Manitoba lakes freezing up quickly

MODIS satellite image of MB lakes
Saturday Nov 8 2014

MODIS satellite image of MB lakes
Thursday Nov 13 2014

Well below freezing temperatures over the past week has brought the first snows of the season over much of southern MB as well as a rapid freeze up of the Manitoba lakes. The two "false colour" MODIS satellite images above were taken just five days apart between Nov 8th (left) and Nov 13th (right)  The images show a much different landscape over southern MB over that time with more extensive snow cover (shown in light blue) and a rapid freeze up of the western MB lakes, with Lake Manitoba and Lake Winnipegosis now mainly ice covered. Lake Winnipeg still remains generally ice free except along the shores and some bays.. which is allowing lake effect cloud and flurries to persist as cold winds blow over the open water (open water seen as dark blue on satellite imagery with clouds seen in white)  In fact, you can see the bands of heavier lake effect snow over the past day or two immediately south of Lake Winnipeg and Lake Manitoba, with less snow cover elsewhere over southern MB (bare land shows up as light brown) 

With a continuation of well below freezing weather over the next 5 to 10 days, ice cover will continue to grow rapidly on the lakes, with Lake Winnipeg likely freezing up by the middle to end of next week. This will effectively shut off the lake effect machine for the season, and will also allow invasions of cold air to spread into southern Manitoba unmoderated by the lakes. Like it or not, winter is here folks! 

Lake enhanced snowbands may make for tricky morning commute

Snowfall warning issued
for areas south of MB lakes

A cold northerly flow of Arctic air moving over the open waters of Lakes Winnipeg and Manitoba will set the stage for the development of lake effect snowbands this evening which will likely persist tonight into Wednesday. The north to south snow bands will be quite narrow and localized, but could be fairly intense with local snowfall accumulations of 10-15 cm possible within these bands tonight into Wednesday.  Off Lake Winnipeg, the main snowband is expected to set up through Selkirk and eastern Winnipeg into the Niverville area although the band may drift from time to time and fluctuate in intensity. Off Lake Manitoba, a lake effect snowband is expected to set up through Portage La Prairie to just west of Carman to the Morden area. In between these snowbands, occasional light snow or flurries are expected tonight into Wednesday morning with 2-5 cm possible. This will likely make for a slower commute Wednesday morning especially under the heavier snowbands which could be affecting east Winnipeg early Wednesday. A snowfall warning is in effect for areas immediately north, east and west of Winnipeg due to these expected heavier snowbands.

Mild pattern coming to an end.. colder weather on the way this weekend through next week

6-10 day CPC outlook for next week shows
massive outbreak of below normal temps
over central and eastern NA

The extended period of mild weather we've been enjoying across southern Manitoba over the past month will be coming to an end this weekend as a large scale change in the upper weather pattern drives cold Arctic air southward over the next week or two. The change in the weather pattern will be heralded by a storm system tracking across Manitoba tonight into Friday that will bring some rain across the south along with increasing winds and one final shot of milder temperatures. As the system pushes east into Ontario, it will drag a cold front across southern Manitoba Friday afternoon with winds shifting into the northwest. These winds will bring in colder air Friday night into the weekend with temperatures remaining below freezing. Fortunately, it looks like the cold weather won't be accompanied by a lot of snow, although there will likely be bands of lake effect snow off the Manitoba lakes at times, as well as occasional flurries over southern MB. The cold weather pattern is expected  to persist through next week with generally dry conditions and perhaps an occasional dusting of snow with weak impulses passing through from time to time. Currently, no major storm systems are forecast to impact southern Manitoba over the next week which would minimize the chances of a significant snowfall. However, with this prolonged change to cold weather, it will only be a matter of time before a system brings the first widespread snows across southern Manitoba. Until then, bundle up!   

Nice fall weather this week

Temperatures will be running well above normal this week over southern Manitoba as an upper ridge of high pressure builds over the eastern Prairies. Sunny skies and gusty south winds Tuesday will send temperatures into the mid to upper teens, with lows 20s likely across SW Manitoba.  On Wednesday, clouds will increase ahead of a weak system crossing southern Manitoba that may trigger some scattered showers by afternoon or evening. Temperatures however will remain mild in the mid to upper teens. Sunshine will return for Thursday and Friday with temperature again in the mid to upper teens, some 10C above normal for late October.  Slightly cooler conditions are expected early next week, although there are no indications at this point of a change to a prolonged below normal temperature pattern through the end of October.     

Big change in the weather pattern Friday into the weekend.. strong winds, colder temperatures and possible snow..

Wind and wave impact maps for south basins
of Lakes Winnipeg (right) and Manitoba (left)
Severe impacts are possible Friday Oct 3rd
along south shorelines (in red)
(image from province of Manitoba)

It was a pleasant Thursday over the Red River valley with mainly sunny skies and afternoon temperatures up to 19C. But a major change in the weather is arriving tonight in the form of a strong cold front that is pushing across western MB late this afternoon. Showers and even some isolated thunderstorms will accompany this front this evening, followed by a northwest flow of much cooler air tonight into Friday. Friday will be a much colder day, with temperatures some 10-13C colder than today along with occasional rain or drizzle and strong northwest winds gusting to 70 km/h. The rain may even mix with some wet snow over higher elevations of the western RRV Friday. Northwest winds will be especially strong over Lake Manitoba and Lake Winnipeg overnight into Friday morning with gusts to 80 km/h at times. The province of Manitoba has a issued a severe wind alert for Lake Winnipeg and Lake Manitoba warning that strong northerly winds and significant wave action may cause lake levels to rise up to 5 feet over the south basins. Note that lake levels are higher than normal due to excessive summer rainfall, especially over western MB. Lake Manitoba is at 814.2 feet while Lake Winnipeg is at 715.6 feet above sea level. The higher than normal lake levels together with strong wave and lake seiche action will lead to shoreline erosion concerns particularly along the southern and eastern shores of the lakes.

Video:  See video footage of waves at Twin Lakes on southeast shore of Lake Manitoba Friday. (from CBC)

Snowy scene Friday afternoon near Lake Brereton, MB
in the Whiteshell Park area, just one week
after experiencing 30C temperatures 

As the main precipitation shield from this system pulls away Friday, narrow bands of lake effect showers will develop over and to the south-southeast of the MB lakes. In fact, it's possible these lake effect showers may change over to snow inland from the lakes as temperatures drop Friday night into early Saturday, with the potential for accumulating snow in some narrow bands southeast of the lakes. Cold and blustery conditions will persist through the weekend with temperatures some 5-10C below normal for early October.