Wednesday, June 06, 2012
Next threat of thunderstorms moves into RRV Thursday evening
A trough of low pressure moving across southern Manitoba Thursday is forecast to produce an area of showers and thunderstorms over southwest MB by afternoon, likely spreading into the Red River valley by evening before weakening east of the valley Thursday night. The storms are not likely to be that severe owing to the lack of strong wind shear, however adequate moisture and instability will likely trigger a few strong storms with a slight risk of nickel size hail. More likely, the storms will produce locally heavy rainfall with local amounts of 25 to 50 mm possible, especially over western MB into the Interlake region. This band of showers and thunderstorms will gradually push through the Red River valley Thursday night into Friday, with a gradual drying trend by Friday afternoon. More unsettled weather with showers and thunderstorms is expected Saturday night into Sunday over the RRV, with a potential for some locally strong to severe thunderstorms.
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Latest runs of the NAM paint a potentially ominous picture for southern Manitoba. They show a warm front lying from west to east, near the US border. Lots of instability and moisture to work with. Lifting mechanism looks good and there is a decent amount of shear, as well.
ReplyDeleteGFS is a bit further west but also shows good potential for strong to severe storms on Saturday.
Both models have 2,000+ J/KG of MLCAPE remaining in place overnight on Saturday. We might have a supercell threat along the warm front on Saturday followed by an MCS of some sort on Saturday night with the surging cold front. Could be fun!
Sunday starting to look pretty interesting as well. Probably wouldn't be a good idea to be in a tent camping this weekend, especially South RRV.
ReplyDeleteGood point. I see the GFS continues to show around 2,000 J/KG of MLCAPE at noon on Sunday. Could be some re-generating convection in parts of southern MB during the day Sunday.
ReplyDeleteCampers beware this weekend, especially Saturday night into Sunday!
Any threat for thunderstorm this eve?
ReplyDeleteIt definitely pales in comparison to the potential on Saturday. There will be some instability (1,000-2,000 J/KG of MLCAPE) to work with through the evening. The shear is nowhere to be found, however. Looks like we can expect a band of showers and thunderstorms to develop later this afternoon and slowly move towards the RRV. Main threat is heavy rain. Could be a decent lightning show if things pan out.
ReplyDeleteRe tonite..
ReplyDeleteNote that models are trending slower with the evolution of the is system. Initailly, convection should be focused where mositure convergence is maximized around a closed 850 hPa low tracking up to Riding Mtn. Another area of showers/tshowers may form on the nose of the LLJ down over N Dakota or central Minnesota.
Between the two areas ther will be very weak shear and forcing. However, due to the slower progression, precip may start to fill in early tomorrow morning along the main moisture axis, as trowal becomes better organized. Showers may linger until at least midday, with surface trough not coming thru till around 3 pm as per the American guidance. With strong blocking pattern, I feel RGEM SCRIBE is too early in pushing dry slot thru.
Re Saturday..
Given the slower motion of the first system, it raises uncertainty regarding timing for the main disturbance. Yes, the 12Z NAM sceanrio is scary for extreme SW Manitoba with 50 kt deep shear, good low level shear around the warm front, and extreme instability. Cap weakens in northern tier of counties across N Dakota by around 7 PM. Winnipeg would see generally an elevated threat as cells merge and move north later.
However, there are also still huge differences in surface pressure pattern between GFS and NAM. As mentioned before, this is due to the potential phasing/ interaction between the northern and southern streams. This is manifested in the large differences seen by Sunday. WIth NAM more progressive and showing more splitting between the LLJ and main upper trough, while the GFS is slower with more phasing. GFS solutions would keep the chance for elevated convection goign thru Sunday.
Daniel
I was wondering about those differences between NAM and GFS. GEM seems to be right out in left field. Thanks Daniel for the explanation, very helpful.
ReplyDeleteLots of storms in North Dakota and slowly pushing north. Strong to severe stuff approaching SW MB.
ReplyDeleteWe'll see how the stuff further east does. There's a couple of outflow boundaries surging ahead of the main band of storms and helping to re-generate convection. Fun to watch.
Hey..Just wondering sbout the storms that are coming up from north dakota..Will winnipeg see severe weather tonight? or will these storms weaken before they affect us..
ReplyDeleteGood burst of rain for 5 minutes here in Westwood at 5:50PM Friday. The shower moved NE quickly. Approx 4mm
ReplyDeleteChris Gartner - Carroll Road (Westwood)
Theres some very impressive looking cells near the manitoba border..but theres no warning on them...weird..
ReplyDeleteAnonymous.. Thunderstorms over SW MB mainly heavy rain producers right now.. Radar indicating more of a hail or wind threat in North Dakota but cells seem to weaken as they head across the border into MB. Still could be some severe cells crossing the border this evening with hail or wind, but storms will mainly evolve into a heavy rain threat tonight into Friday morning with very moist airmass (pcptl waters running 30-40 mm) and slack flow. Also remember that Foxwarren radar is running hot which makes radar returns seem much stronger than they really are over SW MB.
ReplyDeleteBy the way, Winnipeg airport's first official 30C of the year today with a high of exactly 30.0C this afternoon.
ReplyDeleteRob,
ReplyDeleteQuestion...
With all the talk of severe weather and possible tornadoes on Sarurday, what's your take on this possible stormy day and does Winnipeg have any chance of severe weather Saturday? Also, any heavy rain threats and flash flooding possible with this event as well?
Storms in SW MB and N ND are producing a pretty good amount of lightning. Activity continues to re-generate to our south. Could be in for a nice lightning show tonight.
ReplyDeleteSurprised to see how the storms are increasing in intensity, a lot of lightning in these. A lightning show is pretty certain with the way things are going now....
ReplyDeleteAnonymous.. Yes, I think Winnipeg has a threat of severe thunderstorms Saturday evening, but the better setup for severe storms will be southwest of Winnipeg along the Hwy 3 corridor from Killarney through Pilot Mound to Morden/Winkler areas closer to the warm front. If RGEM model is right, that area will see dewpoints in the 18-20C range by Saturdya afternoon, with CAPES of 2000-2500 j/kg and very favourable veering wind profiles. Supercells likely given these parameters with large hail and wind threat along with possible tornadoes. Storms will then continue northeast into Winnipeg and northern RRV Saturday evening, with some severe storms possible but likely not as severe as further south. Should be an interesting day. Note that SPC is thinking that model dewpoints are overdone for Saturday, which would give lower instability values but still a severe threat for hail and winds.
ReplyDeleteRob,
ReplyDeleteDo you think today's forecast high of 27C is very optimistic given cloud cover and rainfall this morning? Note that yesterday the forecast for today was a cooler 22C
Thanks for the heads up on the possible severe weather threat. It seems as there is still some uncertainty regarding this event on Saturday and perhaps into Sunday
Looks like a pretty good potential chasing day Saturday...Brad has awesome briefing of what may unfold Saturday, and it generally appears that the tornado threat will stay mainly to the southwest of Winnipeg...regardless of model differences that are still in place looks a very stormy end to Saturday throughout the province
ReplyDeleteLooking forward to see what the latest NAM and GFS runs from today indicate. Personally I am trending towards the slower GFS solution but time will tell i guess
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