Sunday, November 18, 2012

Dry and mild start to the week.. turning colder with some snow likely by Thursday

Generally pleasant and dry weather is expected over southern Manitoba over the next few days as a series of low pressure systems passes to the north of the region.  This will bring a flow of above normal temperatures over the south with daytime highs generally above freezing today through Wednesday. Warmest temperatures will be over far southeast MB which has minimal snow cover, with highs of +5 to +8C possible over the next few days. By Wednesday, scattered showers are possible ahead of  a low pressure system that will be developing over southern SK. This system will drag a cold front through southern Manitoba by Thursday with some snow possible as colder air works in behind it. This doesn't look like a major system at this point, with snowfall amounts of 2-5 cm being forecast by the long range models along with gusty north winds. Still, it will likely be enough to bring wintery driving conditions over southern MB once again, after a period of relatively benign weather. Until then, enjoy the nice weather for the next few days!   

38 comments:

  1. You can see the dramatic difference that lack of snow cover and forested terrain makes in the temperature. Sprague is a
    aleady up to +7c as of 11 am, while snow covered areas of southern MB are still below freezing.

    Even with the snow however, we'll be rising above zero today with that sunshine and SE flow. Nice day!

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  2. Above zero in Winnipeg also now....1.7C at the airport and around 3C pretty much all across town at this hour....definately a nice day.

    Rob, do you think we could get to 5C or 6C today based on current temps and with that sun and SE flow?

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  3. Anonymous.. Yes, I think it's quite possible Winnipeg could hit +5C this afternoon given the sunshine and +10c tempeatures over SE MB and northern MN.

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  4. Sure a variety of temperatures.. Some parts of southwestern Manitoba struggling in fog or struggling to warm altogether. Dauphin -6°C, Brandon -5°C, Portage -6°C, and -1°C Emerson... But it's +7°C in Wasagaming, 4°C Roblin, 3-4°C Winnipeg, and 9°C in Sprague!

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  5. Average snow depth here this afternoon is 10 cm (River Park south) with a range between 8 and 13 cm.

    JJ

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  6. Well that SE flow worked its magic today.. not so lucky was the western RRV and L Manitoba basin that got fogged in. Typically under a SE flow with snow cover, Winnipeg gets quite mild while Portage (which usually benefits from a down-slope flow), gets stuck under an inversion. Btw, without measuring I would estimate approx 6-7 cm of snow for the far south end of the city, with the grass starting to show in some areas around U of M.

    Temperature trends for tonite will be tricky.. with clouds eventually moving in and persistent southerly (10-15 kmh). SW Manitoba and western RRV might see temps actually rise initially, as better mixing and clouds move in along the trough. For Winnipeg, I think its quite possible that temperatures will remain above freezing inside the city proper (temps may fall a bit more at YWG depending on flow and cloud cover). Trough comes thru tomorrow morning with weak cold advection.. however, it will likely be offset by daytime heating. So its not inconceivable that we get 24 consecutive hours of above freezing temperatures for parts of town.

    With warm flow starting up again overnight Monday, that progged snow-depth of 1 cm may not be so extreme - at least for the south end up thru downtown.

    Daniel

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  7. Didn't refresh page before JJ's comment.. I should note that the area around U of M is quite open, so its likely that snow depths there are lower than a more sheltered residential area.

    Daniel

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  8. Ya that's true, snow in the fields seem a little less deep than in yards right now, especially shady spots. 6-7 cm is reasonable

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  9. Temps cooled off quickly to below freezing this evening.. even at the forks. Clouds will arrive within an hour or two, which should stabilize the temperature drop..

    Daniel

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  10. Hi rob the weather network has southern Manitoba getting 15 to 20 cent of snow Thursday. What's your thoughts? Really appreciate your up to date insight!

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  11. Temperatures went as high as 12.1C in Fort Frances, Ontario yesterday... the country's warmspot.

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  12. 15-20cm! Was that on TV? It's only showing 5-10cm on their web site right now for Thursday. Quite often their TV and web site don't agree.

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  13. NWS Dan - The NWS confirmed that their SA to METAR converter is the problem at WPO, mistakingly switching the wind speed and direction when the speed is MM in the SA report.

    They are now working on a fix.

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  14. Re: Thursday snow event

    Models are coming in a bit slower and wetter on this next system over southern MB, with the potential for precip to start as rain over YWG/RRV before changing to snow late Thursday into Thursday night as the colder air works in. Right now, models are generally looking at about 5-10 mm of total precip for YWG by Friday, with about 5 cm of snow. But that will depend on how quickly or slowly the transition to snow is, and there's a chance we could see more snow if the cold air comes in quicker, or the track of the storm is further south.

    There does appear to be a greater liklihood of heavier snow accumulations through the western parklands/interlake areas to the north of Winnipeg. Will keep you updated on this system as the week progresses..

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  15. The 15 to 20 cent is for Brandon it was posted on the website.

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  16. From CBC Manitoba:
    Weather Journal for November 19th
    We could see some showers on Monday. This week's temps will be above the seasonal normal but I'm expecting a cool down by Friday with some flurries.

    Showers today? What?!

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  17. Nice to get another above freezing day. For tonite I wouldn't expect much drop in temps for the city and the airport, with flow already WSW, and high clouds progged to move in by 10 PM. Towards dawn, there will be a 25-30 kt flow at 925 hPa with temps moving back up to 8-10 C. Models suggest inversion holding over snow pack initially, but we should eventually start getting some gusts down to the surface of around 30 km/h.

    With good southerly flow tomorrow and warm air, would lean on some of the higher guidance for temps (RGEM SCRIBE is as high as +6 C). The stronger winds will also allow for faster melting of snow.

    Btw, the snow sensor at the climate station (XWG) laughably estimated an increase in snow-depth both Nov 17th and 18th. Hopefully it won't be a moot point - with 18Z NAM dumping 21 cm of snow for the late week system. It also gives us 5-6 mm of rain between 3-7 AM Thursday.. highlighting the uncertainty with this system.

    Daniel

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  18. Strange. All the models show some form of rain and snow in the THU/FRI timeframe, SCRIBE has it, the Meteocode has POP 60%, but the public forecast text has no mention any precip.

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  19. Garth..

    Blame that on poor automated programming for those long range forecasts. The forecasts for day 3-5 are based mainly on daytime conditions (something like from 7 am to 10 pm) so if models show precip falling during the night hours, it's not mentioned in the forecast. Again, more a problem of poor programming than poor model data. Of course, the public doesn't know of this limitation, so they think there's no precip forecast for the next few days, which of course is not the case.

    Thursday still looks like we'll see something, especially by Thursday afternoon or evening as the colder air deepens and the northerly winds pick up. Still looking at a possible 5 to maybe 10 cm of snow for us, so Thursday evenign and Friday morning commutes will be slippery ones. Euro even came in with 15 cm of snow (assuming 10:1 ratio) for Thursday.. so this could be a significant event for us. Stay tuned..

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  20. Thanks Rob. Yes, I've seen significant events being ignored in the extended forecast before, and it was always during the evening or overnight period. Poor programming and policy.

    On a positive note, I see the Weatheroffice site is planning to update the forecast pages, including showing hourly (3 hour periods) forecast values.

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  21. Hi Rob,

    I've heard that this latest system coming in Thursday could potentially give us up to even 20CM. What do you think are the chances of us getting that much snowfall with this system?

    I've also noticed that signs are pointing towards some very cold air spreading in next week. If this is indeed the case, does this look like anything like a prolonged below normal stretch of cold temperatures going into December?

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  22. Latest GLB model run has sped up the timing of the snow for Thursday, now bringing it into Winnipeg early Thursday morning which is line with other models. They give about 8 cm of snow by evening, after beginning as some rain or freezing rain overnight Wednesday into early Thursday. NAM giving 9 cm of snow by Thursday evening. Winds picking up as well during the day, so things looking dicier and dicier (or icier and icier) on the roads for Thursday.

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  23. Very warm air aloft, with thermal ridge between 850-925 hPa moving in early tonite. With 20-30 kt flow at 925 hPa and SW flow, temps have the best potential for staying up above zero compared to previous days. Uncertainty creeps in by 12Z tomorrow. Most models show stationary front slumping south giving us a ENE flow by dawn.

    Exact position of warm front in question tomorrow, but will likely see a sharp temp gradient from NW to SE. Models show shallow inversion and easterly flow, but with warm advection at and above 925 hPa. Hopefully with easterly trajectory to the flow, we will tap into the that warmer air somewhat. Record breaking temps pushing 15-20 C possible tomorrow down in cloud-free warm sector tomorrow.

    Latest NAM and RGEM have significantly toned down QPF for the Thursday system. NAM in particular shows a more progressive system developing more to our NE along the baroclinic ribbon - and rapidly moving away. Given the situation, can still expect a lot of model vacillation on a solution, but hopefully we can miss the brunt of this system.

    Roller coaster ride for temperatures with arctic air coming in behind the disturbance, but rapid recovery ahead of the next system later Saturday. Looking colder again for early next week. Full extent of cooling will depend on snow cover. Without any new white stuff, arctic air will have a tendency to modify fairly quickly.

    Daniel

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  24. It's been a record dry month in Eastern Canada... they are getting dust storms in Hamilton...

    If you don't believe me check the past 24 hours at Hamilton airport (5PM).

    The Sainte-Anne-de-Bellevue on the western tip of Montreal hasn't had a 5 mm+ rain in more than a month now...

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  25. Hamilton obs from yesterday..

    CYHM 202200Z 06007KT 4SM DRDU BKN110 BKN160 05/02

    4 miles in drifting dust with a 7 knot wind? Likely an erroneous obs.. more like mist which they had been reporting.

    Watched Ken Burns documentary on the Dust Bowl on PBS Sunday and Monday. Now those were duststorms! Incredible images of "black blizzards" churning up thick masses of broiling dirt clouds over 1000 feet high charging across the southern plains at 60 mph, turning day into night, burying towns in thick coats of dust. Many deaths reported due to "dust pnuemonia" with so much dust getting into people's lungs. What an awful time that must have been for those poor folks.

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  26. Re: Thursday event

    As daniel noted, models have backed off on snow amounts over southern MB Thursday, with bulk of moisture streaming through the interlake along main baroclinic zone and jet axis (where snowfall warnings are currently in effect.)

    Still, looks like we should get perhaps a couple cm here in the RRV Thursday afternoon/evening as colder air works in, and northerly winds pick up. Most guidance going with about 1-2 cm for Winnipeg Thursday, while Euro continues to be most aggressive with about 6 cm between noon - 6 pm. Note the risk of freezing rain for us overnight, although bulk of moisture expected to the north of RRV.

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  27. NWS Grand Forks is going bullish with this event with a winter storm watch. They are following the GFS/UKMET guidance, at this point. Forecasting 3-7 inches of snow in N ND and N MN.

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  28. 3-7" seems on the high side based on what I'm seeing, but I suppose there could be issues with reduced vsbys in snow/blowing snow through the southern RRV, especially by evening.

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  29. Rob,

    Signs continue to move toward much colder air into the weekend and next week.

    Could we be looking at a prolonged stretch of colder below normal temps over next few weeks given that the AO is trending towards more negative?

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  30. +14 C in Fargo this afternoon, while we struggle around 1-2 C with clouds and NE flow. Warmer yet in SW Minnesota with readings in the low 20s common.

    Temps should hold their own thru the early part of the overnite period.. with NAM showing us actually tapping warm sector and SE flow later this evening. Initial band of forcing along mid level temp gradient should focus to our north. Any precip that does fall along southern edge of band will likely be rain (or freezing rain depending on low level inversion) as warm air aloft (> 5 C aoa 925 hPa) surges north.

    As system starts closing off and moves to our east, arctic air rushes in, and band of forcing slumps southeastwards. However band looks to weaken as it moves over us tomorrow, with most models only showing around 2 cm accumulation.

    Daniel

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  31. Latest from NWS GF....1-3 inch snow band north central ND into the central RRV into nrn MN... seems some consensus of snow band along or nr MOT-GFK-BJI area.... nothing huge. I am so ready for winter....so hard for me at least to take the mid 40s in Grand Forks today (Wed).... I swear I was born to live in Baker Lake :)

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  32. I heard a Winnipeg media source say today they could see freezing rain on the radar. Is there a radar source available which shows the phase of precip, including freezing rain?

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  33. I see TWN has radar with precip phase, including something called "Ice".

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  34. Cold front quite evident this evening stretching from Interlake into southwest MB, with temperatures falling to -5C or lower north of front. Some patchy freezing rain occurring along and ahead of front, changing to light snow behind it. That front should be pushing through Winnipeg between midnight and 3 am, with our temps falling below freezing and some snow starting to fall. Latest guidance this evening has pushed snow amounts back up for Winnipeg.. around 2-5 cm Thursday with some gusty north winds. Right now, doesn't look like too much snow upstream in southern MB, although a good area of snow over southern SK moving east, so we'll have to see how things develop overnight as colder air deepens. Whatever the case, a colder and blustery day tomorrow compared to what we've been experiencing this week.

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  35. Hey Rob,

    Thoughts on the 5-10 cm on Saturday WN is forcasting?
    Could it be more?

    thanks!!

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  36. Re: Saturday system

    Models indicating a clipper type system moving across southern MB with snow spreading in by morning and ending by evening. Looks like better chance for heavier snow will be across Interlake closer and north of main low. 5-10 cm seems a bit high for Winnipeg.. most models are in the 1-5 cm range. We'll be in a southerly flow ahead of the system with a band of snow coming across.. typically, we don't see a lot from these setups unless the low tracks further south... but there could be a few hours of snow and blowing snow in the RRV if those southerly winds are strong enough.

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  37. Depending on how cold it gets for the rest of November, this could potentially be the first colder than normal November since 2003. I'm not liking those minus double digit highs. Yuckkk

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  38. Hi Rob,

    I see EC has upped the amounts today to 5-10 cm now yet WN is only calling for 1-3 cm. Which forecast do you think is right?

    thanks

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