Monday, May 24, 2010

Another round of showers/thunderstorms on the way

Another low pressure system moving into the Dakotas today will spread more showers and possible thunderstorms into southern Manitoba today into tonight. The first batch of showers will spread into southern MB this morning from North Dakota with a few mm of rain possible as the band weakens. Later today into this evening, another round of heavier showers and thunderstorms is forecast to develop over North Dakota ahead of a warm front pulling warmer and humid air south of the border. This activity is expected to push into southern MB tonight with locally heavy rain possible. General rainfall amounts of 10-20 mm are likely with this second wave, however local amounts of 20-40 mm are possible in areas that see thunderstorms.

46 comments:

  1. Once again.. GEM is the most aggressive model with precip amounts over southern MB with this next system. GEM is giving 30 mm to Winnipeg tonight, while the NAM and GFS give us 5-10 mm. Ensembles are still in the 10-20 mm range. GEM blows up an MCC complex that moves over the RRV tonight giving those heavier amounts.. so the 30 mm is based on convection. If the area of thunderstorms is further south or east, then we won't be seeing those higher amounts. Suffice to say that general rainfall of 10-20 mm is likely for Winnipeg tonight, with locally heavier amounts of 20-40 mm possible in thunderstorms.

    Whatever the case, that's quite the sharp warm front south of us with 20 degree dewpoints spreading into southeast SD and southern Minnesota.. lots of juicy air to fuel those storms later today into tonight. Best chance of severe storms for southern MB will be near the ND border tonight especially southern RRV to SE MB where large hail and heavy rain would be the main threat.

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  2. Looking like a good setup, similar to Saturday except higher Td's in the Dakotas and about 150km further west.

    Based on history so far this summer, I can't help but feel they implemented new convective schemes in the GEM-REG and that they're offering a little too much feedback to be valuable.

    I'm going with the ensemble solution for tonight, and I agree with amounts near 40mm for areas that see prolonged exposure to thunderstorms overnight.

    Also, I would not be surprised to see another monster tornado in South Dakota today; looking like an even better setup than Saturday was for them with the enhanced Td's.

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  3. Also, given the fact that the storms will likely be elevated by the time they get to us, I think their translational speeds will be too high to have very much of a risk of excessive rainfall amounts. I'd go with a slight chance of strong wind gusts for any that might be able to get across the Intl. border before midnight, and a risk of borderline-warning sized hail for a majority of the RRV, with the likelihood higher towards the 48th parallel.

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  4. Why would the weather network say rain/snow mixture on june 5, 6 and 7???? Temperatures in the mid twenties and snow!!

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  5. That makes absolutely no sense, Jewels. Although I find often when there's weather, TWN forecasts don't make a ton of sense.

    As an aside, interesting flow this morning. Noticed some waves happening this morning and I was able to catch the tail end and make a time lapse video. Check it out:

    http://vimeo.com/11992409

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  6. First batch of precip poised to move in shortly. They are forming on nose of LLJ and 850 hPa warm front ahead of next disturbance. There may be a lull in activity as LLJ consolidates to our south and intensifies this evening. Plenty of moisture and good lift from nose of LLJ and right entrance region of upper jet. Looks likely that Winnipeg will get hit by convection tonite between midnite and 4 am before precip lifts north and dry slot works in.

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  7. Severe line of storms over NW Minnesota tapping better boundary layer instability... situation could become extremely volatile over that region by late afternoon with warm front lifting in and possible clearing continuing. GFS depicts 4000 J/kg pooling along front with a 80 knots of bulk shear. Wow... watch out from Fargo NE to Sprague. Severe storms should initiate along surface warm front/ triple point - consolidating and becoming increasingly elevated as they move north, but may still remain strong especially for southern RRV as stated (maybe even Winnipeg).

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  8. NAM/GFS put SE MB under 2000J/kg of MUCAPE by 00Z. With warm front just to the south along the border, something severe could move across the border.

    I'm very interested to see what EC is thinking about this situation in their 2pm discussion.

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  9. Severe Thunderstorm Watch for Steinbach, Morden, Sprague, and Whiteshell...first of the season! As warm front moves north this afternoon and evening, we'll be in decent territory to see elevated severe storms with MUCAPE approaching 2000J/kg by evening.

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  10. I'm planning on making a timelapse of the KMVX radar today. Hopefully I'll get around to posting it later or tomorrow. It'll include warnings, hail sizes and more!

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  11. Tornado watch for much of eastern ND and NW Minnesota. Tornadic supercells possible along very sharp warm front between Grand Forks and Fargo, otherwise large hail and heavy rain with stronger cells further north.

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  12. two tornado warned cells..
    one near grafton.. north of front!

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  13. Any updates for Winnipeg? I'm starting to think we won't get any storms =(
    Will we ever get any in Winnipeg =Þ

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  14. Complex and interesting scenario unfolding... Elevated storms forming between the surface and 850 hPa warms fronts building east and down into boundary layer where low level moisture convergence is maximized. Flow trying to advect them northwards but are outrunning instability and eastward propagation appears dominant. Seems like these storms are capable of ingesting lower LCL's even as the remain relatively elevated?

    Main precip band should start retrograding back to the NW in response to nose of LLJ lifting into S Manitoba and surface warm front moving up into SE Manitoba. Will have to watch for back building lines of convection and training of cells with southerly flow thru a deep layer of the atmoshpere.

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  15. Yeah, I imagine you'll see a pretty significant diminishing of the eastward progression as the sun disappears and the storms elevate, as well as the aforementioned back-building along the jet. I'm relatively convinced that tonight will be a busier night in Winnipeg than it was on Saturday night.

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  16. Strong, well elevated cell near Carman.. motion is definitely different from the convection down in US...

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  17. Some Very heavy rain in North Dakota!!

    Hence the flash flood watch!
    Tornado warning for area's southeast of grand forks!

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  18. The lightning detector on U of M weather central website is starting to light up like a Christmas tree!

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  19. Quite the warm front.. 32C in Fargo, and 18C in Grand Forks. By the way, that strong cell over southeast MB near the border has produced over 24 mm of rain at the CWB site at Vassar.

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  20. Look at the thunderstorms starting to form ahead of the main rain band!

    Expect thunder here in Winnipeg in about a hour!

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  21. Hey everyone!

    Get ready for a deluge here in Winnipeg!

    Maybe 10-15 mm of rain in the next hour!

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  22. Once again thanks ROB Dan’ls Mark Scott etal… For the second time in 3 years I’ve changed travel plans due to your obs and Blog .and avoided extremely nasty weather. Let me explain. .Unlike the amateurs Justin n Dave are upset with I would prefer to be at home for these events if I had to choose. While traveling away from MB on family Holidaying or golfing trips I have heard those freight train coming sirens 6 times while south of the border and seen the F*nl‘s twice as many times while returning home from MN. And ND

    After spending too many occasions in the basements of MB, ND and MN Hotels, Golf club houses, Cottages and once a travel trailer , (Minneapolis weekend from hell -3 days of Tornados) I decided they find me. I needed a Heads up Display.

    As they say OBS Blog R it

    This is the second event of 4 possible that I’ve chosen not to holiday/weekend trip south and avoided the event. I misread the Petersfield (Gull Lake) warning and turned south and met it at the golf course after seeing the funnels west of Wpg Beach . Hearings not so good since then And well Minot, Estevan. To Redvers to Wpg in the intermittent dark was not a fun all-nighter a couple of years ago. Trying to cross the border after 9pm. and get home.dry and alive as they say. one out of 2 isn’t bad but eyesight is..

    So Jewels IMO this is the best source of local xt weather travel info I know. Well done ROB.

    PS Justin, recently those south central SD GPS, and Road Maps had imaginary roads and bridges on them instead of dead ends. Those amateurs would not be the first to find out the hard way. Luckily for them, not the rancher, what they drove over was someones newly planted crop and not a cliff.

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  23. THUNDER! Just heard it now in the St. James area. Woodlands radar is down, so we'll need to rely on KMVX down south.

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  24. Ya no kidding, what a coincidence. Right when thunderstorm finally reaches Winnipeg, radar shuts down!! Did it get hit by lightning? =Þ haha
    Anyways, cheers to first thunderstorm of the year (for me!)

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  25. Rainfall warning issued for south eastern Manitoba!!

    They look to get hammered with 3 inches of total rainfall amounts!

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  26. Now the Woodlands radar is back up.

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  27. As for The Weather Network's "CHRISTMAS IN JUNE!!!" prediction, wouldn't it be slightly funny if it snowed in the morning, then in the afternoon there were to be a tornado ripping through the city? Although that probably won't happen, it is still a near-impossibility!

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  28. The winds have really picked up at my place in St. James in the past few minutes!

    Gusts in around 55 km/h!

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  29. Just as I expected!

    58 km/h wind gusts at the airport!

    Can anyone tell me why the winds would pick up so much all of a sudden when it was just an area of rain that has moved out???

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  30. TAKE a look at that Squall line racing across central North Dakota!

    That squall line is racing to the north east at 50 mph!!!

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  31. Some beautiful lighting to the S and SE of my view from downtown. Looks like it might be a noisy sleep for a while tonight :)

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  32. Yeah, starting to light up to the south!

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  33. I wonder if that squall line will make it into southern Manitoba. With the 60kts LLJ nosing into our region by around 06Z, I suppose it is possible.

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  34. There was a severe thunderstorm warning issued for north Dakota heading into Manitoba that states the storm is moving north at 85 mph!!

    85 mph!!!

    Unheard of!!!
    That must mean the winds should be at least that strong right???

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  35. Wow, I am looking forward to that coming through later tonight!! (if it does, hope doesn't change direction, weaken, dissipate, all been doing that so far today)
    It looks intense though!

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  36. 85 mph? Seems rather excessive.. perhaps the storms are also building northward as they move north so it seems like they're moving faster? Whatever the case, the warning is dropped now.. with remnants of a bow echo moving through Devil's Lake ND generating 40 knot wind gusts (70 km/h)

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  37. Precip continues splitting apart and weakening before it reaches Winnipeg. Convection remains focused along NW flank of LLJ to our SE and stronger flow around upper low off to our west.

    Best chance for convection locally still looks be in the 1
    to 4 AM timeframe when LLJ consolidates and re-orients itself in favorable position. I wouldn't exactly hold my breath though...

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  38. Wow, I think it's time to batten down the hatches! Looks like this storm means business. Lots of lightning action =D

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  39. Talk about crazy, one minute its light wind and light rain falling with a bit of lightning and thunder...the next the rainfall is torrential and the winds are practically bending trees half over here. The lightning is frequent also, with loud thunder. Nuts!

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  40. Ya, i am actually surprised no warning is in place! The rain is unbelievable, double what I was expecting! Roads full of water, yard too! Thank you for this =D

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  41. I slept through the main event overnight.. got a quick 19 mm between 1 and 2 am. Must have been really tired.. I usually wake up to those heavy downpours! 26 mm total since yesterday afternoon. Looks like a general 20-30 mm across Winnipeg the past 24 hrs, with 30-50 mm over southern RRV and southeast MB.

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  42. Hey Rob!! Was there a heat burst with that thunderstorm!? I mean, the temperature was 14C at midnight, then it rose suddenly to 17C at 1 AM! Weird!

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  43. Jewels..

    No I wouldn't call that a heat burst. Heat bursts usually result in more dramatic temperature increases (like 5-10C or more) in a shorter time frame (often a few minutes), stronger wind gusts (90 km/h or more) and a notable drop in the dew point as the descending air dries (like a chinook wind)

    Last night, there was some gusty winds as the thunderstorms approached which may have mixed down some warmer air aloft. But the dew point also rose which indicates there wasn't the rapid drying associated with a descending downburst which is more characteristic of a heat burst..

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  44. Wind Warning issued for the City of Winnipeg. Any idea when this afternoon peak winds are expected before they begin to drop off?

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  45. Jon.. new blog entry added for today's winds. Should ease off later this afternoon.

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