Thursday, October 23, 2008

Taste of winter on tap for Sunday

A strong cold front will push across southern MB late Saturday driving in the coldest airmass of the season so far Saturday night into Sunday across the area. The cold air will be ushered in by strong northwest winds gusting to 70 km/h, with locally higher gusts off the lakes.  Temperatures on Sunday will struggle to reach +3 or 4 degrees, and those gusty northwest winds will make it feel 5 to 10 degrees colder. Most areas in southern MB will likely wake up to see some snowflurries Sunday morning, but localities southeast of Lakes Manitoba and Winnipeg may see heavier bands of lake effect snow Saturday night into Sunday as those cold northwest winds sweep over the open lake waters.  Lake water - 850mb temperature differentials will be approaching 20C by Sunday morning, which is favourable for narrow bands of heavy lake effect snow. Note also that lake levels are running a little higher than normal right now, so northwest gales of 35 to 45 knots over the lakes may produce some shoreline erosion on the eastern shores of Lake Winnipeg and Lake Manitoba. Fortunately it appears this arctic blast will be short lived as lighter winds and moderating temperature are forecast for Monday and Tuesday.  

25 comments:

  1. So with those winds being so strong you think that Winnipeg might actually see those lake effect streamers reach into the city?????

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  2. Due to the strong winds Sunday, I think we'll see multiple streamers coming off the lakes giving lake effect flurries to almost everyone in southern MB including Winnipeg. Within those streamers however, I think there'll be some embedded bands of heavier snow coming off Lake Manitoba and Lake Winnipeg likely west and east of the city.

    For Winnipeg to get a good streamer off Lake Manitoba, we need a 300-310 degree wind direction (WNW). For streamers off Lake Winnipeg, we need a 010-020 wind (NNE). On Sunday, it looks like we'll have a 330 wind (common with cold outbreaks) which would put the heavier bands west of us through Elie and east of us through Beausejour. This shows how a subtle shift in the wind direction can make the difference between scattered cloud and heavy snow in lake effect situations.

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  3. Latest model guidance indicating the potential for low level winds in a 300-310 direction Sunday which would bring the more intense streamers off Lake Manitoba into Winnipeg. Still too early to say for sure, as even a 10-20 degree difference in wind direction would set up the heaviest bands outside the city. But don't be surprised to wake up Sunday with some snow on the ground! Stay tuned..

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  4. The NAM shows the best time frame for lake-effect snow in Winnipeg from 10p.m. on Saturday through to 4 a.m. on Sunday. If it is cold enough there is also the possibility of snowfall after lunch on Sunday.

    Can these bands reach Steinbach? I have never seen them do that before.

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  5. Scott..

    With strong enough winds, a 310 snwoband could reach Steinbach off Lake Manitoba, which is possible Sunday. In addition, Steinbach can sometimes catch a 360 snowband off Lake Winnipeg. Generally though the streamers are more intense closer to the lakes.

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  6. Winds will be a concern on Sunday.. latest GEM guidance indicating low level wind maximums of 50 to 60 knots out of the northwest over all of southern MB. With all that cold air coming in and well aligned winds in the low levels, that could translate to gusts of 80-90 km/h at the surface. In addition, winds will be howling over the MB lakes with gales of 35-45 knots generating wave heights of 6 metres or more. (latest marine guidance indicating potential of 8 metre waves Sunday!) That could lead to some erosion problems on the east shores of Lake Winnipeg and Manitoba. Add a few snowsqualls and you have the makings of a wild and wicked Sunday along the east shores of the lakes!

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  7. Lake effect parameters for Sunday morning showing 850 mb temperatures of -8 to -10C moving over +9C lake waters over the south basins, and +5-7C (est) over the north basins. This gives a 850-lake water temperature differential of 15-19C. This is more than adequate for snowsqualls off the lakes given well aligned low level winds (you need at least a 13C difference for lake effect to develop). One problem for formation of intense single snowbands off the south basins Sunday may be that winds will be TOO strong.. giving multiple weaker bands instead. Will have to see how this develops. Models hinting at significant accumulations Saturday night into Sunday further north along the east shore of Lake Winnipeg from Berens River to Bissett areas due to snowbands off the north basin..

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  8. WOW
    That is gonna be one wicked cold front
    I mean temps are really gonna plummet!
    I mean look at Saskatoon daytime high on Sunday!
    -4 C
    OUCH~
    Even here it is gonna be struggling to get above zero with a wicked windchill

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  9. 8 meter waves on Lake Winnipeg would be something to see.

    Should be an interesting weather weekend to say the least!

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  10. Looks like the strongest winds will be in Regina with wind gust approaching 100 km/h!

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  11. Strongest winds today will be over Alberta and Saskatchewan as cold air advection moves in from the west and 50-60 kt low level jet develops. Those strong NW winds will spread into southern MB tonight and Sunday with the strongest winds likely over SW MB and over/lee MB lakes.

    12Z GEM also showing significant lake effect event off the south basin of Lake Winnipeg Sunday into Sunday night with 25 mm water equivalent by Monday morning. With early season lake effect snow, this could easily equate to 25 cm of snow to the southeast of Lake Winnipeg including the Highway 12/59 corridor from Beausejour up through Grand Beach. Much lighter amounts noted off Lake Manitoba, but I still think there's a good chance of a pretty decent squall setting up between Elie and Winnipeg. Should be an interesting day coming up tomorrow..

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  12. I do have a question I was hoping someone will be able to answer!!

    How is possible for it to snow when the air temperature is 8 C??????
    Look at Yorkton this morning!!!
    8 C and it is light snow!!!! HOW?????

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  13. Probably an erroneous report. Snow is unlikely at temperatures of 8C. Yorkton is an automated station and auto-stations sometimes mistake blowing dust or some other phenomenon with light snow.

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  14. WOW
    I live in St James and is....snowing???
    Hail????
    Maybe some sleet mixed with rain~!!!!!

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  15. yeah, i caught the same heavy rain system that pummeled the St. James area! it looked like hail, snow, and a rain/snow mix!

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  16. Cells have that low topped CB look to them.. perhaps it was some small hail. Even getting some lightning strikes with cells near the Ontario border..

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  17. Okay, I thought I heard thunder a little while ago. The Birds Hill lightning detector showed some nearby. Nice for October. Until tomorrow.

    How about them winds in Saskatchewan?

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  18. Lightning and thunder here in Charleswood at 5:30 pm.. had some brief small hail at 5:25 pm.

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  19. Same here at 5:35 PM in Richmond West.

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  20. Wind Warning for the Southern Manitoba !
    Winds are already howling outside my window here in Winnipeg with winds over 75 km/h

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  21. Local webcams this morning showing some snow on the ground in Morden and Pilot Mound areas.. as well as Grand Forks where visibility is down to 1 mile. Here in Winnipeg, just clouds and blustery winds. Lake effect is minimal so far..

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  22. Nice lake effect bad seems to have developed off of Eastern Lake Winnipeg spreading precip into the Manigotagan-Pine Falls area.

    If snow is falling in it, I wonder how much will accumulate?

    Much smaller and dispersed bands coming off of Lake Manitoba, but ya never know what could happen with that

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  23. Did anyone hear of any peak wind gusts yesterday in southern Manitoba???

    I know Winnipeg airport hit a maximum of 76 km/h !

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  24. Strongest wind gusts reported yesterday across southern MB..

    Victoria Beach..... 89 km/h
    Pilot Mound........ 85 km/h
    Oak Point.......... 83 km/h
    Winnipeg Arpt...... 80 km/h

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  25. We had some lake effect yesterday and last night, but it was far less intense than I was expecting. Must have been too much windshear and not enough low level instability to get the lake effect really going..

    A chilly one tonight with partly cloudy to clear skies and light winds. Look for lows to drop into the -6 to -9C range tonight. (Regina had a low of -14C this morning, even with no snow on the ground!)

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