Wednesday, 3 October 2012

Early Winter Wallop

Parts of southern Manitoba will be white like this soon
     Just under a week after we experienced near 30°C weather, winter is expected to make an incredibly-early return to southern Manitoba and northwestern Ontario Thursday into Friday. An intense low-pressure system is currently forming south of the border in South Dakota and will move into northwestern Ontario tomorrow. A tight pressure gradient with this system will pull in very cold air from the north into the system, allowing for heavy precipitation amounts, both in the form of rain and snow.

     For tonight, most of the precipitation will remain in the form of rain for southern Manitoba, especially the further north and closer to the lakes you are. The heaviest amounts are expected to be south and east of Winnipeg with up to 30 mm of rain possible. Further west and north, rainfall will be lighter and not-so widespread. However, areas downwind of the lakes will get some enhanced precipitation, giving some higher amounts in those areas. Winnipeg is expected to get some lake-effect showers tonight as north/northeast winds blow off Lake Winnipeg.

     Tomorrow is uncertain still at this point, but tomorrow is also when things get very intriguing. Heavy precipitation is expected to move in again from the south and wrap around in southeastern Manitoba into Thursday night and to start Friday. Much of this is expected to be in the form of snow with upwards of 30 cm possible to the east of Winnipeg, especially in the Sprague area. In Winnipeg, at the moment it is expected that we will be on the western fringe of this band of snow, therefore we are expecting to receive lighter amounts. However, lake-enhanced precipitation may be an issue. Elevation-enhanced precip will also be possible along the Manitoba escarpment.

     However, uncertainty is strong at this point as some models (NAM/GFS) are still bringing over 20 cm for the city, while GEM is only giving about 5 cm. Keep up to date on this situation on Rob's Blog as I wont have much time to update over the next couple days.


  1. Unfortunately it is still uncertain even as the event is happening now! Models are still debating when the rain will change over to snow. GEM keeps it until tonight, while nam/gfs change it over this morning. GEM gives about 2-5 cm, while the other two bring ~ 30 cm.... A wait and see game unfortunately.

  2. Snowed all day in southeastern Manitoba, including Winnipeg. Snow has been heavy and accumulating rapidly south and east of the city with over 10 cm. Amounts are likely higher than that locally. Winnipeg has been lucky as the vast majority of the snow melted on contact, despite snowing all day. About 2 cm accumulated in the city, locally higher, locally lower.
    Snow is expected to continue all night into tomorrow morning for much of south-central, southeast, east Manitoba. Winnipeg could see up to 5 cm depending how far east the main bands push. Another 10-20 cm is possible to the east, closer to the Ontario border.
    In addition to all this snow, about 20-40 mm of rain fell in areas south and east of the city yesterday and early today before it changed to snow.
    We really needed this moisture!

  3. Forgot to mention that areas downwind of the lakes will see enhanced snowfall tonight with higher accumulations. The same goes for the higher elevations of Riding Mountain due to upsloping.