Wednesday, May 23, 2012
Major cooldown for Friday and Saturday.. Snow possible for western MB Thursday night? Frost possible Saturday morning over RRV.
Enjoy the 20C temperatures today.. because it will likely be a while before we see temperatures that high again over most of southern MB. A low pressure system crossing southern Manitoba on Thursday will drag a cold front across the regions later Thursday into Thursday evening, ushering in a much cooler airmass from the north. Showers behind the front Thursday evening may even mix with or change to.. (yikes!) snow.. over higher elevations of western MB Thursday night into early Friday. Friday will be an unseasonably cool day across southern MB with mainly cloudy skies and temperatures only around 10C for daytime highs.. over 10C below normal for late May. Skies are expected to partially clear Friday night, which will bring the potential for frost across much of southern MB including Winnipeg by early Saturday morning. Gardeners beware. Saturday should be dry for the most part, but another major system moving out of the American south will push a warm front into the Dakotas, triggering another round of showers and thunderstorms Saturday night into Sunday over southern MB, with the potential for locally heavy rainfall yet again. Generally dry but cool weather is expected into the first part of next week before a warming trend later in the week.
Posted by rob at 3:49 PM
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I noticed the GEM is quite a bit wetter over nrn ND than the american models daytime Saturday. Expect a tight gradient over northern ND/MN and southern Manitoba from sun to clouds and rain. Sunday does look wet over southern MB however.ReplyDelete
A non-related question Rob or anyone else. I saw a question on an American travel/weather forum about sunshine hour/minute measurements in Canada. I see they are available in the normals... but did know if sunshine hours/minutes are being measured currently by EC. In the U.S. NWS no longer has any sunshine units.
Dan.. as far as I know, sunshine data is no longer measured at EC sites. In Winnipeg, sunshine data stopped in 1997. Kind of odd that sunshine data is no longer recorded, even though the UV index is now a standard part of the forecast.ReplyDelete
Thanks Rob for the response.ReplyDelete
Noticed that the Norwegian web site has been considerably cooler for Winnipeg. At one point, earlier in the week, EC was calling for 18c for Friday while yr.no was saying 7c. EC has since dropped to 11c. Any idea what model the yr.no site uses?ReplyDelete
What do people expect in general for summer 2012 in the prairies? I keep reading that we're in for a "scorcher" of a summer, but it'd be nice to get a little more extended commentary. I'll be in Winnipeg between late July and early August, and taking a road trip to Jasper, Alberta, during that time as well. I know long-range forecasts are a bit of a fool's game, really, but I just wonder *how* hot people expect it to get. Any comments on precipitation, storm activity, or anything else deemed relevant would be nice too. And of course, I'll keep in mind that these are general comments rather than a forecast for my trip. ;PReplyDelete
I think the Norwegian yr.no site uses ECMWF data.. but I'm not positive. Definitely some European model..ReplyDelete
Here comes the cooler air.. cold front just pushing through Winnipeg/RRV now with cloudy skies, northwest winds and occasional drizzle to our west. Portage down to 10C in drizzle right now, Brandon 6C in drizzle, Dauphin 4C in rain, and The Pas is +1C with a mix of rain and wet snow!ReplyDelete
The best "forecast" of the kind of weather you may expect in a few months from now is to take a look at what the average weather is like during that time. Long range outlooks that far ahead have very limited accuracy, especially in the summer when weather is highly influenced by smaller scale convective processes.
Normal highs in Winnipeg in late July/early August are around 26C with lows of 13C.. but record daytime highs range from 35-38C during that time, with record nighttime lows of +4-7C. Days in late July can be quite humid, with humidex values sometimes reaching 40 or more. Statistically, there's a 33% chance of measurable rain on any given day, usually short lived showers or thunderstorms, which could be heavy or severe at times.
For what it's worth, NOAA is non-commital on the kind of summer we'll have in the southern Prairies, showing an equal chance of near, below or above normal temperatures. They show a better chance of warmer than normal temperatures over the SW US. EC's summer outlook is showing warmer than normal temperatures across much of the country, including the Prairies. But I don't put a lot of faith in those forecasts which are completely computer generated and have less than 50% forecast skill over the Prairies.
With the next 4 or 5 days looking pretty dreary and cool, will we possibly see our first month of below seasonal average?ReplyDelete
Re frost potential..ReplyDelete
We have a couple lines of defense possibly mitigating frost potenial Friday night.. one will be an area of low clouds that most models hint will break up, but some may hold on especially in the southern RRV. Second are higher level clouds (between 300-500 hPa), that may stream associated with a strong jet stream aloft by around 3 or 4 am. Also, atleast some moderation can be expected as the ridge moves east and is affected by low level heat and moisture flux from the ground. Hopefully one of these will come thru..
Re weekend precipitation..
Chances for significant precipitation dont seem particularly great looking at latest NAM. Bet you could of guessed that another split is being suggested. Best chance for heavier precipition will be if we get brushed by a complex associated with the nose of a strong LLJ focused over the eastern dakotas and Minnesota. Deformation zone associated with parent trough will set up off to our NW.. potentially putting us in the dry slot. Models hint at more convection firing off as trailing disturbances move up in SW flow over the Dakotas to our SE late Sunday.
As of yesterday, the mean temperature at Winnipeg airport was 13.2C, or 1.2C above the normal May average of 12.0C. Based on current forecasts, looks like we could lose about 0.5 degree C or so off that average by the end of the month, which would still keep us a bit above normal. But it just depends on how cool we are over the next 5 days. We're currently on a 10 month streak of above normal monthly temperatures going back to last July.
yr.no now has a high of 5c for Friday, EC 9c. Will likely be in the same air mass as The Pas, Norway House and Swan River on Friday. The Pas managed to get to 10c after breaking into sunshine late in the day. While Swan River and Norway House peaked at around 2 to 5c under precipitation. Place your bets will we stay above normal?ReplyDelete
Anonymous... I don't agree with your forecast for precipitation on the weekend. Forecasters from the NWS in Grand forks are pinpointing that areas along the American border will likely experience thunderstorms through Saturday night into Monday. With the highest probability for storms at 70%. here is their forecast for WalhallaReplyDelete
Saturday Night: Showers likely and possibly a thunderstorm before 1am, then showers and thunderstorms likely after 1am. Cloudy, with a low around 48. East northeast wind between 14 and 17 mph, with gusts as high as 23 mph. Chance of precipitation is 70%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Sunday: Showers and thunderstorms likely, mainly before 1pm. Cloudy, with a high near 60. Chance of precipitation is 70%. New rainfall amounts between a quarter and half of an inch possible.
Sunday Night: A 50 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 49.
Memorial Day: A chance of showers and thunderstorms. Mostly cloudy, with a high near 60.
My guess is that we will see some form of MCS move through our area along a possible front, either forming to the west of us or towards our east. Either way I can bet on some strong storms popping up in the RRV, as they are forecast along the and south of the border. They have also been maintaining the same outlook for 5 days now. Even Rob mentioned they are likely again this weekend in our area, they can even occur with cool temperatures as long as there is moisture.
Overall we will have to see how thing's turn out, and play it by day.
Judging by radar and surface temperatures, looks like rain is changing over to wet snow this evening over the Swan River/Ethelbert/Roblin areas. Wet snow reported in Yorkton right now.ReplyDelete
Starting to look like the frost risk for tomorrow night will be marginal over the RRV with slightly warmer 850mb temps forecast and a few more clouds. I think it's relatively safe to say the Winnipeg core will be frost-free, with an off chance of frost in areas closer to the Perimeter Hwy.ReplyDelete
Will be interesting to see if we get a real round of convection with the next system or just a massive rain shield. Extremely promising push of warm air associated with the next system that will develop a sharp warm front over North Dakota, but shear isn't super favorable for storms and there looks to be an extremely strong deformation zone with the upper low.
This disturbance has the hallmarks of another binary or split system. The key parameters to look for in terms of heavier precipitation are i) the nose of the LLJ/ instability gradient - which look to set up off to our SE, and ii) the deformation axis and trowal of the main parent low - which looks to set up mainly over SW Manitoba and Saskatchewan in an upslope trajectory. QPF is usually overestimated for our region in such cases.
The Grand Forks NWS jurisdiction does not include S Manitoba. Note there is no mention of frost potential in their discussion for Friday overnite into Saturday morning.. that's no guarantee it won't happen up here.
Actually the latest American guidance, as alluded to by Brad, shows a narrowing window of clear conditions overnite on Friday. GFS even shows some virga affecting areas along the int'l border. Given the strong SW jet aloft, it seems to make sense and hopefully the trend continues.
Meanwhile, it's warm and humid in Eastern Canada...ReplyDelete
Huntingdon, Quebec recorded a humidex of 37C, the highest this year in Canada.
About 2-5 cm of wet slushy snow reported over portions of western MB towards the SK border overnight into this morning. Wet snow reported in Dauphin, McCreary, Russell, Swan River, Rossburn, Binscarth as well as eastern SK through Yorkton, Melville and Regina. As for us, we'll see mainly cloudy skies and a little light rain or drizzle at times today, with highs struggling towards 10C. Hopefully clouds will stick around most of tonight to minimize frost threat for Winnipeg and RRV, but frost more likely to our north through Interlake and western MB where more clearing is expected tonight. Stay warm.ReplyDelete
Thank's for the info, I do follow The NWS forecasts south of the border because over past years any storms that were forecasted and formed ended up in our area of the province. Depending on the readily available atmospheric conditions for them to sustain themselves. Otherwise they would end up turning into showers. Although in this case we may end up missing out on them, we will have to see what Rob says...