Thursday, October 01, 2009

System to bring rain south and west of Winnipeg

A low pressure system moving through the Dakotas is spreading an area of rain over southwestern MB this morning. Rain will gradually spread into the Red River valley today but should stay mainly to the south and west of Winnipeg as the system stalls and pulls south. Rainfall amounts of 20-40 mm are forecast over western MB with 10-20 mm possible over the Red River valley south and west of Winnipeg. Areas north and east of Winnipeg should stay dry today into Friday.


  1. How long will we be just spectators to that line of cloudy and windy weather southeast to MplsFargo and the Northwest to Regina?

    Are we protected once again by that floodway West Dike? LOL

  2. Rob!

    Looking at some of the long range models and some of the comments of long range forecasts it looks like the cool weather is here to stay!

    I have a feeling October won't end up being the warmest on record!!!

  3. Rain pushed further north and east than models indicated.. with dry slot cutting off precip over the southwest. Secondary area of rain over eastern ND is moving northwest and should bring additional rainfall to areas south and west of Winnipeg this afternoon into this evening.

  4. Some development back towards the Red Lake region of NW Minnesota that bears watching... it is directly in line with Winnipeg.

    Very impressive elevated convection down over the Twin Cities region. LLJ accelerates this this evening with nose of 55 kt maxima near Emerson... would expect a lot of this convection to be advected into at least the southern RRV given the progged flow over the next several hours.

    This will degenerate into a region of stratiform rain and organize itself parallel to the international border... slowly slumping south as models advertize strong dry push coming in from east. Given that models underestimated NE extent of initial precip and progged configuration of LLJ etc, maybe they are still a bit too SW with precip? In any case, will be a close call.

  5. Impressive push of dry air with sub zero dewpoints really slicing under the warm moist SE flow aloft. Very sharp cut off to precip running from roughly Winnipeg to Duluth with cloud line about 100 km NE of that. Looks like Winnipeg will indeed stay dry as that esterly continues to take control.

    I am always surprised how often Winnipeg finds itself at the edge of large precip events... whether due to a dry easterly flow as in this case or when the LLJ sets up just to our SE. Go figure.

  6. Got another below 0 temperature at the airport this morning!!!

    Rob did you get below 0 C????

  7. I have a question for who ever can answer!!!!

    When CBC does there weather forecast they claim to have Manitoba's only LIVE radar!

    Now is it truly live????
    I see the LIVE sweep of the radar beam...does it actually refresh on each sweep of the beam or is all for show???

    Is CBC radar not the exact same data from Environment Canada???

  8. Daniel "Large precip events" I couln't agree more.. The eastern edge of the prairie and beginning of the heavily forested nw to se line just east of Wpg (Hwy 12 ) appears to confirm that observation at least as to the easterly cutoff.

    That doesn't seem to confirm the westerly cutoff The escarpment/Spruce woods/Spirit sands perhaps. Estevan area Lightning strikes are more prevalent

    Anecdotally, as a previous resident of Beausejour and Camp Shilo i couldn't agree more


  9. Daniel i don't know if it is relative but Wpg is at the bottom of the mid continent. I'm not aware of any significant elevation decrease for at least 400KM in any direction . Uphill , includes most Northerly directions for anywhere land based. The two large northerly lakes are less than 20 feet below us. Lake Wpg is 218 meters. as is James ave Datum.

  10. There is some literature/studies which try to correlate the forest/prairie transition with the boundary of positive and negative moisture regimes (using an index of i] potential evaporation vs actual precip or ii] potential evapo vs actual evapo).

    However, topography and soils have a big say on vegetation patterns as well. Studies suggest the hardwood forests of Minnesota (very similar to those found in eastern Canada) represent a relatively recent invasion of the prairie. Lakes and undulating terrain serve as fire breaks allowing forest to become established wherever moisture is sufficient.

    Here in the RRV the flat terrain allowed prairie fires to ravage the landscape, and trees only became established where there was protection from such events (close to rivers). Soil type is also an important limiting factor... the heavy clay here has poor drainage and is alkaline, favoring the development of grasses.

  11. Yes, we are at the 'bottom of the trough' so to speak in the RRV. We do not benefit from any upsloping here. Whereas parts of SW Manitoba often receive enhancement from such mechanisms (especially when cold/occluded lows track across the northern plains setting up a moist easterly, upslope flow).

    I also think (and this is pure speculation) that there is some forcing mechanism that causes the southerly LLJ to favor areas of the southern RRV and SE Manitoba. Extreme precip events certainly seem to have been more common just south of the TransCanada hwy in recent years. Further research as to the geographic distribution of these occurrences may possibly confirm this.


    I hope the models are correct in showing continued moisture and clouds below 700 hPa backing in from Ontario... we would be dealing with a widespread killing freeze otherwise. Some breaks in the clouds gave me pause, but things have filled in nicely again.

  12. Daniel P

    To answer your question it is likely just for show.. Here in the states I have seen this done many times during weathercasts out of the Fargo TV stations. They will show a radar beam sweep around the Mayville site acting like it is a live radar shot updating as we speak. But of course it isnt.

  13. Dan from NWS!!!!

    I know you like cold weather and you might be in luck because some of the computer models are showing some very cool weather along with some snow flurries next weekend !!!

    Time will tell!!!!

  14. Daniel P

    I have to keep the warm mongers in line :) just kidding of course. Most of you guys are likely from the Manitoba area whereas I am from the southern states so I missed out on years of cold and snow and want to catch up. But seriously I remember growing up I wanted to move to Canada and live in North Battleford or Saskatoon as I noticed the path of most arctic highs drop down that way from the Yukon. Got close... I spent a week up at PSPC in Winnipeg back in 2000 and enjoyed it as part of a forecaster exchange program betwn EC and NWS.

    Time will tell on the winter. I am more of a cold fan than lots of snow. I would prefer about 6-10 inch snowcover and below zero (F) for a month or two...then 60s and 70s for the summer.