Author: Brad

Brad lives in Winnipeg with his wife and two children and is the founder of A Weather Moment. He has loved weather from a very young age and has followed that passion through his life so far. He received a B.Sc. in Earth Sciences with Specialization in Atmospheric Sciences and is currently employed in the field of meteorology. You can find the author as WeatherInThePeg on Mastodon.

September Marks a Return to Seasonal Weather

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September closed out with a few beautiful days, bringing a month that had a bit of a cool start back to seasonal conditions. As for whether Winnipeg continued it’s 14-month above normal streak, that depends on which average you use. If you’re partial to the 1971-2000 means, then yes, we’ve extended the streak to 15 months. If you use the 1981-2010 means (which are the ones we use here at AWM), then unfortunately, our streak has come to an end.

September 2012 Summary

2012 Departure from Normal Temperature, with Year-to-Date mean

2012 departure from normal (or monthly anomaly of) temperature. The year-to-date mean is also plotted.

September 2012 closed out with an average temperature of 12.6°C, 0.28°C below the the 1981-2010 normal of 12.9°C. At -0.28°C below normal, the month of September ended Winnipeg’s above-normal streak at 14 consecutive months1. The warmest day in September 2012 came near the end of the month on the 29th when the mercury climbed to 29.6°C, a mere 0.4°C off the record for that day of 30°C set in 1905. No new daily high record temperatures were set this September. The coldest night was the night of September 22/23 when the mercury dropped to -7.1°C. This broke the previous record low for that night of -6.1°C set in 1879 and was 1.2°C off the record coldest night in September of -8.3°C, set on September 29, 1899. In total, just the one record low temperature was set this September.

2012 Departure from Normal Precipitation, with Year-to-Date total

2012 departure from normal (or monthly anomaly of) precipitation. The year-to-date total is also plotted.

September continued the significant precipitation deficit when compared to the normal. Usually we see about 48mm2 in September, but this year we saw a mere 4mm of precipitation. Receiving less than 10% of our normal rainfall for the month continues the precipitation deficit to 4 consecutive months in Winnipeg.

In other miscellaneous September statistics:

  • We finished the month with 0 days above 30°C, but 7 days at or above 25°C.
  • September 2012 did not break the top 50 warmest Septembers on record.
  • Despite our practically non-existent precipitation for the month, we still nearly quadrupled the record driest September of 1948, where only 1.3mm fell.
  • Our 4mm precipitation total for the month was only 2.5% of the precipitation that fell in the record wettest September of 1872, when 156.2mm fell.

2012 So Far

Year-to-Date Temperature Anomalies for Winnipeg, MB

Year-to-date temperature anomaly, by month, for 2012 (red) compared to the other 139 years on record for Winnipeg, MB, with the five warmest years (orange) and five coldest years (blue) noted.

As mentioned before, September’s deviation of -0.28°C from normal has brought an end to the above-normal conditions of 2012. Until September, every single month this year had been above-normal. Looking again at our Winnipeg temperature anomaly climatology, we can see that despite our slightly below-normal September average, we’ve managed to still remain the most above normal (by a hair) that we’ve ever been. Things still look to be on track for us to end up in the top 5 warmest years ever and we’ll keep updating each month to see where we end up.

Rest of 2012

As mentioned last month, sea ice in the Arctic is at a record low, which while it hasn’t prevented us from getting the odd cold outbreak, still looks to have the potential to reduce the strength/onset of the Hudson Bay arctic vortex that sets up and maintains a cool, northwest flow over the Eastern Prairies. While a month ago it also looked like El Niño was going to help us possibly see a warmer-than normal winter, over the past couple weeks the El Niño signal in the Eastern Pacific has significantly weakened. This means that any large-scale hints towards what sort of winter we’ll see are becoming rather muddled and no strong signal currently exists.

  1. Based on 1981-2010 normals. Winnipeg sits at 15 months above normal if using the 1971-2000 normals. ↩
  2. The normal precipitation for September is 47.6mm. ↩

Slowly Improving Weather in Store

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The weather will slowly improve over the next couple days as some warm air begins to slowly push across the Prairies.

3hr. Cumulative Precipitation for late this afternoon

3hr. cumulative precipitation from the RDPS for late this afternoon.

Today will remain mostly cloudy across Southern Manitoba with two main features to pay attention to. The first feature is a low pressure system that will slide from Southern Saskatchewan into North Dakota, bringing with it a chance of showers through southwest Manitoba through the morning and into the early afternoon. The second feature will be a trough slumping southwards through the Interlake into the Whiteshell. The southern extent of this trough will move through the Red River Valley in the late afternoon and evening, and as it enters the area, a few scattered convective showers or flurries will develop along it and move through the region. Whether we see rain or snow will depend on the exact timing of the system and what the temperature is; either way, accumulations will fairly insignificant and the showers likely won’t be widespread. Daytime highs will be around 6°C this afternoon.

After these systems pass, we’ll see skies slowly clear out overnight as temperatures drop to around the -3°C mark. A ridge of high pressure begins working it’s way into Manitoba; skies will remain mainly sunny as temperatures slowly climb. Tomorrow we should see daytime highs around 9°C through the Red River Valley, and increasing up to around 11°C for Friday. We’ll see a mix of sun and clouds on Friday as a weak system brings some cloud through the Red River Valley as it passes through central Manitoba.

The weekend looks relatively average, with no indications so far that any significant precipitation events are in store for us over the next week.

Gloomy Thanksgiving Monday

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This Thanksgiving will be nothing like last year’s (which featured temperatures in the twenties), as rain and wet snow make for a rather miserable holiday Monday.

Total precipitation accumulation for Monday's system

The GEM model shows generally 10-20mm of precipitation over Southern Manitoba

A low pressure system sliding south-eastward through Manitoba on Monday will be responsible for the precipitation, with rain beginning to move into Southern Manitoba early Monday morning. Temperatures on Monday will be cool, but generally not cold enough for snow with values hovering in the mid single digits during the daytime. By evening there will be a changeover to snow in some areas, mainly portions of Western Manitoba, as colder air is pulled down from the north. Areas in the Red River Valley can expect a bit of wet snow late Monday evening into the overnight period, but with surface temperatures remaining above zero, no notable accumulation is expected. Total precipitation accumulations will generally range from 10 to 20mm across Southern Manitoba by early Tuesday.

Unfortunately, conditions will improve little for Tuesday. It will be a chilly start to the work-week as cold air pulled down by the previous day’s low pressure system will not allow temperatures to climb much higher than the mid single digits at best. Monday’s low pressure system will have departed by Tuesday morning, so no more significant precipitation is expected (save for perhaps a few scattered showers or flurries). At this point models keep us in the single digits for Wednesday as well, so even normal weather will continue to elude us.

The late week period looks to remain fairly miserable, with temperatures staying stuck in the single digits. No more significant precipitation is expected later this week.

Improving Weather, But Remaining Cool

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The effects from the low pressure system responsible for yesterday’s dump of snow over southeastern Manitoba will linger for one more day before moving off and returning us to sunnier skies.

Snow piles up on the Trans-Canada Highway

Snow resulted in the Trans-Canada highway being reduced to one lane each direction as numerous cars hit the ditch due to icy road conditions.

We’ll see widespread flurries over the Red River Valley today, however the potential exists for significant accumulation in the lee of Lake Manitoba and Lake Winnipeg. Brisk northerly winds, combined with strong instability over the still-warm lakes, will advect fairly strong lake-effect snow bands southwards off the lakes. These will be long, narrow features that will depend significantly on the wind direction. Currently, it appears that the heaviest flurry activity will be along a N-S line near Portage la Prairie, and another N-S line just east of Winnipeg. Should the winds back to a little more NE than northerly, Winnipeg could certainly see some of the action. Most locations that see just general flurry activity will likely receive 2-4cm of snow; how much actually stays on the ground will be highly dependent on what the pre-existing ground cover is like. Areas that have mostly bare ground right now should have enough heat coming off it to melt most of the new snow that falls. Areas in the eastern half of the Red River Valley, which already have had 10-20cm of snow fall, will definitely see the snow slowly pile up on top of the existing stuff. For those that get caught for any significant period of time under the lake-effect bands of snow, 5-10cm is certainly possible, if not even a bit more than that.

Winds will remain fairly strong today out of the north at around 40km/h with gusts to about 60km/h. Temperatures will struggle through the day, with plenty of cloud and cold advection occurring; we’ll probably only see 2°C or so..perhaps up to 3°C.

Things begin to improve tonight; winds will die down this evening and the cloud cover will start to clear as a ridge pushes into southern Manitoba from the northwest. Temperatures will hover around 0°C until the clouds break up, then temperatures will drop to about -5°C for the remainder of the night.

For Saturday, we’ll see sunny skies over southern Manitoba as we sit under the influence of an arctic ridge. Temperatures will only climb to about 7°C, so it will remain fairly chilly despite the sunshine.

On Sunday we’ll see increasing cloud throughout the day and a high of about 8°C. The cloud is coming ahead of a low pressure system dropping southwards from the Arctic along a reinforcing blast of cooler air. Showers will push into portions of the northern Red River Valley overnight, with the more organized precipitation looking to fall over the northern and eastern Red River Valley into the Whiteshell on Monday. Currently, it looks as though this precipitation will fall as rain.