Sunday, December 03, 2017

Snow on the way Monday as pattern changing storm system impacts southern MB and NW Ontario. Colder weather to follow..

Forecast map valid midnight Tuesday shows strong winter storm system near
Thunder Bay with strong winds and snow on backside of system. Low will
track from South Dakota and increase in intensity as it heads northeast
A storm system tracking across South Dakota tonight will move into Minnesota Monday and intensify as it heads into NW Ontario Monday night into Tuesday. This system is expected to bring snow to southern MB Monday, with the highest amounts expected near the Ontario border where 10-15 cm is expected by Tuesday morning. For Winnipeg and the RRV, 5 cm is expected with up to 10 cm for eastern and southern areas (Steinbach, Emerson, etc)  However, northerly winds are expected to increase Monday afternoon into Monday night which will lead to deteriorating conditions due to blowing and drifting snow with poor visibilities. Temperatures will also be falling into the minus teens Monday night with little recovery Tuesday. Cold weather is expected for the rest of the week before some moderation by week's end. So be prepared for a return to winterlike conditions for the new work week after a pleasant weekend and mild end to November.  

Friday, December 01, 2017

Mild weekend will give way to colder weather next week as upper pattern shifts

The mild weather of the past week or two will continue for the upcoming weekend.. but changes are brewing by early next week as the upper weather pattern changes. The mild weather this past week has been the result of an upper "zonal" flow which brings milder Pacific air across the Prairies while preventing cold Arctic airmasses from advancing south. This pattern will persist over the upcoming weekend but will begin to change to a more amplified "wavy" upper pattern next week which will allow colder air from the Arctic to advance south into southern MB.  The transition to this colder pattern will be marked by some snow Sunday night into Monday with a few cm possible* (see UPDATE below), before northerly winds bring in colder air Monday afternoon into Tuesday.  Temperatures will drop into the minus teens through mid week before some moderation by the end of the week as temperatures rebound back to normal (or even above normal) by mid December.

After that.. there is some uncertainty in how the upper pattern will evolve over Manitoba. The current thinking is that the upper pattern leading up to Christmas will be dominated by an upper ridge over the west coast and  troughing over the Great Lakes/eastern NA.  This would place Manitoba in a northwest upper flow which generally means below normal temperatures here with occasional very cold outbreaks. However, the intensity and duration of these cold snaps will depend on the strength and location of these upper features. At this point, the core of the coldest air is expected over eastern North America which would imply occasional but transitory cold snaps over southern Manitoba modified at times by periodic clipper systems. Until then, get ready for a return to colder weather this upcoming week.

UPDATE (Sun Dec 3):  Storm system will be intensifying overnight through Monday as it tracks across northern Minnesota into NW Ontario. Current guidance indicates the bulk of snow with this system will fall over SE MB into NW Ontario, with Winnipeg and RRV on the western flank of the snow shield. Snowfall from this system will range from 5 cm in the RRV to 10-15 cm closer to the Ontario border overnight through Monday. Increasing winds Monday afternoon into Monday night along with falling temperatures will produce worsening traveling conditions especially south and east of Winnipeg with blowing and drifting snow likely.  

Sunday, November 26, 2017

Mild week ahead.. November ending on a mild note after cold start

After a cool weekend, milder weather is set to return to southern Manitoba Monday as another clipper system brings in a shot of warmer air from the west. Temperatures are expected to climb above freezing again across much of southern MB Monday with afternoon temperatures near +3C and up to +7C over snowfree and downslope areas.  Mild weather last Friday eroded a lot of the snowpack over far southern and SW MB, where a lot of bare ground is now becoming exposed even just south of Winnipeg.  This will make it easier for mild temperatures to surface, eroding even more of the snowpack over the next week.   Tuesday will see cooler temperatures return, but will still be near or above normal (normal highs now are -4C)  Temperatures are expected to remain above normal the rest of the week with highs near or above the freezing mark through Friday.  So after a frigid start to November (7th coldest start on record over the first 10 days), the month will end up on a mild note with above normal temperatures likely persisting into the early part of December.

Sunday, November 19, 2017

Clipper system brings brief warmup Monday, then getting windy and colder again by evening

A fairly intense clipper system will track through the Interlake area Monday bringing a brief warmup to southern MB as gusty southwest winds push our temperature above the freezing mark (+1C) by afternoon. There could be a band of snow and/or freezing rain ahead of the warm front Monday morning, but accumulations look minimal over southern MB. The bulk of snow will be associated near and north of the clipper system across the northern Interlake and central MB where 10-15 cm is possible. As the system tracks east towards Ontario later in the day, winds will shift into the northwest and increase to 40G60-70 kmh by evening over southern MB, with temperatures falling below freezing along with occasional snowshowers and local blowing snow at times. Road conditions will become slick as the melting conditions of the afternoon quickly freeze up Monday evening. We could see a cm or 2 of snow in the wraparound behind the clipper system before things clear out by Tuesday morning. Colder conditions will return through mid week before a brief moderation again by late week with another clipper system.

Saturday, November 11, 2017

Milder week ahead.. but changes loom for late week

After a frigid start to November, the weather pattern is expected to moderate this upcoming week with temperatures more typical of mid November. The first 10 days of the month have averaged -8.8C in Winnipeg, some 7C below normal for the time period, and the 7th coldest start to November since records began in 1872. The past week featured the coldest Nov 9th on record when the temperature fell to -23.7C at Winnipeg airport, with a record low maximum of only -11.4C. This cold start is in sharp contrast to November 2016, which had the warmest start to November on record at +7.0C, an astonishing 16C warmer than this year!

The good news is that temperatures will be a lot more tolerable this week as the persistent Arctic airmass moves off allowing milder air to move in. Conditions look pleasant for the Bombers game Sunday with partly sunny skies and afternoon temperatures near -5C with light winds. Milder temperatures will move in for the new week with temperatures climbing above freezing by Tuesday (high of +2C)  Generally seasonal temperatures are expected through mid week (highs near freezing) before a storm system moves in Friday bringing windy and colder conditions by next weekend.  Until then, enjoy the milder weather this week!