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.

Sunday, 28 September 2014

Summer Dream Ends; Fall Back as Scheduled

It was a wonderful week to take in the fall colours
     What a week last week turned out to be across Saskatchewan and Manitoba! Numerous records were shattered. Here in Winnipeg, the records broken were mostly related to the unseasonably high humidity. In fact, a total of 6 dewpoint records were broken:

Table: Daily dewpoint records broken during our ''heat wave'' last week in Winnipeg (records since 1953)

Date & type of record
NEW record
OLD record
Sept 24 – high minimum
9.1°C in 1992
Sept 25 – high maximum
16.8°C in 2008
Sept 25 - high minimum
11.0°C in 2009
Sept 26 - high maximum
16.6°C in 2008
Sept 26 - high minimum
12.2°C in 1986
Sept 27 - high maximum
13.9°C in 2010

     The dewpoint of 18.1°C on September 26 was the 4th highest on record for so late in the year. It was also very close to being the highest for so late in the year: a dewpoint of 18.6°C on October 8, 1997.

     Only one temperature record was broken however, perhaps because temperature records go back much further, all the way back to 1872. Nonetheless, a minimum temperature of 17.4°C on Friday the 26th shattered the old record high minimum of 14.4°C in 1950. This was also the highest daily minimum temperature for so late in the year.

     The heat and humidity on Friday also broke yet another record. A maximum humidex of 35.8 was the highest for so late in the year and the latest occurrence of humidex over 35 on record. A high of 30.2°C was just shy of the old record high of 31.7°C in 1952 and brings our total of 30°C days this year to 8 days. This is below the 1981-2010 normal of 14 days for an entire year.

     It was even hotter out west, where this burst of late September heat was basically unprecedented for so late in the year. In Brandon, temperatures exceeded 32°C for two consecutive days on Thursday and Friday. Highs of 34.0°C and 32.8°C, respectively, did not only shatter the old record highs, but were also the hottest temperatures ever recorded for so late in the year since 1890. Previously, the latest Brandon ever got that hot was on September 22, 1897 and 1938 with highs of 33.9°C. Humidex values reaching 37 were also unprecedented for so late in the year.

     The hottest temperatures recorded last week were 35.1°C in Wawanesa on Thursday and 35.1°C in Swan River on Friday.

     Fall-like conditions return today with temperatures remaining steady near 10°C. Periods of rain will continue until this afternoon. 5-10 mm is likely with locally higher amounts possible. Low cloud will likely remain tomorrow, keeping our highs in the low teens. Warmer for Tuesday and Wednesday with highs in the mid to high teens. A system will likely bring some showers Tuesday night into early Wednesday however. We cool down for late week. There is the potential for our first frost Saturday morning, but it's too early to confirm. Just keep in mind the possibility exists.

Tuesday, 23 September 2014

Near Record-Breaking Heat On The Way

Beautiful fall colours and cloudless sky on Monday evening
     If you thought it was warm yesterday, that 26.5°C high was only the beginning of what could possibly be a record-breaking end to the week.

     To start, today will be very similar to yesterday. Nothing but sun and a high around 26-27°C again. It will be windy from the south at 25 to 35 km/h or so. Clouds will increase tonight, giving way to a cloudier start to the day tomorrow. The clouds -should- clear out by the afternoon, giving way to highs around 22-25°C, depending on how early the cloud clears.

     Mother Nature really cranks up the heat on Thursday and Friday as very warm air moves in from the southwest. Highs in the low 30's look likely, with highs around 30-33°C on both days. This will come close to or break some record highs. The old record for Thursday is 31.1°C in 1950 and on Friday, 31.7°C in 1952. We'll stay quite mild at night as well, with lows in the mid to high teens, potentially breaking some high minimum records.

     The humidity will also be on the increase, making it feel a little uncomfortable for some. With dewpoints reaching the high teens, humidex values will push at least the mid 30's. We may come close to reaching the highest dewpoint values for so late in the season. We'll have to exceed October 8, 1997's dewpoint value of 18.6°C to break that record.

     Looks like we'll cool down a bit on the weekend, but models are not agreeing on how severe and prolonged the cool down next week will be. Will keep you all up to date on the records and possible cool down in the days to come.

Saturday, 20 September 2014

Rain & Storms Today Then Warming Up

You can access this webcam by CBC at any time here
     In case you slept in this morning, thick radiation fog blanketed the city early this morning. The CBC webcam just southwest of downtown (seen to the right) looked pretty cool this morning as it was above the fog. Winnipeg's skyscrapers were poking out above the fog.

     Another thing I want to mention was the supercell storm just south of the border last night. The storm dumped what appears to be baseball sized hail just south of Emerson as seen in this photo. The storm then dropped a tornado into Minnesota, just south of the Canadian border. This video possibly shows this tornado.

     For today, showers with embedded thunderstorms are expected to begin sometime after 10:30 am in Winnipeg and end in the afternoon. Showers may be heavy at times, especially in storms. Even after the main band passes through, the chance for showers and pop-up storms remain for the remainder of the day. A good 5-10 mm, more in storms, could fall today.

     A fairly cloudy start to tomorrow with possibly some patchy fog. Clearer skies for the afternoon and we should reach around 17°C or so, seasonal for this time of year.

     The warmup begins on Monday with nothing but sun and highs around 23°C or so. Similar on Tuesday with highs around 24-25°C. The warm conditions are expected to continue throughout the entire week and possibly even into next weekend. This will make for a fantastic end  to September and will coincide with the leaf-colour change to create some wonderful fall-photo opportunities. This will also be good news for farmers who need warm and dry weather. For the Winnipeg area, this will extend the growing season later than normal. The 1981-2010 normal first frost at the airport is September 24, but we'll be pushing it much later this year. We likely wont get our first frost until October this year.