Wednesday, 1 October 2014

Another Warm September Overall

     Despite some significant cool downs mid month and again in the last few days of the month, September still managed to finish above normal. Although only 0.6°C above normal, it was the most above normal month since September last year.

     This September continues the trend of warm Septembers in the Winnipeg area. This was the 16th warmer than normal September in the last 21 Septembers (since 1994). It's been 15 years since we've had a September that was at least 1.0°C below normal (last time was 1999). In that same period, 8 finished over 1.0°C ABOVE normal.

The warmth coincided with the leaf colour change
     The month finished above normal mainly due to an historical warm spell late in the month. Temperatures were generally 10-15°C above normal from September 22 to 27. Daytime highs exceeded 25°C on 5 of those 6 days. The hottest day was the 26th when highs reached 30.2°C, just shy of the old record of 31.7°C in 1952 for the day. The humidity during the week was the main story for the Red River Valley. 6 high dewpoint records were broken in Winnipeg along with the latest occurrence of humidex over 35 on record since 1953. Humidex values reached 35.8 on the 26th.

     Thunderstorms were also a big story in September, especially early in the month. Only 4 thunderstorm days occurred at the airport, just above the normal of 3 days. However, more occurred in the south end where the bulk of the activity occurred. 6 thunderstorm days occurred here in South St Vital. Blinding downpours, crashing thunder and strong winds were the main stories with most of the storms. The late season burst in activity salvaged the generally quiet season we had in the summer.

     So far, the airport has seen 23 thunderstorm days this year, the most since 2010. Tragically, this is on track to being yet another below normal year for t-storm activity as a result. The last time we had an above normal thunderstorm season was in 2007. Note there were more t-storm days in the southern part of the city this year with 25 days at my place so far. Thunderstorms can still occur in October, so these stats could still go up a bit if we're lucky. The 1981-2010 normal number of t-storm days in a year is about 26-27 days.


  1. Didn't get a whole lot of rain last night. Bulk fell in the evening with generally 1-4 mm in the city. Brought my rainfall total to 46.0 mm for September, a bit higher than the airport. We wont warm much today with highs around 16-17°C or so. Winds will be not as strong this afternoon, but still breezy.

    Fairly sunny to start the day tomorrow. Increasing cloud in the afternoon with a good chance for rain in the late afternoon and evening. Can't rule out a rumble of thunder, but I don't think we're talking about widespread storm activity here.

    MUCH colder on Friday. It'll feel more like November! Very strong winds in the morning from the north-northwest at 40-50 km/h and gusts up to 70 km/h possible. Periods of rain as well in the AM hours. In total, could see 5-10 mm late tomorrow through to Friday. We'll likely only see temperatures hovering in the mid single digits in the afternoon on Friday.

    Frost will be possible on Saturday morning as skies clear in southern Manitoba. However, I am curious to see if we manage to remain under some lake effect cloud and drizzle under the continuing northwest winds. If we did manage to stay under the cloud, we may escape frost in Winnipeg... Nonetheless, to be safe, be prepared for frost because if we do clear, can't rule out lows in the -2 to 0°C range. Another cold one in the afternoon with a high in the mid to high single digits. Some more showers may be possible late in the day.

  2. JJ, Tell me the GFS is wrong.... They indicate 10 cm of SNOW next sunday-monday.


  3. Colorado Low moving into Ontario basically retrogades westward early next week. Clearly, GFS is most aggressive at this point with its 9 mm of rain and 10 cm of snowfall. GEM keeps it all to our northeast. ECMWF is further west as well, bringing some light snow into our area, but with little accumulation.

    So all in all, it does look like some snow will be possible early next week. Too early to say if we'll see any accumulation but that 10 cm is certainly on the high side. It will depend somewhat on if the snow would fall at night or at day. If it falls during the day, I'd say 10 cm wouldn't be very likely.

  4. Pleasant start to today with sunshine. Should reach 15-17°C today before cloud takes over this afternoon. Showers likely late afternoon and evening, and there could even be some weak thunderstorm activity.

    Reality check tomorrow with very strong north-northwest winds of 40 to 50 km/h and gusts of 60-80 km/h. Certainly not good news for the lakes. Rain will be likely as well overnight through to the afternoon with 5-15 mm likely. Might clear out in the evening, but again, it's hard to say right now if we'll see lake effect cloud or not tomorrow night. Makes low forecasts tricky. If we clear out we could see lows around -2 to 0°C with frost, but if the wind and lakes work in our favour we may see lows stay just above zero and escape frost. Nonetheless, cold weekend ahead with highs in the high single digits both Saturday and Sunday. Frost will be possible again Sunday morning.

  5. Turning into a tough call for tomorrow. There is the potential for our first snowflakes of the season. I'm personally leaning towards primarily a rain event as it may be too warm, but can't rule out some snowflakes embedded at times. As long as precipitation rates don't get too high, I don't think we'll see much, if any, accumulation if snow does fall tomorrow.

  6. Special Weather Statement issued for Winnipeg, the RRV and Southeast MB. That's either to address the thunderstorms for this evening or possible snow and wind for tomorrow. Not sure because there a no details listed under the statement at this time.

  7. Precipitation enhanced just west of Winnipeg this morning from lake-effect off Lake Manitoba. Some reports of snowflakes around Elie with that. Generally, the bulk of the rain remained to our north and east overnight so we really didn't get much rain at all in Winnipeg with just about 1-2 mm so far. Light showers to continue through the day, which could mix in with some snowflakes late in the day.

    Tough call for tonight when it comes to clearing and frost potential. It appears the bulk of the lake effect should remain just to the west of the city, but it will be close. Could drop below zero here if we get enough clearing. However, with strong winds continuing, that could also reduce the risk of frost. Overall, I'd say better chance for frost Sunday morning.

    System in Ontario retrogrades this weekend and could bring some more showers or even flurries late Sunday into Monday. Too early to say how much we'll get, but it doesn't look significant.

    Unfortunately, looks like we've really entered back into the below normal regime, with little to no signs of getting more prolonged above normal conditions for the next couple weeks.

  8. Heavy wet snow in the Falcon & West Hawk lakes area!

  9. We just narrowly escaped our first freeze of the season in Winnipeg this morning thanks to cloud cover. Low of 0.2°C at the airport overnight occurred during a brief period of clearing. Not the same story everywhere in southern Manitoba unfortunately. Lots of sub-freezing lows in southwestern Manitoba with areas along the US border being the coldest. Deloraine down to -6°C and Pierson down to -5°C. Also some freezes southwest and south of Winnipeg, but more patchy in nature.

    Anyway, we should stay quite cloudy throughout the day today and there could be some showers, but not much expected. Should reach 7-8°C.

    Again, difficult forecast for tonight when it comes to clearing. If we clear, we could see lows in the -2°C to 0°C range. Otherwise, we may escape another freeze if we stay fairly cloudy again.

    A freeze is possible again Monday morning, however, I think the chance will be lower as we should see a lot of cloud. Periods of rain likely in the afternoon with a few mm possible.

    Still don't see much light at the end of the tunnel when it comes to this below normal regime. At least it isn't terribly cold though.

  10. Low -0.1°C as of 9 pm this evening... Officially the first freeze of the year. Puts this year's growing season as 139 days long at the airport from May 18 to October 3, the longest since 2005.