Mild Weekend Ahead

The first weekend in October is looking like a great one; plenty of sunshine will be seen over the coming few days alongside temperatures 2–3°C above normal for this time of year.

17°C / 3°C
16°C / 3°C
Mainly sunny
16°C / 8°C
Mainly cloudy; chance of late-day showers

Today and tomorrow’s weather pattern will be dominated by a large ridge of high pressure anchored from northwestern Ontario into northern Quebec, whose presence will be one of the guiding impacts on the track of Hurricane Joquain. Here in Manitoba, dry outflow from the ridge will ensure skies stay clear and a polar jet stream mainly locked in the Arctic will keep the cooler weather well to our north and allow for slightly above-seasonal daytime highs[1] through the weekend.

Here in Winnipeg, we can expect mainly sunny conditions today and tomorrow with daytime highs around 16–17°C. Winds will be out of the south or southeast at 20–30km/h both days, although today will likely be a bit windier than Saturday. Overnight lows both tonight & Saturday night will sit around +3°C.

Sunday will see the pattern begin to break down a bit. The quasi-stationary ridge to our east will begin to shift off towards the east, easing the pressure gradient over the Red River Valley and finally giving us a break from the windy conditions that will have been in place for several days by that point. As things shift to east, however, cloud will begin to spill eastwards into the valley from a low pressure system that has been stalled over the western high plains for several days. This means that Winnipeg will likely see a fairly cloudy day, but daytime highs should be relatively unaffected and remain a couple degrees above normal near 15–16°C.

As we head into Sunday night, the chance for some light shower activity will increase. Very little is expected by way of significant precipitation, although at this point it appears that the slightly unsettled conditions will likely persist through Monday & Tuesday next week.

Above-Normal Temperatures To Persist

Looking ahead into the long range, it appears that the above-normal temperatures are likely to stick around.

NAEFS 8-14 Day Temperature Anomaly Forecast
NAEFS 8-14 Day Temperature Anomaly Forecast valid for October 10 – 17, 2015

As the NAEFS 8–14 day outlook here shows, there’s a high probability of above normal temperatures throughout most of Manitoba for the period of October 10–17th, as well as for almost the entirety of the remainder of North America. The NAEFS ensemble has been persistent with this trend for quite a while now, and is what we expect to see in strong El Niño years as it often shunts the polar jet stream to the north and east, allowing warmer air to spill eastwards through the southern Prairies in a more zonal upper-level flow.

El Niño Winter Pattern
A typical generalized winter weather pattern during strong El Niño events. Credit: NOAA Climate

In El Niño years, persistent low pressure off the west coast of North America tend to produce ridging over the Rockies, drawing warmer air further to the northeast. This ridging shunts the polar jet stream further to the northeast and typically keeps the Arctic blast freezer bottled up a little more.

How strong is this El Nino now? The only real way to answer this is to throw a bunch of numbers at you. Essentially, it’s “pretty strong.”

This year’s El Niño is on track to be one of the strongest on record, which would have a high correlation of generally persistent above-normal temperatures. This doesn’t mean that cold weather isn’t possible this winter; rather it just means that any cold outbreaks will likely be shorter-lived than typical. One of the potential down-sides to this year’s event is that strong El Niño events tend to correlate with cloudier winters in the Red River Valley.

Again, all this is very generalized climate speak; the day-to-day weather can certainly vary significantly and the end result won’t just be a result of the El Niño, but also its interactions with the AO, NAO, and a few other large-scale patterns.

At the most simple level, though, it’s looking like above-normal temperatures will continue for a while yet. Perhaps the most disappointing thing at this point will be watching that “seasonal high” curve get lower and lower.

Enjoy the pleasant fall weekend!

  1. Seasonal daytime highs for this time of year in Winnipeg are around 14°C.  ↩

Seasonal & Unsettled Weather Ahead

The cold weather evidenced by a temperature that dipped down to a very chilly –3.8°C at the Winnipeg Airport on Tuesday morning has quickly been replaced by more seasonal conditions which will persist through the remainder of the week. Sunshine will be a bit harder to find, though, with plenty of cloud and unsettled weather in place as low pressure system stalls out over Southern Manitoba.

17°C / 11°C
Increasing cloud; showers developing this afternoon
15°C / 7°C
Cloudy with showers tapering off
17°C / 5°C
Partly cloudy

Today will start off fairly pleasant with temperatures in the 8–10°C range and partly cloudy skies. The cloud will only increase as the day progresses, however, ahead of an approaching low pressure system. As the low gets closer, winds will strengthen out of the south to 30–40km/h, with some gustiness on top of that, while the temperature climbs towards our daytime high of 17°C.

Scattered showers will develop through the afternoon and become more widespread heading into the evening. There’s a very outside chance of a thunderstorm, but the risk is quite isolated and something along the lines of isolated moderate to heavy showers activity is more likely. Rainfall amounts overnight will vary widely with anywhere from 2–10mm generally expected, however localized patches of more or less are possible. Winds will continue out of the south to southeast at 30–40km/h overnight with a low near 11°C.

GDPS 12hr. QPF valid 00Z Friday October 02, 2015
One shot in the dark at rainfall totals across Southern Manitoba through the day on Thursday.

Thursday will see the showers gradually taper off through the day as temperatures climb to around 15°C with breezy south-easterlies continuing at 30–40km/h. Skies will remain fairly cloudy through the day and into the overnight hours. Some clearing will work its way into the Red River Valley from the east overnight as temperatures dip to around 7°C.

Friday will finally bring clearing skies and slightly warmer temperatures as the cloud pushes off to our west. Winds will remain fairly breezy at 30–40km/h for much of the day before tapering off towards evening hours. Temperatures will climb into the upper teens for daytime highs through the Red River Valley and dip down to a chilly 5°C or on Friday night.

Pleasant Weekend Ahead

All things considered, this weekend will be quite pleasant. Just a few clouds are expected to be around with daytime highs in the mid-teens & less windy conditions than we’ll have rounding out the work week.

First Risk of Frost This Year

Most of southern Manitoba will be at risk tonight as the potential for the first frost of the fall looms.

There will be a risk of frost in southern Manitoba on Tuesday morning
There will be a risk of frost in southern Manitoba on Tuesday morning
13°C / 0°C
Mainly sunny
15°C / 10°C
Mainly sunny
17°C / 9°C
Mix of sun and cloud


Today will feature mainly sunny, but cool conditions. A surface ridge of high pressure will bring about chillier weather in southern Manitoba, with daytime highs only in the low teens. The wind won’t make it feel any warmer, with speeds of 30km/h out of the north-west.

Skies will remain mainly clear overnight into Tuesday, allowing temperatures to drop near the freezing mark. Low-lying areas are very likely to receive frost on Monday night. Elsewhere, frost will be more spotty, but the outer edges of Winnipeg will be at risk, with the downtown area likely staying above freezing.


After we warm up from near freezing temperatures on Tuesday morning, the rest of the day will be rather pleasant. Temperatures will climb into the mid teens under mainly sunny skies and light winds. Overall, it will be a fairly typical late September day.


Wednesday looks to be the warmest day in the first part of the week, with temperatures in the mid to upper teens. The wind will be gusty from the south or south-east though, making it less pleasant than it would otherwise be. Skies will range from a mixture of sun and cloud to mainly cloudy.

Above Average Western Pacific Typhoon Season Continues to Produce

Typhoon Dujuan formed earlier this week on Wednesday in the middle of the Pacific Ocean and continues to barrel westward toward northern Taiwan and the eastern shores of China.

The Western Pacific typhoon season, which is running above average this year with already 21 named storms, has primarily affected Japan, China, and the Philippines. The average number of named storms for a full season averages around 25 storms (May until late October is peak Western Pacific storm season, but storms can form outside this period). Dujuan currently sits about 1200km east of Taiwan shores and is still undergoing intensification. As of Friday night the storm had sustained winds of 167km/h, gusting up to 200km/h and had an estimated central pressure of 960mb. The Japan Meteorological Agency forecasts that by the end of the weekend it will have intensified to a high end category four equivalent storm as it approaches Taiwan. With sea surface temperatures in the order of 30°C and shear values between 5-10kt their forecasts for a powerful typhoon is warranted.

Infrared satellite imagery of Dujuan on Friday night shows very cold tops on the south side of the eyewall and an eye that has cleared out nicely. (Source: UW-CIMSS)
Infrared satellite imagery of Dujuan on Friday night shows very cold tops on the south side of the eyewall and an eye that has cleared out nicely. (Source: UW-CIMSS)

Latest 00z forecast models on Friday night had the storm brushing northern Taiwan and then pushing onto China’s mainland by Monday night near the city of Wenzhou. With a track like this, northern Taiwan would take the brunt of the storm with severe storm surge, high winds and heavy rain, while the threat to China wouldn’t beas major they would still see extremely heavy rainfall with the remnants. However, it must be noted that there is much uncertainty about the specific track still and the storm could deviate from current model forecasts.

Only one of the numerous forecast models' output for Dujuan. This one from the 25/12z ECMWF - brings the storm down to 935mb near northern Taiwan. (Source: Wunderground)
Only one of the numerous forecast models’ output for Dujuan. This one from the 25/12z ECMWF – brings the storm down to 935mb near northern Taiwan. (Source: Wunderground)