, but at least, some money has been allocated for radar upgrades for the near future, which is a good thing and highly needed.

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  52. Max of 29.8C at YWG airport.. so close! 30.4C at the Forks.

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