A line of thunderstorms ahead of a warm front produced heavy rain across the northern Red River valley Friday morning. The storms rolled into Winnipeg about 5 am and continued through much of the morning, dumping 25 to 40 mm of rain across the city by 10 am. A lightning strike even knocked off part of a church tower downtown around 6:45 am. The line of thunderstorms settled just south of the city between 8 and 10 am, dumping heavy rains of 50 to 80 mm from Elm Creek through Starbuck and La Salle to Landmark. (see map below) The showers and thunderstorms this morning are a prelude to what is expected to be a wet weekend over the Red River valley with additional showers and thunderstorms through Saturday into Sunday that threatens more heavy rain. This will elevate local flooding concerns if the heaviest rainfall occurs in areas already hit hard by heavy rain today.
Map showing rainfall amounts (in mm) from Weatherbug network as of 10:30 amHighest rainfall totals Friday morning from Weatherbug and Manitoba Agriculture networks..
Glenlea.......... 78 mm
Landmark......71 mm
Elm Creek.......63 mm
La Salle...........62 mm
Sanford.........61 mm
St Adolphe........56 mm
Starbuck.........55 mm
37 mm total at my site. Online station only reported 10 mm due to blockage and sheltering of the gauge by leaves of a nearby tree.
ReplyDeleteSevere-looking cells popping up now South of Carman. Should a severe thunderstorm watch/warnings be expected for some areas?
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ReplyDeleteSevere Thunderstorm Watches and Warnings out now, answers my question.
ReplyDeleteA little late, but I measured 40 mm this morning =D
ReplyDeleteI'm excited for more!
Strange scenario ongoing... YWG reporting SSE flow for several hours. Seems to be induced from mixing and outflow of convection along int'l border. Synoptic warm front appears to be hung up south of Grand Forks on other side of precip band. I have never seen this kind of 'pseudo warm front' before .. I suspect it is unusual?
ReplyDeleteIts too bad Environment Canada does not have any Flash Flood watches that it can issue as they would certainly be warranted in tonite. Region of maximum convergence from LLJ and 850 hPa theta e ridge remain nearly stationary again tonite with PWATs (precipitable water) of 40 to 50 mm. Expect band of heavy convective precip to consolilate and orient itself along WSW to ENE line somewhere over our region tonite (I would say anywhere from Winnipeg to Grand Forks).
Outflow will continue to play havoc with position of warm front tomorrow making it hard to anticipate where warm sector will set up. If convective debris can clear out, things may get very unstable by the time cold front comes thru.
PS.. dissapointingly there is no mention of heavy rain potential in today's focn45.
ReplyDeleteMost important question of the day: What time should I get to bed so I'm not exhausted tomorrow? Hmmm...will I be woken up at 5AM again or not?
ReplyDeleteHmmm...
If you believe the GEM, south-central Manitoba could be in for a decent surfaced-based severe weather outbreak tomorrow afternoon. The GEM is showing 2000 to 3000J/kg of SBCAPE for that area by late tomorrow afternoon. This would be the combination of tds in the 16 to 20C range and temperatures in the high twenties.
ReplyDeleteFrankly, I'm quite skeptical of this solution. I think the dewpoints that are being advertised are reasonable, given that the td is already 16C at my house this evening. However, getting temperatures to approach 30C would require the warm front to lift north to the Trans-Canada highway. With the warm front to the north, we would need good clearing over the RRV to provide sufficient insolation. While this isn't impossible, I think it may be a long-shot. While I would really like to see a good severe weather outbreak, I'm not to get my hopes up again, just to see them coming crashing down alongside EC's overly warm high temperatures (sorry had to add that in there...Steinbach's forecast high today was 30C, actual high was 20C).
As Brad mentioned, forecasting convective precipitation is one of the most challenging and difficult forecast challenges meteorologists face. Models are fairly good in pointing to the potential for heavy convective rainfall, but they are notoriously bad in predicting exactly where and how much will fall. It's pretty much a short term forecast once you see the cells develop, then you have a better idea of exactly where the heaviest axis of rain may set up. Even then, it's often a fairly narrow axis in the grand scheme of meteorological scale, which makes forecasting it with a lot of lead time that much more difficult. Personally, I'd like to see a "Heavy Rain Watch" or "Flash Flood Watch" issued for a general area which would at least prepare people for the potential of heavy rainfall. Then more specific heavy rain warnings could be issued for smaller scale regions once we have a better idea of where the bands are setting up. Seeing 10-15 mm in the forecast just doesn't prepare you when you get 50-80 mm.
ReplyDeleteSo, with all that being said, what may Winnipeg expect tonight through Sunday? Well, the set up is similar to yesterday with the sharp warm front along the MB/ND border, and a good 850 mb transport of warm air and moisture north of the front. The models hint that the best forcing will be a little further north than this morning's activity, which would displace the axis of heaviest rainfall to the north of today.. possibly from Dauphin through Gimli into the Whiteshell area (in fact, latest radar hints at some development starting south of Dauphin this evening). Winnipeg may still see some overnight showers and thunderstorms, but perhaps more short lived than this morning's activity, so not as much overall rain (though downpours are certainly possible) Things get interesting for late Saturday into Saturday night with models blowing up more convection over southern MB as the main low and cold frontal trough push through the eastern Dakotas (where there is more likely a threat of severe storms) Modes hint at very heavy rain during this time with 50-75 mm possible in some areas. The whole mess moves off Sunday with lingering wrap around showers. So all in all, I figure maybe another 10-20 mm overnight into Saturday morning, then another 15-25 mm Saturday night (with potential for a lot more), and another 5-10 mm Sunday for a 30-50 mm weekend total. Still a tough call to make.. and judging by the spread in the poll numbers, I'm not alone!
What is the protocol for Flash and overland flood warnings?
ReplyDeleteAre they produced by EC or the province and who are they sent to.?
MB Water Stewardship included them in a long post with similar Weekend QPF totals at 2pm this afternoon
The present storm system has brought ....... Some flash flooding is already underway in these (La Salle and Seine River) watersheds. ...Additional heavy rain of 25 to 40 mm is expected over much of southern Manitoba this Saturday and Sunday, with 50 to 70 mm possible over the Red River Valley from Emerson to Winnipeg and eastern Manitoba.
MBWS went on to indicate general Overland, Flash and Overbank River flooding warnings.
The rain is falling on soils already near saturation from heavy rain on the Victoria Day long weekend. As a result much runoff is occurring and this will increase as additional precipitation falls. This will result in overland flooding with overtopping of ditches and smaller streams and rapid river rises.
If it occurs (yours or their QPF forecast) RR levels are predicted to return to near spring peaks by June 5
Jim..
ReplyDeleteEC issues warnings for severe thunderstorms that will poduce heavy rainfall rates of 50 mm/hr or 75 mm/3 hrs. We don't really have a "flash flood" warning per say, but the severe thunderstorm warning will highlight the threat of heavy rain, which implies the problems associated with heavy rain including localized overland or flash flooding.
Once rainfall becomes a problem with rivers or streams overflowing their banks, then it becomes a provincial responsibility to issue high river or stream flow warnings that will cause flooding concerns. The province will often seek input from EC to get input on rainfall totals and projections in these cases.
Nice line of storms over SW MB moving this way. Brandon reported a 55 kt (100 km/h) wind gust as the line went through. Several smaller cells popping up just west of Winnipeg ahead of that main line.. so looks like things will be getting wet (and noisy) again around here soon.
ReplyDeleteThanks Rob..The RR is already over its bank in Ft Garry at 530 this am (dog walking detours are back) Pony Corral Lower Parking lot is starting to be flooded. Their dock is about to join the rest of the Flotsam heading north.
ReplyDeleteAnd that is Hail I hear on the quarterdeck.
Severe Thunderstorm Watch just issued for Winnipeg, warnings are looking imminnent
ReplyDeleteGust front north of Portage has winds up to 130km/h now. Expect that near-warning winds will head through Winnipeg in 30-60 minutes.
ReplyDeleteReally an interesting morning, given that the nocturnal convection usually dies once the sun comes up...
Scratch that, winds are wrapping behind the gust front and reconsolidating. Gust front moving into the Gimli-Selkirk area at with wind speeds up to 70-75 knots.
ReplyDeleteAnd I'm a little concerned what might happen when those winds hit the Woodlands radar site...
ReplyDeleteExperience shows that usually wind doesn't adversely affect Woodlands RADAR, at least not 75 knots. Back in 2005 a wind of just over 80 knots hit the RADAR site and it was knocked out for a while, but not by the wind; it was the lightning that knocked it out. Time will tell.
ReplyDeleteShould be a warning for Winnipeg right now in my opinion. For rain. Any rain that is capable of almost filling my window well and flooding my basement is worth a warning!
ReplyDeleteAll the streets and parking lots in my area are completely flooded. There's cars half underwater here.
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ReplyDeleteJon,
ReplyDeleteCan you get in touch with me at b v r o l i j k [at] g m a i l . c o m
Thanks :) (No spaces in that address, obviously)
In the last two days of tstms, I've received 64.2mm of pcpn, which is more than the avg rainfall for May (58.8mm). I pray my basement does not leak - my house is up for sale next week!
ReplyDeleteOmg Jon, if that's true, I think someone is underestimating this thunderstorms, since there's no warning. But, AHA! a warning has finally been issued, maybe a bit too late =Þ
ReplyDeleteI had marble to dime sized hail at my place at about 8:25am this morning.
ReplyDeleteLooks like a good setup for storms this evening in south-central and south-eastern Manitoba. All the models bring temperatures in the high twenties/near thirty, to the RRV and points nearby. Tds are forecast to rise toward 20C by evening, which creates SBCAPE values over 1500j/kg in a large area. LLJ of 40kts is forecast to develop by 00Z along with 40kts of deep shear. This creates EHI values of 3 to 4.
Since all the models agree on temperature and moisture I have to believe them. However, we need to ensure the cloud cover dissipates, otherwise temperatures won't climb high enough to give us a good surface-based threat.
Good start to the Wknd but we could use a few more choices 75 to 100, 100 to 150, and >150 come to mind...lol
ReplyDeleteI have my doubts about the surface temperatures today; lots of cloud about and the last 2 days models have been a little optimistic on our temps by as much as 10 degrees.
ReplyDelete70 mm since yesterday night here! Yard flooded all around my house almost, this morning. Taking long time to go away too, ground's saturated!
ReplyDelete139.4 mm of rain so far this May here, more to come probably?
Temperatures are beginning to rise in south-central and south-eastern Manitoba as cloud cover breaks apart. Temperatures are generally in the +22 to +26C range with tds around 16C. Temperatures are forecast to increase into the high twenties by late afternoon.
ReplyDeleteWell looks like we got a break in the action this afternoon. So back stroked my way to my rain gauge and total rainfall from Thursday evening to 1 PM today was 54.8 mm here in east Charleswood. The bulk of this rain came in two dumps generally between 5 and 10 AM on Friday and 7 and 10 AM this morning. Looks like we are priming ourselves up for another round of heavy rain/thunderstorms this evening into Sunday morning. That should help settle the dust down.
ReplyDeleteLatest RUC (18Z) puts very high EHI values over the RRV this evening. CAPE of 1500 to 3000J/kg and EHI of 3 to 6 will provide a slight tornado risk.
ReplyDeleteLooks as though some clearing/ warm sector may back into Winnipeg by mid to late afternoon. LLJ retrogrades back to west a bit ahead of main disturbance so elevated storms firing from Minot up thru Gimli should remain off to our NW. That could make things interesting as line of surface based storms get going along front especially for St Adolphe/Glenlea areas and SE.
ReplyDeleteSeriously, like why does the radar always work badly, and shut down from time to time during thunderstorm events? Annoying..
ReplyDeleteHere comes round 3! Storms forming along crest of wave and warm front over southern MB tapping very warm and moist air just to our south. As Scott mentioned, 25C temperatures have crept into southeast Manitoba with 30-35C temperatures in North Dakota! The storms forming over us have a potential for heavy rainfall once again with west-east orientation and training cells.. Rainfall rates of 10-20 mm/hour under heavier cells so look for another east-west band of 20-40 mm with locally higher amounts possible this afternoon into tonight. Not good for Winnipeg and northern RRV which are saturated from past two days of heavy rain. Ditches are at bankful here in Charleswood and any more rain will likely bring water over roads in some areas. Look for potential of severe storms forming over southern RRV and SE MB along cold frontal trough tapping juicier airmass with large hail and damaging winds the main threat, but potential for some tornadic supercells given decent low level shear and outflow boundaries to work with. Dave C. is in northern ND chasing and you can follow his blog to see what he encounters. Could be an interesting few hours coming up..
ReplyDeleteWe will have to watch the storms forming on southern edge of line to see if they can become surface based... while driving to U of M.. spotted ill defined wall cloud/ inflow feature on cell that just blew up over NE Winnipeg... more cells about to pop and move into the city. Outflow has nudged winds back to NE but will have to see if storms can ingest low level SE flow and instability as they try to build into boundary layer.
ReplyDeleteI have my doubts as to any SE flow showing up again; winds are pretty much between E and N all the way to the international border. A few small cells are now firing off in the Pembina region of North Dakota near the warm front; it'll be interesting to see what they decide to do.
ReplyDeleteInteresting indeed.. those cells are in a good shear environment with high CAPE.. Note that Woodlands radar may be underestimating radar returns right now due to attentuation with heavy rain over the radar site. Rainfall rates of 15-25 mm/hr being observed in that band just west and north of the city..
ReplyDeleteRob
ReplyDeleteIs this early evening round mainly going to miss Winnipeg and is there another round later that will hit Winnipeg? It looks like most of it is missing Winnipeg by just a few miles to the north.
Storm right near the border should definately have a warning. RADAR indicates that hail of golf ball size is possible...plus there is a warning on it just across the border.
ReplyDeleteDaryl.. Judging by the latest radar loop, it looks like this band will gradually build southward into Winnipeg over the next hour or so.. so I would expect some heavy rain this evening before the line weakens..perhaps another 20-30 mm judging by the rainfall rates upstream with potentially higher amounts if the intensity maintains itself.
ReplyDeleteUnexpected: 102km/h gust at YWG. That was fun :)
ReplyDeleteWind gust of 55kts at the winnipeg airport.
ReplyDeleteWow is it ever raining on the north side of Winnipeg right now. I think the totals by tomorrow will be over 100 mm
ReplyDeleteDaryl - I agree. I already have a storm total of 84mm, and there is plenty more to come.
ReplyDeleteExtreme precip rates associated with complex developing along surface warm front off to our south as they tap all that surface based (or just off the surface) instability. Our precip band seem to be supported by convergence from LLJ... in the short term, southern band tapping better instability will likely start cutting off moisture supply to northern line... but everything could merge into potentially massive complex as soon as sun goes down and LLJ cranks up again.
ReplyDeleteWe caught a few beautiful shelf clouds here around Grand Forks. Outflow-dominant storms today, but very beautiful. Tomorrow looks like mainly a travel day, but perhaps a marginal day in south-central Kansas. The next couple of days will be over western Kansas and eastern Colorado. I'll have a roundup later today. Or early tomorrow morning.
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