Pattern Change On The Way

     Just two more chilly days to get through and then things will get better! Still breezy out of the northwest today under cloudy skies and highs in the high single digits, a monotonous weather pattern which has been with us since late last week. At least tomorrow, the sun should be with us, but it will still be chilly with highs around 10°C.

Long weekend forecast:

     The weather pattern changes tomorrow night as a strong southerly flow sets up over southern Manitoba. It will be very windy in the afternoon on Saturday with southerly winds up to 40 km/h and gusts up to 60 km/h. Should see highs in the mid teens, closer to normal for this time of year. Mid teens are expected to continue Sunday and Monday. There will be a slight chance of showers on Sunday, but I'm not expecting much rain overall this weekend. Winds will be calmer Sunday and Monday as well, so overall, looks like a pleasant long weekend ahead!

     Right now, there are no signs of prolonged cool downs through to the end of October. In fact, long range guidance suggests a warmer than normal second half of October overall. The following map is just one forecast for temperature anomalies for the October 17 to 24 period. Have not seen this much agreement on above normal temperatures in a long time!

Temperature anomaly forecast for the October 17 to 24 period. NAEFS model.

Growing Season Ends, Cold & Blustery Weather Continues

     The growing season officially came to an end in most of Winnipeg today with frost as temperatures dipped below zero. The airport dropped to -2.2°C, while temperatures dipped to -1.5°C at my place in south St Vital. Only the downtown area managed to escape frost, with a low of 1.1°C at The Forks and 1.0°C at the University of Winnipeg station.

     This first frost however, is later than normal. 1981-2010 normal first frost at the airport is September 24. The temperature actually dipped below zero already yesterday evening, making it the latest first frost of the season since 2005 when we didn't get our first frost until October 6. In case your wondering, this only ties as 12th latest first frost since 1872.

     Many parts of the city also saw their first snowflakes of the season yesterday afternoon as lake-effect precipitation moved in. The airport did not record any snow however.

     The cold and windy conditions will continue until at least Wednesday. Showers and flurries will be possible each day, but significant accumulations are not expected.

     I do have some good news. There are hints of warming up for the Thanksgiving weekend. That may come with some more chances for some rain however.

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.