Wednesday, July 04, 2012
Showers and thunderstorms moving through southern MB this morning
A weakening cold frontal trough pushing across southern Manitoba this morning is triggering a band of showers and thunderstorms ahead of it, bringing the first significant rainfall to the Red River valley in two weeks. Some heavier thunderstorms over southwest MB have produced tremendous rainfall totals over the Turtle Mountain area, with 80-100 mm of rain recorded in the Boissevain area, and 50-80 mm around Killarney. Storms are weakening as they head into the RRV, however some locally heavy downpours are still likely this morning, with local amounts of 15-25 mm possible in heavier showers and thunderstorms. This system will track east of the RRV this afternoon, with a return to warm and dry conditions for Thursday into the weekend.
Posted by rob at 9:15 AM
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Lightning in the Altona area this morning has been nothing short of incredible. Frequent cloud to ground strikes. Severe stuff remained just south of the border.ReplyDelete
Yesterday at supper CBC was forecasting frontal passage around 3-4 am, which explains the sunny skies icon the automated system was producing for the day. I still wonder what model they use, as all the normal guidance was indicating showers starting much later in the morning (what's actually happening). Anyone know what model they use?ReplyDelete
Not harping, just trying to understand how my tax dollars are being spent.
Couldn't tell you...the GEM-REG, GEM-GLB, NAM, GFS and RUC all had the stuff coming through mid-morning/early-afternoon. Didn't check the UKMET model, but I'd highly doubt they'd be using that.
I'm pretty sure John Sauder at CBC subscribes to an American weather data provider... so model data would likely be from the NAM. As Brad mentioned, most guidance, including the NAM, had frontal passage around midday today.. although NAM may have been bringing precip in earlier.ReplyDelete
The NAM makes sense if CBC is using using an American provider for their data, but I checked the NAM yesterday and it was pretty much in line with the other models for the precip timing as Brad says. I also checked the UKMET and it indicated showers as well later in the morning. Maybe he was using an older model run. Oh well.ReplyDelete
Strong winds heading for Winnipeg in the next few minutes?ReplyDelete
Nice line of training cells just north of Carman heading northeast towards Winnipeg. If it holds together, we could be seeing some thunderstorms with heavy downpours here within the hour.ReplyDelete
Line sliding just south of the city.. LooksReplyDelete
Ike we're going to miss heaviest activity here.
That sucks. No surprise though.ReplyDelete
Gusts of wind in St. James, looks like the front it finally passing through the city.ReplyDelete
Can anyone confirm that the front has passed yet? My guess is that line just about to hit the city is the front, but I cannot confirm.ReplyDelete
Storms are firing south of Winnipeg. Threat is not over yet.ReplyDelete
The depressingly long drought beginsReplyDelete
Well CBC wasn't that bad, it's quite sunny now.ReplyDelete
Tough break for you guys. A couple batches just missed to the south. Not much more that can be said.ReplyDelete
Maybe next month lolReplyDelete
Nose of LLJ just a little bit too far south with that elevated complex earlier today.ReplyDelete
Note that surface low is still just to our south with backing easterly winds nearby. There is some chance for surface based connvection to pop north of the low, where moisture convergnece is maximized. Instability present as is good deep shear..
So is that it for Thunderstorm Development Today?ReplyDelete
That's it for the next 2 weeks I thinkReplyDelete
Well, What they say is that summer is all about the heat and dry weather. The other half of the Summer is about Storms. I guess I'll have to take whatever we get.ReplyDelete
This is probably it for the next month imo :PReplyDelete
It is what is!ReplyDelete
Downright depressing anyways! It's bad for everyone since we rely on summertime thunderstorms mainly for our rainfall. Lack of thunderstorms= dry summer almost always.ReplyDelete
Cumulus field developing along inverted trough north of the low.. our last shot at some convection today.ReplyDelete
Clouds are elevated altocummulus.. too much subsidence in the wake of that complex that moved thru around midday. Put a lid on vertical development even with good instability and convergence.ReplyDelete
Had a good chance of seeing some heavy rain today in Winnipeg, but as noted, bulk of it passed just south of he city with up to 16 mm in Sanford reported. Only about 4-5 mm here in Winnipeg, but potential was there for a good 15-25 mm today. Now it's back to the dry spell ove the next week or two, although we should still see some chances during that time. Seems like its feast or famine around here when it comes to rain.ReplyDelete
Quite the storm in Windsor this evening. After hitting 38c (46 humidex) they got hammered with a torrential thunderstorm that dropped hail, wind gusts to 80 kmh, and 54 mm of rain in just over an hour. Now THAT'S a storm!ReplyDelete
I'm hesitant to say that the cold front has actually passed through the city. By all accounts, it was merely a trough that brought the storms through earlier this morning. The only thing that would really hint at a cold front was the rising pressures, but by definition you get that behind a trough as well.ReplyDelete
Still got up to nearly 30°C today, dew points remained 21-23°C through the afternoon and evening, and we had pretty much no wind save for a few gusts here and there while convection was going on.
Main dewpoint drops and organized westerly winds are just now entering the Red River Valley. Dewpoints currently sit at 23°C in Winnipeg, 15°C at the Deerwood station, and 13°C west of the escarpment. CU field associated with a surface feature/wind shift was evident through much of the afternoon slowly advancing eastwards as well.
Always hard to tell what to call some weather features. If it -was- a cold front that passed through this morning...well that was one of the weakest cold fronts I've ever seen in my life. I'm going to go with calling the feature passing through the RRV right now the cold front and this morning's action just a trough :)
Finally seeing a good line of towering cumulus, but its a case of too little, too late.ReplyDelete
Yeah we've been alternating between unsettled and droughty patterns since March, as the mean position of the upper ridge shifts west and east.
The storms this morning were associated with the nose of the LLJ as it moved east. They generated enough outflow to produce a wind shift line out ahead of them. As the afternoon worn on however, the synoptic wind field reasserted itself.
37.9C in Windsor today. Warmest temperature recorded in 2012 in Canada.ReplyDelete
A 26.3C dewpoint was registered in London, Ontario a record for this year as well.
Finally, Windsor had a humidex of 46C today, the highest it has gone this year in Canada.
Huge t-storms in Windsor and Montreal today... What a day in Eastern Canada.
A refreshing change out there today with breezy and noticeably less humid conditions.. dewpoints down to 11C in Winnipeg compared to the 20C+ values of the past few days. With sunshine and 27C temperatures this afternoon.. ideal weather on tap today especially for those looking for a break for the heat and humidity. (5 straight days of 30c+ at my site)ReplyDelete
Models showing an MCS type system blowing up over North Dakota late today into tonight with heavy rainfall possible.. but staying mainly south of the border, perhaps grazing far southern RRV. Another chance of showers or thunderstorms Saturday mainly through the Interlake as a weak trough passes through, and then it's back to sunshine and building heat for next week. In fact, ensembles are hinting at some major heat pushing into southern MB by middle to end of next week (July 10-15 time frame) with highs of 30-35C possible.
It almost even felt chilly this morning. Gotten too used to the humidity..ReplyDelete
I see that system on the precip model in ND. How do they figure they'll get all that? Seems like there isn't much in the way of synoptics in terms of lows or troughs to produce such high amounts of precipitation, other then a bit of a shortwave at 500mb, and a broad 1008 mb sfc low just to the south. Is that just enough to trigger such a system? Thats the only place in the whole country seeing any type of low so maybe even though its not a very deep low at 1008mb, because its by itself it has nothing to compete with and has un restricted access to gulf moisture I'm guessing?ReplyDelete
You mentioned decent heat coming our way by the middle of next week with temps of 30C-35C possible.
Do you think that there is chance of seeing temps rising above 35C given all the heat that's in place south of the border?
Adam... Looks like a good setup for elevated storms tonight over southern and central ND, with 45 kt southerly 850 jet tapping 15-20C low level dewpoints. Such setups can often result in west-east bands of training thunderstorms that can result in heavy rain over a narrow swath, even with a modest surface low. GFK notes that 25-75 mm is possible over southern ND with some hi-res models indicating localized amounts of 75-125 mm. That's according to the models... we'll have to see if and where this elevated convection fires up, which is not always a given. But the potential is there.ReplyDelete
Anon... Absolutely. Given the widespread heat south of the border, and the fact that we're approaching the climatogically hottest time of the year over southern MB (mid July), I think it's quite possible that we could be seeing temps over 35c by the end of next week..ReplyDelete
I need to read up more on elevated storms and how they work, as it appears they're the type of storms to defy some odds when developing, such as a lack of forcing from synoptic systems, as well as a lack of instability indices (positive LI's and negative CAPE are forecasted for the area of ND expected to see the most activity in terms of falling precipitation). I understand that indices such as CAPE and LI pertain more towards the development of air mass and severe thunderstorms in an unstable environment I just don't understand in this case how only one parameter, the LLJ can contribute to so much moisture developing when everything else seems to be lacking. Thunderstorms are so finicky and sometimes it seems they need all planets aligned to form (at least in Winnipeg anyways). I would figure there would need to be a little bit more than a LLJ to get this much organized convection going, which I can't see anywhere on a chart or graph, other than a weak shortwave at 500mb and a subtle surface low that don't look threatening enough to produce all that rain. Something’s happening that I can't see too well anyways.ReplyDelete
NAM and GFS do show some negative LI's and positive CAPE (whereas the GEM showed positive LI and negative CAPE) but not very much.ReplyDelete
They are also expecting a lot of frontogeneisis and deformation north of the low track.. along with something called symmetric instability, it often leads to embedded convection and banding north of where most of the surface and elevated instability are.ReplyDelete
Adam.. Traditional convective indeces like LI and SBCAPE don't work well with elevated convection, since they're surface based indeces, and elevated convection is rooted generally above 900 mb. Indeces like Showalter (SI) and MUCAPE (most unstable CAPE) would give a better indication of the degree on instability aloft. Note also that elevated convection is most favourable when you have a sharp north-south temperature and dewpoint gradient, with a southerly jet riding over the warm front, generating the lift to initiate elevated convection.ReplyDelete
The best focus for that type of activity in tonight's case is over southern ND with 20C dewpoints over SD and single digit TDs in ND. NAM on the other hand shows most of the rain over northern ND while GEM shows heaviest QPF over SW ND which looks a little more plausible.. Just starting to see some tstorms fire up now over the western Dakotas with SPC showing a slight risk of severe over SD. We'll see how things develop into this evening and overnight..
19Z HRRR (often quite accurate in projecting precipitation fields), is quite aggressive with an area of light rain reaching Winnipeg by around 2 am. The model also shows MCS tracking along far southern N Dakota, with the nose of the LLJ at the N Dakota and S Dakota border.ReplyDelete
Rob,Brad Rousseau is hinting at another severe weather event for Southern Saskatchewan Tomorrow and another MCS moving through our region Overnight into Saturday Afternoon.ReplyDelete
What do you think of this potential? considering it has been an active storm season for those in Saskatchewan, and the fact we already have seen a few MCS roll through
These charts help a bit understanding the elevated convection.ReplyDelete
(or click my name)
Lots of altocumuulus and altostratus around with radar returns already reaching Morden area. Dewpoints are in the mid to upper teens so some light shower activity should be reaching the ground.ReplyDelete
Precipitation looks like it will organize into two main regions overnite.. with a band arching from the SW corner of Manitoba up thru Winnipeg and the interlake. It looks to be associated with 850 hPa frontogenesis.
Main show will be MCS that will move along the interstate 94 corridor from Bismarck to Fargo.. it will be associated with nose of LLJ and elevated instability.