Friday, February 06, 2009

Gusty winds Saturday morning.. storm threatens messy mix for Monday/Tuesday

A fast moving low pressure system over the Northern Plains will track east of MB overnight, bringing a quick shot of gusty northerly winds and some light snow overnight into Saturday morning over southern MB. The cold winds gusting to 60 or 70 km/h will likely produce areas of blowing and drifting snow in open areas particularly through the Red River Valley south of Winnipeg. The gusty winds will bring a brief shot of colder air Saturday before milder air returns for Sunday.

Attention then turns to a storm system that is forecast to develop over the southern Rockies Sunday into Monday. This system is expected to track into the northern Plains Monday into Tuesday bringing a mixed bag of wintery weather to North Dakota and southern MB. At this point it appears that this system will draw up enough mild air to bring an area of wet snow or rain into southern MB late Monday into Monday night and continue into Tuesday. Uncertainty in the track, intensity and precipitation phases of this system makes it very difficult to forecast what will be in store for Winnipeg and southern MB with this event.. but the potential is there for 10-20 mm of mixed precipitation throughout the Red River valley Monday into Tuesday. Stay tuned for futher updates on this developing situation.


  1. Rob as of right now do you see the potential for extended period of freezing rain between the snow and rain mix???

    Are all the computer model showing it warm enough to be all rain???

  2. I think there will be a risk of freezing rain with this system, particularly Monday afternoon into Monday night as warmer air aloft moves in while surface temperatures remain near or below freezing. But the extent of the freezing rain will depend how long we maintain those subfreezing temperatures at the surface. Tough to say with a mild southeast surface flow developing but it may be a few hours worth.

    Overall though, I remain underwhelmed by what the models are showing with this system. Looks like a warm system with minimal cold advection to intensify it. In fact.. most models show the low weakening as it gets closer to us. Ppcn phase will be a problem.. but looks like wet snow/freezing rain developing Monday afternoon/evening changing to a rain/frzg rain/wet snow mix Monday night/Tuesday morning then back to snow Tuesday afternoon/evening for us. That will reduce overall snow amounts, especially here in the RRV and SE MB. Greater snowfall amounts possible over western MB in the colder air and higher elevations.

  3. FWIW.. here's a link showing pcpn phase for the next 84 hrs from the NAM.

    As you can see.. NAM is forecasting straight freezing rain moving into RRV Monday morning changing to rain in the afternoon/evening.

  4. This system just keeps getting warmer and warmer. The latest model runs are showing virtually no snowfall east of a Portage-Morden line. 850mb temperatures are now forecast to be between +2 and +4 for most of the event. At the beginning there is a strong risk of freezing rain. We could be in for significant icing if surface temperatures stay below freezing.

    This will be a bizarre scenario if the models verify. Does anyone know the last time this much rain feel in Manitoba during early February (assuming the models are correct)?

  5. Daily rainfall extremes around this time of year are only around 1-2 mm. If we get the 5-15 mm of rain as models currently advertise, it will be a record rainfall event for this time of year.

    Not what the flood forecasters want to hear..

  6. Bad news for flood forecasters indeed.

    I still have a hard time believing how much rain is being forecast. The models have been consist with it, so one can only assume it is a good forecast. I look forward to seeing what the models say tomorrow.

  7. The whistling winds just started in downtown Winnipeg a moment ago.

  8. Latest GEM/GLB models show area of freezing rain moving into Winnipeg from the Dakotas early Monday morning changing to rain by the afternoon as surface temperatures rise above freezing. We could see several hours of freezing rain giving 2-5 mm of ice before another 5-10 mm of rain Monday afternoon. Pcpn becomes light Monday night into Tuesday over Winnipeg/RRV with about 2-5 mm of light rain or drizzle, before colder air moves in later Tuesday giving us 5 cm of snow Tuesday night into Wednesday. More significant snowfalls possible over higher elvations of SW MB along SK border through this event. The snow will be wet so threat of blowing snow is reduced. Whatever the phase, water equivalent amounts from Monday through Wednesday with this system could be in the 10-25 mm range over the RRV. So although snowpack will be reduced, water content will go up.

    Still lots of uncertainty with this event as NAM/GFS is a little slower on onset of pcpn into southern MB, and has less QPF over us keeping bulk of pcpn over North Dakota. But it's looking more and more like a rain/freezing rain event for RRV/SE MB and more of a wet snow/frzg rain event for areas further west. Stay tuned.

  9. Thanks for the update Rob...

    The GFS is showing a fairly similar situation to what you just described. However I think the GFS has the duration of the event too long. It is advertising nearly three straight days of rain, freezing rain, and snow. Maybe it is right, but from my experience the models like to drag out these events a little too long.

  10. There have actually been a few rain producing Colorado lows to affect Winnipeg in recent memory. One occurred in February 1998 during the 97/98 'super el nino'. We received a mix of rain and snow I believe. The next occurred in late february 1999. Parts of the city received significant rain. In fact the rain associated with the '99 storm helped take out our snowpack by the end of February. That was on of the most glorious early springs we had in Winnipeg. What appeared to be a clear trend towards warmer winters and earlier springs fell flat on its face once the 00's rolled in... sigh.

  11. A correction... the second storm actually occurred in Feb 2000. Gorilla wx station shows 17.3 mm for feb 25/00.

    Btw... EC updated the climate archive page. I can no longer find the daily data organized into each month.

  12. ...Although Feb 25 isn't as impressive a date for heavy rain, as Feb 8 will/could be.

    Latest model runs have been showing 20 to 25mm of accumulation for most of southern Manitoba. I saw a GEM run that showed 40 to 50mm of accumulation over western Manitoba, but frankly I just don't buy that for a second.

    I will already predict that this will be a "now casting" event. The models are showing surface temperatures of about 0.0 to +0.5 degrees, and 850mb temperatures of 0.0 to +1.0 for RRV and SE MB for most of the event, which makes a forecast impossible. If the temperature is off by 1.0 degrees, were are talking about the difference between snow and rain or rain and freezing rain or freezing rain and snow. This could be the most difficult forecast of the year!

  13. Some Winnipeg rainfall stats for February..

    Feb days with 5 mm or more of rain..

    Feb 25 2000.... 20.0 mm
    Feb 25 1998.... 12.5 mm
    Feb 26 1998.... 10.5 mm
    Feb 23 1958.... 7.6 mm
    Feb 21 1877.... 5.8 mm
    Feb 22 1996.... 5.6 mm
    Feb 6 1878.... 5.1 mm

    Since 1873, there have been only 7 days in February with a daily rainfall of 5 mm or more. Only one occurred before the third week of the month.. that was way back in 1878 during our warmest winter on record (an exceptional El-Nino winter ) If this event gives us the predicted 10-15 mm of rain Monday into Tuesday, it will be a rare event indeed for this time of year.. especially for a non El-Nino year!

  14. I hear ya Scott!
    I can already hear Environment Canada ripping there hair out!

    Well Environment Canada forecast for Winnipeg and area for Monday is
    Rain or snow and Windy

    For Tuesday it is showers!!!
    hmmmm..... only time will tell!

    Is it me or does system actually seem to retrograde back to the west on Wednesday??
    This system could be with us for quite some time~

  15. Hey everyone!
    You should read the "grand forks weather discussion" posted this afternoon!

    It gives a very detailed description of what might be heading our way!

  16. Daniel..

    In July 2008, the climate archive site for Winnipeg was changed from "Winnipeg Richardson Int'l Arpt" to "Winnipeg Richardson AWOS". It's the same observing site, but the AWOS site has no climate archive history for YWG (I know.. very confusing). To access YWG climate data, you have to ask for the "Winnipeg Richardson Int'l Arpt" site from July 2008 back. Monthly summaries are available from 2007 back to 1938.

  17. Scott.. yes, nowcasting will be the only way to give more precise details on what this thing will bring. We have a general idea from the models, but as you say.. subtle differences in temperature profiles and precipitation development will have a large impact on precip type and amounts. Sure will be interesting to see how this unfolds..

  18. Special weather statement issued for all of southern Manitoba !

    Also a winter storm watch issued for North Dakota for a heavy ice event!

  19. I have a tough time in seeing how the warm air will work it's way into Southern Manitoba!

    The NWS in Grand Forks thinks the rain / snow line will be south of Grand Forks for most of the day on Monday which ensure that Southern Manitoba stays in heavy freezing rain or snow!

    Is there still the potential for a heavy freezing rain event here in Southern Manitoba???

    This will be a VERY tough call.....

  20. The latest NAM run is very interesting. It basically shows Winnipeg running a fine line between a crippling snowstorm, and a "Montreal style" ice storm. Right now Winnipeg is right between the two, with extensive rainfall expected. Should the temperature deviate mere tenths of a degree, the city could be crippled. The NAM also shows 32mm of accumulation, which is very bad news.

    Although this storm is really quite exciting for weather enthusiasts, we should probably stop for a second an consider the ramifications. NWS in Grand Forks is already predicting major flooding on the Red River. This system is sort of like the early April storm in 1997. It dropped a large amount of precipitation on the Red River Valley, sealing the flood deal. If this storm does go through it will mean an extremely serious situation for Red River Valley residents. I am by no means a hydrologist or river forecaster, but I can see what kind of situation is setting up here. However I am not trying to alarm anyone either, just trying to realize the potential consequences of this storm.

  21. I wonder why the Special Weather Statement issued at ~1630 yesterday was retracted and now reissued at 0430 today with updated formatting but no apparent change in content.

    As a photographer and weather enthusiast I'm rooting for a good storm, but as a resident of the city I'm hoping it blows over. Such conflicted interests!