Friday, November 28, 2008

Strong clipper to usher in cold blast next week

The weather has been decidedly benign over the Prairies this month, with many places still without a snowcover. In fact, take a drive down Highway 75 from Winnipeg and you'll see little or no snow on the ground by the time you get to Morris.  Likewise much of southern SK and southern AB remain snowfree. The lack of weather systems affecting the Prairies this month has meant little precipitation as well as above normal temperatures, especially over the western Prairies. Things will change next week however as an intensifying Alberta clipper tracks across the Prairies, bringing a band of snow with it, followed by a strong push of cold air behind it. 

Models are indicating this storm system will develop over Northern Alberta next Monday (Dec 1st) moving into the MB Interlake area on Tuesday (Dec 2nd).  The storm system will be preceded by a push of mild Pacific air that will send temperatures well above normal over the southern Prairies Dec 1st-2nd.. especially over snowfree areas. North of the storm track however, a band of snow will be moving across the Prairies pushing into central and southern MB on Tuesday. At this point, models are indicating the bulk of the snow (10-15 cm) will fall mainly north of Winnipeg through the Interlake area and central MB. However, the snow could push further south with a more southern storm track. As the storm moves east into Ontario, cold northwest winds behind it will draw much colder air from the Arctic over southern MB, bringing temperatures into the minus teens for mid to late week, into next weekend.     

Monday, November 24, 2008

NOAA releases winter outlook

NOAA forecasters in the US have released their outlook for the upcoming 2008-09 winter. Their outlook indicates more variability in the weather this winter, with no clear signal for warmer or colder conditions this winter over much of the US. Data suggests only the Mississippi Valley having slightly better odds of a warmer than normal winter. Elsewhere, including the northern Plains, there is not enough predictive correlations to say what kind of winter to expect this year. This is due to the absence of an El Nino or La Nina this year in the Pacific, which historically provide better skill in predicting winter temperature and precipitation patterns, especially in the western US. As a result.. other climatic patterns will influence our winter this year, including the Arctic Oscillation (AO) and North American oscillation (NAO), although these patterns are harder to predict long term, and have less predictive skill to our overall winter than the Pacific ocean patterns. All we can say this year for the upcoming winter in Manitoba is "We'll have to wait and see". Environment Canada will release their 3 month winter outlook for Canada on Dec 1st.

UPDATE: (Nov 27): The NWS office in Grand Forks has released their own local winter outlook for North Dakota based on climatological patterns for the Northern Plains. Their prediction calls for a generally colder than normal winter for the Red River valley, with above average snowfall. Overall, they expect a lot of variability this winter (i.e. roller coaster pattern) with a couple of distinct cold periods.. one from early to mid December, and another from late January to mid February. They also point to a cooler than normal spring.

Dry and pleasant rest of November

The weather has been very quiet here in Southern MB the last couple of weeks, and it appears the quiet weather pattern will stay with us the rest of the month. According to long range models, no major precipitation bearing systems are forecast to affect us through the end of November, which will be a disappointment for those looking for snow, but good news for those not ready to put up with winter's worse just yet. Snowfall has been meager over southern MB this month since our first major snowfall of the season back on Nov 6-7th. Here in Winnipeg, we've had just 2-3 cm of minor snowfalls since the 8 cm in the Nov 6-7th storm. In fact, much of the Red River valley south and east of Winnipeg still has little or no snow on the ground.

Temperatures will also be near to above normal for the rest of the month, with daily highs in the minus 2 to minus 4 mark the rest of the week into the weekend (with above freezing temperatures possible over snowfree areas). So it appears that after a somewhat early start, Old Man winter has taken some time off. Is he resting up for a nasty return visit in December? Or is he just getting old and tired? Time will tell. At this point however, it appears that a major snowfall is not in the cards for southern MB for the foreseeable future.

Saturday, November 22, 2008

Manitoba snowlovers, look away

Our weather has been so boring here lately, I thought I'd post an image showing what heavy snow looks like. This is a photo of a van in Arkona, Ontario buried in over 76 cm of snow that fell during a major snowsquall off Lake Huron Thursday night into Friday morning. (Arkona is located just west of London, Ontario) The snow came down so heavy so fast that numerous motorists were stranded on highways in the area, and emergency officials were forced to use SUVs and snowmobiles to rescue stranded travellers. There were unofficial reports of snow 4-5 FEET deep (120-150 cm) in places. Snowsqualls are a fact of life to the lee of the Great Lakes, but even long time residents in the area say they had never seen so much snow falling in such a short period of time as Thursday night. Given the accumulations, snow was likely falling at 10-15 cm/hr at times during the event. For additional photos on this event, click here and here.

Wednesday, November 19, 2008

Manitoba Lakes Ice Cover

I had a request asking about the status of the freeze up on the Manitoba lakes. The image posted here is a MODIS satellite photo taken Monday afternoon Nov 17th showing the latest ice conditions on our lakes. Dark blue areas are open water, still evident over much of Lake Winnipeg (right) while light blue (turquoise) areas are snow covered and/or ice areas. Grey/white areas are clouds (notice the impressive lake-effect clouds off the lakes) while beige areas are bare ground and green areas are forested. The image shows that much of Lake Winnipegosis is ice covered, except for an open area in the far north, while Lake Manitoba appears to have thin ice forming over much of the basin. I suspect Lake Manitoba will be frozen over by this weekend given the upcoming cold weather.

These high resolution satellite images over Manitoba are available at the MODIS remote sensing website. You can monitor the progress of the lake freeze up with daily updates on this site.

Cold but dry next few days

A large Arctic ridge of high pressure will build over the Prairies today and Thursday bringing cold but dry conditions to southern MB over the next few days. The exception will be over and south of the MB lakes where some lake effect snow is possible today into Thursday. Elsewhere conditions will be dry with generally clear skies tonight through Friday.  Temperatures will be several degrees below normal for mid November with lows in the minus 15 to minus 20 range and highs around minus 10.  A moderating trend is expected over the weekend as a southerly flow develops ahead of another Pacific disturbance tracking across the Prairies. This system may bring some snow over southern MB by the end of the weekend.

Friday, November 14, 2008

Dull November weather continues

The weather sure has been dull here lately, with little in the way of sunshine since winter arrived last week. Other than some sunshine on Remembrance Day, the weather has been generally overcast and dreary since Nov 5th, or 8 of the past 9 days. There is hope that some sunshine will break through the clouds for awhile on Saturday, but another clipper system moving through southern MB Saturday night into Sunday morning will spread more cloud and a chance of snow, especially north and east of Winnipeg. Dry conditions are expected Monday before another threat of flurries by Tuesday. November can be a very cloudy month as colder air moves over still open lake waters, producing frequent clouds even in high pressure ridges. Or in other words.. No sun, no warmth, no wonder.. November!

Friday, November 07, 2008

Winter storm wallops southern MB

After some exceptionally nice weather to start the month, Mother Nature decided it was time to remind southern Manitobans that it's November in the Prairies. The first major winter storm of the season blasted southern MB Thursday and Thursday night with a variety of wintery weather, bringing snow, freezing rain, ice pellets, strong winds, as well as heavy rain to the area. In Winnipeg, the storm began with rain Thursday morning that changed to ice pellets driven by 50-70 km/h winds through the afternoon and evening. Ice pellets accumulated around 2-3 cm by evening along with some freezing rain. Overnight, precipitation changed to snow with 2-4 cm falling on top of the icy mess from the night before. In total, about 25-35 mm of melted precipitation fell over the Winnipeg area, with general snowfall accumulations of 5-8 cm across the city by Friday morning. Heavier amounts of snow were reported further west along the western Red River valley and MB escarpment, with 15-25 cm reported from the Pilot Mound area through Portage La Prairie. The snow and ice left many roads in poor driving conditions across the Red River Valley and SW MB, with travel not advised on several highways into Friday morning.

Further south and east of Winnipeg, precipitation was mostly rain Thursday, with significant amounts of 30-70 mm reported across portions of the southern Red River valley. Overall, an abrupt initiation to winter weather for residents of southern MB!

Wednesday, November 05, 2008

Winter Storm Watch issued for Southern MB for Thursday/Thursday night

EC has issued its first winter storm watch of the season for the Red River valley, Interlake and SW MB areas.  A storm system intensifying over the Dakotas Thursday will spread an area of rain over southern MB through the day Thursday that will change to snow over higher elevations west of the Red River valley. Rain will change through a period of ice pellets and possible freezing rain along the Red River valley Thursday evening before changing to all snow Thursday night. The transition to snow will be slowest southeast of Winnipeg which will keep snow amounts down in those areas. Snowfall totals with this system will be tough to forecast given the uncertainty in timing and location of the rain/IP/snow line, terrain effects, pcpn rate intensity (which can affect rain/snow transition), as well as melting effects of the still warm ground. At this point, preliminary snowfall accumulations by Friday could range from trace-2 cm over SE MB, 5 cm over Red River valley including Winnipeg (perhaps 10 cm north and west of the city into the southern Interlake), and 10-15 cm along the western red River valley/SW MB areas with the highest amounts over higher elevations.  Stay tuned for further updates on this developing situation..

Monday, November 03, 2008

Warmest November day in over 30 years

It was a record breaking mild day across much of southern MB today, as southerly winds pumped in an unseasonably mild airmass from the US.  Temperatures reached 18.8C at Winnipeg airport this afternoon, eclipsing the old record of 18.3C for Nov 3rd, set back in 1903.  The 18.8C reading is also Winnipeg's warmest November temperature since Nov 5 1975, when a high of 23.9C was recorded, Winnipeg's warmest November temperature ever.  The 18.8C reading ranks as Winnipeg's 7th warmest November day since records began in 1872. It was even milder southeast of Winnipeg with 20C readings in places like Sprague and Steinbach. Amazing weather for early November in southern MB! 


Sunday, November 02, 2008

Mild start to November.. snow by Thursday?

It’s been a nice start to November with mild temperatures and dry conditions. The mild weather is expected to continue for the next couple of days before a change to wetter and colder conditions by the end of the week. In fact, the GLB model is indicating the potential for the season’s first significant snowstorm affecting southern MB by Thursday. In the meantime, enjoy these next few days with well above normal temperatures in the low to mid teens and sunny to partly cloudy skies. Things will start to change by midweek as an area of low pressure develops over the Dakotas on Wednesday spreading an area of rain over southern MB.  As the storm system tracks slowly into Minnesota, colder air on the backside of the storm will change the rain to snow over southern MB for Thursday.  At this point, it’s too early to say how much snow we’ll get with this storm, if any, as things are still 5 days away. Some models are indicating the bulk of the precipitation will fall as rain over Winnipeg with some minor wet snow on the back side of the departing storm for Thursday. Other models (like the GLB) are indicating the storm stalling and giving us a significant snowfall Thursday.  At this point, all we can say is the potential is there for our first snowfall by Thursday, but we’ll have to stay tuned to see how the models trend over the next couple of days to have a better idea. My gut feeling is that the GLB is overdoing the snowfall with this system over southern MB for Thursday, but perhaps that’s more wishful thinking than anything scientific (it’s too early for snow for me!) Stay tuned..