Thursday, May 14, 2009

Clipper to bring snow to western MB and Interlake.. rain south

An Alberta clipper will track through the Dakotas overnight and bring an area of rain and snow to southern MB tonight into Friday morning. Rain will spread into southern MB from the west tonight, but will change to snow over the higher elevations of western MB through the Riding Mountain and Duck Mountains areas. Snow will be heavy at times tonight in these areas with 10-20 cm possible, especially along the eastern slopes and over higher elevations. The highway 5 corridor from Dauphin to Roblin and Highway 10 corridor north of Hwy 5 through Ethelbert and Pine River are under the gun for heavy snow tonight. This snow will track east into the central and northern interlake regions overnight into Friday, bringing heavy snow to the Hwy 6 corridor mainly north of Lundar. Further south, precipitation will arrive in the form of rain tonight, with about 5-10 mm of rain possible in Winnipeg and the northern RRV overnight into Friday morning.


  1. Rob
    With the temperatures hovering around 1 C in Winnipeg and area overnight ,what are the chances that this could turn into snow !

    Could anyone tell me why sometimes it will snow sometimes when it is
    1-3 c outside???
    Other times it has to be below freezing.

  2. I think pcpn for Winnipeg will be mainly rain as the air above the surface will be too warm for snow. However, there's a chance that the rain could change to snow behind the system Friday morning as colder air moves in on the backside of the system.. The bulk of the pcpn should be east of us before then however.

    As for snow when it's +1-3C, it all depends on how warm or cold the air is above the surface. If the air aloft is cold enough, then snow can reach the surface even if it's just above freezing at the ground. Google "precipitation type" for more info on how temperature profiles determine what kind of precipitation falls.

  3. GEM model has been steadily increasing precip amounts with this clipper. Yesterday it showed a 15 mm QPF max near Dauphin by 12z Friday, then 21 mm max last night, and now 25 mm bullseye with this morning's run, again near YDN. NAM is a little less intense and a little further north with QPF area.. with a 15 mm max near Roblin by 12z. GEM may be a little overdone, but assuming 10:1 snow:water ratios, you could be looking at 10-20 cm through the area.

    Snowing pretty good right now along and north of Yellowhead Hwy in SK which will spread east through the day reaching western MB by late afternoon. Sigh.. mid May and we're still dealing with snow in southern MB:(

  4. 12z GFS paints some high qpfs around CYWG and areas north from 05/15/09 6z onward...where will the rain/snow line end up?

    I think we might get snow, especially from midnight onward! May 11th snowstorm repeat?

    Dewpoints are at -4 right now...please climb above 0!!!

  5. Snowfall warning already issued for the areas of southern Manitoba!

    May 11 2004 snowfall from what I understand was EXTREMELY RARE for the area!
    I guess all the planets have to align for that to happen

  6. I heard that the planets were aligning themselves again! ha!!! It better not happen! The Rain/Snow line location is kind of scary!

  7. Based on the available model data.. I have to agree that the rain snow line *should* stay north of Winnipeg. With 850 hPa temps above zero and strong warm air advection.. the bigger worry for Winnipeg would be freezing rain potential. I would especially be concerned if temps would quickly spike down tonite... however skies have already clouded over so this is not as likely.

    I think the higher precip amounts are supported by the fairly impressive dynamics that will come into place. Nose of 55 kt LLJ (RUC) will interact with right entrance region of upper jet. Instability parameters appear weak for elevated (upright) convection.. low level moisture will be decent with 850 hPa dewpoints of 6 C just to our south.

    However, slantwise convection and banded precip is possible. Depending on slope of isentropic (theta w and e) versus momentum surfaces, CSI (conditional symmetric instability) may be present. Using Q vectors, frontogenesis (which is very likely present) could be confirmed and placed. The interaction of direct thermal circulations (rising motion in warm air/ sinking in cold) from frontogenesis and CSI often leads to enhanced precip bands. We will likely see that overnite.

    Very strong baroclinic zone along US border will re-establish itself by Monday. Tuesday overnite looks *very* interesting. Stationary WSW to ENE front, LLJ, moisture and instability all will be present according to GFS. Looks like a heavy precip corridor is establishing itself over southern Manitoba.. with several rounds of MCSs passing over us.

  8. Even places like Portage La Prairie will get 5 - 10 Cm of snow...

    You thought yesterday was a miserable day....just wait tomorrow with a wind blown rain snow mix with gusts to 70 km/h


  9. Rob!
    Do you see any lake effect snowfall with this system????

  10. Justin H.....
    I see on your live streaming video
    you have "POTENTIAL snowstorm for Winnipeg"

    What are your thoughts on what might transpire for Red River Valley for tomorrow???

  11. As of 10:01pm their is a snowfall warning in effect for Stonewall and Selkirk. It is steadily creaping closer to Winnipeg

  12. Well the rain/snow line remains north of Winnipeg. My fear was never realized...great news!!!

    I put that on my stream because I wasn't sure where the ra/sn would show up.

    Tuesday does look interesting!

  13. Rain/snow line has set up halfway between Winnipeg and Gimli.. likely north of a Stonewall-Selkirk line. Rain/snow line pushes through Winnipeg by midday as colder air aloft moves in behind system, but most precipitation will have pushed east by then.. so snowfall here should be minimal if any. Different story north of us with a good 10 cm through Roblin/Dauphin/McCreary/Interlake areas.

  14. Next week's thunderstorm threat has diminished significantly based on the 12z GFS run. Tuesday has completely flipped around. It looks like another shot of precip will affect our area on Monday, followed by more cooler weather! The flip towards warmer temperatures looks to be in the works for NEXT weekend!

  15. Some snowfall reports north of us this morning..

    Hodgson (east of Ashern)... 27 cm
    Gilbert Plains............. 24 cm
    Moosehorn.................. 20 cm+
    Laurier.................... 20 cm
    Rossburn................... 14 cm

    Reports of up to 30 cm in Russell.

  16. Rob!
    What is the record overnight low for Winnipeg for Saturday morning???