Wednesday, September 17, 2008

Late summer weather before fall arrives Monday

Some nice weather is on tap for Southern MB over the next couple of days as Mother Nature gives us some late summer weather before the official start of fall on Monday. Thursday will see brisk southerly winds of 40 to 60 km/h developing in the Red River valley as a warm front moves through southern MB. Afternoon temperatures will climb into the 24-27C range along with plenty of sunshine. Friday will see a weak cool front push through from the Interlake, but temperatures should remain above normal Friday with highs of 25C or so before cooling off in the afternoon or evening as northerly winds develop. Saturday will likely see cooler temperatures as we get northeast outflow winds from a cool high pressure area over northern MB. Current advertised highs of 25C are likely over-optimistic for Saturday, with highs of 17-20c more likely in the cooler airmass. There could also be considerable cloudiness around along with areas of dense fog as that frontal boundary remains stalled over southern MB separating warm air to our south from cooler air to the north. (in fact, Saturday's weather may be much like today's.. overcast and cool) By Sunday we should be getting back into south or southeast winds which would boost temperatures back into the low to mid 20s (current advertised high of 27C still likely about 5c too high for Winnipeg and areas to the north and east) So although the bulk of the weekend is expected to remain dry, I don't think it's going to be as warm or as sunny as current forecasts indicate.

Fall officially arrives at 10:44 am Monday morning but current models are suggesting we'll be staying with above normal temperatures in the low to mid 20s through Tuesday before more fall-like temperatures return by mid to late week.


  1. Hey Rob, what happened with the forecast for last night and today? Before I went to bed, EC predicted a low of 5 with a risk of frost due to clear skies yet when I woke up the ground was wet, it was raining, and around 11C. Also today was supposed to be sunny. Just curious what changed overnight? Thanks,

  2. Chris..

    There was a weak impulse in the northwest flow that brought cloud in last night and those early morning showers (some elevated or mid-level instability). This impulse came in faster than expected overnight, and thus prevented the threat of frost that may have occurred had we stayed clear all night. I must admit, I was surprised by the early morning rain as well.

  3. Here is some encouraging weather data...

    The GFS is showing the chance of heavy snowfall around Saskatoon, SK on Sept. 25. The model is saying 20 to 30cm is possible, although with the warm ground conditions it may not stick very well.

    Even if the snow doesn't accumulate to those amounts, just think about having sub-zero weather and heavy snow just a week after being in the mid-twenties!

  4. Thanks! Yes I too was very surprised by the rain this morning. When I went to bed around 11pm, it was clear and cooling off (around 8C). I figured we were in for a cool one. By "impulse", what do you mean?

  5. Impulse usually refers to a smaller scale area of lift in the atmosphere..

  6. Interesting spread of forecast highs for Saturday for Winnipeg..

    Env Canada........ 25C
    Weather Network... 21C
    CTV Winnipeg...... 20C
    AccuWeather....... 20C
    CBC Winnipeg...... 17C
    Intellicast....... 15C

    A 10 degree difference of opinion between 6 sources. As you can see, EC's forecast of 25C is the warmest of all, and judging by the upcoming pattern for Saturday, that forecast high will likely drop.

  7. As expected, EC's forecast high for Saturday has dropped significantly.. from 25 yesterday to 18c today. This is more in line with other guidance for Saturday as a high pressure area over northern MB pushes cool air southward. This shows the benefit of shopping around for a second opinion on the weather forecast, instead of relying on just one source.

    The forecast is still calling for straight sunshine on Saturday but I suspect there will be a lot of low level cloud around which is typical with these cool outbreaks in the fall.. much like what we saw Wednesday.

    Likewise, Sunday's forecast high of 27C is likely too high as well as the GLB model is too aggressive pulling the warm air back in here. Look for highs in the low 20s Sunday before we get back into the mid 20s by Monday.

  8. Wow.. 29C! Quite the change from yesterday's 14C! But look at Saturday's forecast high now.. back to 14c! :( Ahh, the roller coaster weather of fall!

  9. The very cold air is not that far off to the north!
    You know Thompson and Churchill!
    They are struggling to get into the single digits during the day
    All it is gonna take is one major cold front and we could be getting a taste of some serious cool readings!

  10. Now you know why I come here and get the weather forcasts instead of EC and the Weather network! Your hit rate if far more accurate than any other. Heck, I'm just learing about the weather and my hit rate seems to be better that EC.

    Great site, informative and pretty accurate.


  11. Thanks for the comments Brendon. Glad you find the site useful.

    Unfortunately, modern day forecasts have been reduced to a single icon showing a number or two. This is far too simplistic to describe what's going on with the weather.. and this is what's missing with modern day forecasts... an explanation of what's going on, and how the forecasts may change. This blog gives me the forum to provide some insight into the forecast, and to give a lot more detail than a simple icon can.

    Note that John Sauder of CBC does the same thing on the CBC weather site, and I find his forecasts one of the more accurate ones for the Winnipeg area.

  12. Rob, I find your insight and explanations very helpful. You are very credible. Question for you: on an ongoing basis E.C's forecasts are out of whack.I follow the U.S. National Weather Service forecasts for Pembina North Dakota and, while it is 65 miles away and conditions can vary from Winnipeg,the Pembina forecast is pretty close to what Winnipeg should expect most days yet there is often a big difference between E.C and the N.W.S. It seems to me as a layman we in Canada are receiving an inferior weather forecasting product; whather that is due to technology, region size, budgets, whatever. Do you agree and what do you recommend we do about it to try to get it to change? It seems the public just shruga their shoulders and jokes off when the forecast is wrong

  13. Mark..

    Comparing EC and the NWS is kind of like comparing the CFL with the NFL.. 2 different leagues.

    EC has endured enormous budget cuts in the past 10-15 years.. so much so that it has been forced to centralize and automate a lot of its weather forecast program. This has been necessary so that EC can concentrate on "high-impact" weather within the first 24 hours as its primary focus. And to that end, EC is doing a better and better job when it comes to forecasting severe weather.

    But consider the difference in the area of coverage between EC's Winnipeg office, and NWS Grand Forks. EC-Winnipeg covers all of Manitoba, southern SK, and Nunavut including Baffin Island. NWS Grand Forks covers eastern ND, and northwest MN.. roughly the same size as southern MB. If NWS Grand Forks had the same area to cover as Winnipeg, they would be responsible for forecasts from Grand Forks to Miami! Due to their much smaller area of responsibility, NWS offices can focus their attention on a much smaller area, which can lead to more accurate day to day forecasts.

    As to what can be done about it.. well, you can always communicate any concerns you have about the weather service with your local MP or the minister of the Environment. In addition, if you have a specific complaint about a particular forecast, or an aspect of EC's weather program, you can submit your comments through the Weatheroffice website (click on the "Contact Us" link.) EC is obligated to address every comment it receives.

    Last but not least, try to obtain weather information from a variety of sources.. not just EC. Getting different opinions will give you a better idea on the general consensus of any given forecast.

  14. Well..speaking of forecast inaccuracy... overnite lows are going to dip colder than projected by EC. Very strong cold advection, very low upstream dewpoints and little in the way of upstream clouds all point to near freezing temps by dawn in rural areas outside Winnipeg.

    Already some 3's and 4's showing up outside the perimeter and if the winds back around to the NW from the current NE... the airport will quickly plunge towards zero.

    I must say I am surprised that EC did not put out a frost warning given the strength of the cold advection and an arctic high building down with very cold upstream dewpoints. I did not have a chance to look at any analysis/models until recently. Wow, always tough to get used to the cold.

  15. Widespread light frost outside Winnipeg on Saturday morning. Flow stayed NE all night which may have prevented YWG from dipping below freezing. Frost forecasts have been extremely wonky this season from EC... I don't remember them being this bad before.

  16. According to Channel 48
    we got down to 0.3 C ( at the airport)
    CLOSE enough
    I'm sure even parts of the city got Frost last night!

  17. No frost here in Charleswood (saved by north breeze off the city) but I see Sanford, Starbuck, Fannystelle areas likely had some light frost outside the city limits..

    By the way, frost warnings officially end tomorrow with the official start of fall. After that, if frost is expected, then frost is mentioned in the regular forecast until Thanksgiving, but no warning is issued.

  18. One thing I don't understand is why EC doesn't issue Frost Warnings later into the season...This year is a prime example of why they should. Soybean and Corn crops are still on the fields, and will be until at least late September. These farmers are closely watching the forecast, because frost right now would be disastrous. With the Frost Warning period ending in a couple days, frost forecasts likely will receive less attention.

    I think EC should continue to issue Frost Warnings until around October 1.

    With all this debate about forecasts, I thought I should give my say. First of all I want to mention that EC forecasts often are criticized, and rightfully so. Although other forecasting companies often aren't much better, they just aren't in the spotlight as much. Rob is right on his point about government cut-backs. EC meteorologists are one of the best teams of weather personnel in the world. They do an excellent job for what they are given to work with. Rob really put it into perspective when he compared PASPC Winnipeg's forecast region, compared with NWS Grand Fork's. Grand Forks probably has equal personnel, but only does a slightly better job. That really shows you what great work the men and women do here in Winnipeg. If the government gave the weather sector more money, rather than giving it to oil companies and other useless causes, we would easily be able to say that Canada has the best weather service in the world.

  19. Looks like there is a risk of a thunderstorm for tomorrow night!
    OH BOY!
    Could be the last one of the year!!

  20. Scott..

    The reason for ending frost warnings on the first day of fall is because that is around the average date for the first frost in much of southern MB. After Sept 21st, the occurrence of frost is not really an unusual occurrence, which is the justification for not issuing warnings. Frost however is still mentioned in the public forecast until Thanksgiving mainly for the home gardeners. You are correct to point out that every year is different with regard to growing seasons and crop development (as well as local climatology), but for simplicity, it is preferred to have the same deadline each year for everyone rather than a variable deadline based on each year's or each region's growing season.

    Again, if people do not agree with aspects of EC's weather forecast program, I would encourage them to send in their comments and feedback to EC through the Weatheroffice website under the "Contact Us" link.

  21. Looks like severe weather is likely tomorrow. The PASPC discussion is already buzzing with that idea.

    This looks to be one of the better threats of the year, with good shear, moisture, and instability. If we could get CAPE higher there would be the chance of widespread tornadoes. Currently I would expect maybe one or two, maximum, tornadoes to be reported.

  22. Yeah, looks like an interesting set up for the first day of fall! SPC showing a slight risk of severe tstorms over northern Plains for Monday. Afternoon destabilization will depend on how much sun can break through the clouds after the first wave of showers overnight into Monday morning.