 |
NAM prog valid 9 am Monday Dec 3rd.
Storm system tracking across Manitoba
will bring swath of snow to central
regions, and rain to the south before
colder air sweeps in. |
A fast moving jet stream across southern Canada will be resulting in a variable weather pattern this week over southern Manitoba, with frequent swings in temperatures as weather systems sweep across the Prairies. In the short term, a storm system over northern Montana this afternoon will track into the Manitoba interlake regions overnight into Monday, bringing a swath of heavy snow across central Manitoba. Southerly winds ahead of the system will draw up milder air over southern MB, with temperature rising above freezing over the south, including Winnipeg and the RRV. As the storm system tracks into the interlake overnight into Monday morning, some rain is likely over the south while a band of freezing rain is possible over the western Parklands and southern interlake regions. Monday will start off mild and wet over the RRV, however a cold front from the storm system to the north will sweep across the RRV, bringing a return to colder temperatures. In Winnipeg, temperatures near +1C at 9 am are expected to fall to -5C by 3 pm, along with gusty NW winds and a chance of flurries. Colder but seasonal temperatures are forecast for Tuesday before another warmup by Wednesday. Long range models are forecasting a potential for some snow by next weekend with colder temperatures to follow in its wake.
Radar notes: Note that radar images from the
Weatheroffice website are now on SNOW rate and will overdo precipitation intensities during rainfall events. Consult
Brad's radar viewer from
A Weather Moment for radar images showing more accurate RAIN rate intensities during rain or freezing rain events in the winter (select 1.5 km CAPPI for RAIN rate) Weatheroffice radar images are fixed on snow rate across the country until spring.
Rob,
ReplyDeleteDoes the snow potential for next weekend look like anything significant in terms of a possible major storm?
Too early to say how significant it may be at this point. Right now, models are indicating snow amounts in the 5 cm range for Winnipeg as the main system tracks through the central Plain states. However GFS is hinting at some heavier amounts of 10 cm or more possible over southern MB. Something to keep an eye on as the week progresses..
ReplyDeleteSnow depths should take another beating overnite and early tomorrow. Once again bare patches are already starting to show up in open country. Temperatures will likely hold steady or rise slightly with moderate winds and upstream dewpoints at +3-4 C. The fog and any drizzle should help really eat away at the snowpack. Watch for a good burst of mixing tomorrow morning as winds turn SW and tap 925 hPa temps near 5 C. By mid afternoon cold core starts approaching (NAM), while Canadian guidance (especially SCRIBE) is faster with cold advection and drops ours temps sooner. Looks like N Dakota - especially south of Grand Forks will bask in another balmy day as the cold core only slowly oozes south across the border.
ReplyDeleteThe 49th parallel has been a real dividing line so far this cold season, with lots of above normal incursions over the northern plains and little snow cover. Meanwhile, bitter cold arctic air has been bottled over the northern Prairies and NWT, with a deep snowpack over the southern Prairies. That is a fairly typical La Nina pattern, but perhaps with the baroclinic zone a bit further north than usual.
Daniel
Btw.. NAM just clips us with some showers forming between the back edge of elevated warm advection zone (700 hPa) and trough. Should be thru by 7 am. Cannot rule out 3-5 mm of plain old rain - especially for SE Manitoba. Main synoptic precip band and mid level frontogenesis sets up well to our north over central Manitoba.
ReplyDeleteAnd yeah, that system looks interesting for next weekend. Complicated set up with a double barreled system. Main low over the central/southern Plains and inverted trough up thru Manitoba. Typically, energy consolidates around the main Colorado low, and precip associated with the inverted trough weakens. Meanwhile brutally cold arctic air pools over N and C Alberta - again typical of a La Nina type pattern.
Daniel
Daniel, could we be in store for some decent snowfall next weekend here in Winnipeg and the RRV or just some minor accumulations?
ReplyDeleteAnd are we also likely to get a taste of some of that brutally cold air once next weekend's system passes us?
Winnipeg may get rain in December for the first time since 2004.
ReplyDeleteRe Anonymous..
ReplyDeleteHard to stay this far out. I can practically guarantee that there will be a lot of vacillation from the models given the complicated set-up and transfer of energy. As far as the cold afterwards.. it depends on any new snow cover. If all we have is a degraded 2-5 cm with bare spots out in the open.. the airmass will modify rapidly as it moves east. Overnite Saturday into Sunday could be brutally cold for Edmonton. Coldest period for us looks to be Monday overnite to Tuesday at this point.
Re Tonite..
I see a lot of weather stations including the airport have risen above freezing tonite. Temperatures at Grand Forks and Hallock continue rising.. which is a good sign.
Daniel
Area of rain over RRV and SE MB spreading north this morning.. with light rain just pushing into Winnipeg as of 7 am. 1 or 2 mm possible through 9 am. Temperatures will be falling towards the freezing mark by 9 or 10 am, although bulk of rain should be through by then. Note however that there is some freezing rain on the west side of this rain band where temperatures have dropped to the freezing mark or lower west of the city (currently freezing rain and -1C in Portage). We will continue to drop below freezing through late morning into the afternoon as west to NW winds increase, with temperatures down to -2C in Winnipeg by late morning, and -5C by mid afternoon.
ReplyDelete9am Monday - my driveway is a skating rink!
ReplyDeleteChris in Westwood.
Rain was coming down pretty good out there this morning, even looked like some big convective raindrops at times. Some good ponding of water on area roadways especially where storm drains are clogged. Back edge of rain just pulling into the west end of the city, should be ending across the city within the hour just as temperatures are reaching the freezing mark and lower.
ReplyDeleteWith subfreezing temps coming in, things will freeze up this afternoon into this evening. Main roads should be OK due to salting, however side roads and sidewalks will likely ice up as the afternoon progresses. Keep that in mind with any standing water that you see lying around..
2 mm of rain this morning at my place (Rob's Obs station overreporting precip today due to residual snowmelt) Sidewalks quite slippery, and will only get worse as temps drop this afternoon. Temperature currently right at the freezing mark.
ReplyDeleteyeah that sure was some impressive rainfall this morning for this time of the year.
ReplyDeleteif it would have been colder aloft we might have picked a quick 5 to 10CM of heavy wet snow but not looking forward to the very slippery conditions late today as temps fall.
Rob, is snowfall for the weekend still in the picture?
It's still pretty much fall in Eastern Canada...
ReplyDeleteWindsor went up to 13.4C yesterday which was the warmest spot in Canada.
Dewpoint was up 13C so it's pretty humid as well.
ReplyDeleteYes, snow event still looks possible for weekend.. although still a lot of varying opinions on evolution of system. GFS now slows it down to a Sunday/Sunday night event.. while GEM is a little more aggressive today than yesterday, bringing some snow in on Saturday. Still too much uncertainty to say how it will transpire.. just that the potential is there for some accumulating snow this weekend.
ReplyDeleteWe may see a quick shot of snow Thursday as well with a stronger cold front pushing through, but doesn't look like much at this point.
Rob, could we be looking at some very cold temps as in -30C behind that system this weekend or will the pool of cold air moderate by the time it's gets here?
ReplyDeleteJohn Sauder just said snow pellets are like freezing rain, but has gone through a thicker layer of cold air so freezes before reaching the ground. Isn't that ice pellets?
ReplyDeleteThings have gotten a lot worse past 20 minutes... snow and blowing snow with decreasing visibility, and icing up quickly with rapidly falling temps and strong winds. Careful out there... it's a nasty drive home...
ReplyDelete
ReplyDeleteAnalysis from EC continues to overestimate snow-depth for our area, with sensor data still showing an implausible 15 cm at YWG. I see ROB measured 13 cm yesterday (at a protected site), and I'm sure readings went down another cm or two with the rain and above freezing temps overnite. About 2-4 cm in the open areas at the south end of the city I would estimate, while the snow cover analyses puts us in the 10-25 cm contour. Its been said before, but it is mind-boggling that accurate and high resolution data for snow-depth are not a priority here. The point at U of M (where there is already a weather station) or Glenlea research station would be good areas to give snow-depths for south Winnipeg. Don't expect our models to be very accurate.. if we don't input correct data related to the basic physical parameters governing our radiative budget.
***************************************************
I see that EC has still not updated the links on their map at the National Climate Data and Information Archive site. You are taken to the pre-NavCanada information, which is blank for the last couple of months in some cases (since the change-over). Not sure if this has been mentioned on here, but I recall several people mentioning data missing for some locations across the country. In the case of Edmonton for example, the old reference was 'Edmonton Intl', with the new data found under 'Edmonton'. Quite silly considering the data is still from the airport out there. "Edmonton Intl B or NavCan" would seem to make more sense... or even just keeping the same station name.
Daniel
Goodness already 45 cm of snowfall in Norway House with another 10 to 20 cm tonight. Mafeking got 20 cm today (the town that had 65 cm Nov 9 to 11). Sure turning into a brutal winter in central Manitoba.
ReplyDeleteWould have been a good day for a flash freeze warning or a type of warning of that sort. Today was not something we see every December...
ReplyDeleteI could have sworn I saw clear skys for this evening in the morning forecast.
ReplyDeleteAnonymous (8:06) post:
ReplyDeleteYou did not imagine that clearing skies for this evening....i saw that as well.
So much for that
Meanwhile...
ReplyDeleteChicago just broke its all-time December high...
72F(22.2C) recorded today while the old record was 71F(21.7C) (December 2, 1982 and December 3, 1970)
Kansas City tied its all-time December high at 74F(23.3C).
Over here on the North Perimeter near #8 the wind gusts are huge. I think a lot higher than the Airport reporting winds of 41kmh. I would say closer to 70kmh if not higher
ReplyDeleteLooking at the SpotWX charts, the NAM seems to want to put tomorrow's freezing rain event in time for the afternoon/evening rush hour, while the GFS is a touch slower, putting the event more towards 7 and 8 PM.
ReplyDeleteRob,
ReplyDeletewhat's the latest on tomorrow's freezing rain event and this coming weekend's possible winter storm event?
Wow...60-90 cm of snow in Norway House and Gods Lake Narrows according to the SWS EC issued earlier this morning.
ReplyDeleteBand of showers progged to move across Winnipeg/RRV tomorrow afternoon between 3 and 6 pm with temperatures still slightly below freezing.. hence a freezing rain threat around late afternoon rush hour. Doesn't look like a lot of rain.. perhaps 1 mm or so.. so it's not a major band, but may be enough to slick up untreated surfaces. Main roadways in the city should be fine since temperatures will be mild enough for salt to keep main roads wet.. Gusty south winds to 50 or 60 km/h will accompany the "warmup" but it won't feel all that pleasant.
ReplyDeleteSnow threat for weekend looking like less of an impact for us.. perhaps a few cm Saturday, but main storm system will be tracking well to our south and east.
Southern Ontario getting some of that Chicago heat today.. up to 18C over the Niagara region and Ottawa valley today, 19C in Brockville. That'll be it though as cold front comes through today and tonight, with near or subfreezing temps tomorrow.
ReplyDeleteHow can a little community have such a big difference in snowfall amounts from one end to the other? I'm talking about Norway House. I'm guessing 60-90 cm is a wild guestimate versus actual measurements?
ReplyDeleteAnd how does EC come up with those amounts? 60-90 cm is a huge gap of uncertainty
ReplyDeleteAnonymous.. EC phoned around and got several reports in that 2-3 foot range in Norway House.. but yes, I suspect that those reports were just best estimates based on the heavy drifting that accompanied the heavy snow. But basically, reports indicated snow depths knee to waist high, with 2 metre drifts.. so it was a substantial amount. Unfortunately, nothing will ever be officially entered in the climate archives because there are no official snowfall observations for Norway House.
ReplyDeleteBy the way, another 10 cm+ on the way for them tomorrow.. :)
Those southerly winds tomorrow could be pretty strong in the afternoon, with a 50kt low level jet progged over the RRV by mid afternoon. Low level inversion will likely keep those strongest winds from mixing down, but gusts of 60-70 km/h possible for Winnipeg tomorrow afternoon. That will certainly add a bite to any warming we see tomorrow..
ReplyDeleteThanks Rob
ReplyDeleteToo bad no data is entered officially then.. considering this is turning out to be an incredible winter for snowfall so far in central Manitoba.
Rob,
ReplyDeleteI've been hearing of the possibility of some very frigid air from the yukon territory sinking southward down into our region next week or shortly after.
certainly the ECMWF long range is also indicating that, what are your thoughts on that?
Visible satellite from today shows trace to 2cm of snow south and east of a Gretna to Morris to Ste Anne line. As soon as winds switch around to SE tonite, temperatures will not go anywhere as we tap flow off of that bare ground. Some guidance - especially higher resolution RGEM and RAP are showing temperatures cratering early tonite into the minus -20's. Again, they are likely picking up on overestimated snow-depths for our area, and I would lean more towards warmer guidance like GFS and NAM.
ReplyDeleteAll guidance including meteocode, show temperatures increasing after midnight, but due to programming glitch or whatever, public forecast makes no mention of it. These southerly and southeasterly flows have proven quite balmy for us, so hopefully temperatures will get above freezing early tomorrow evening before dropped back below zero after midnight.
As anticipated, models really struggling with variable pattern. Main low looks to track well off to our SE this weekend as mentioned, but they don't know what to make of an inverted trough type feature or follow-up disturbance. Latest Canadian guidance (GGEM) giving us 8-9 cm of snow Saturday.
As long as the northern plains and upper midwest stay free of snow-cover, deep arctic air will have a time making any head way south of the int'l border, and we'll be in line for occasional bursts of warm southerly flows.. looks like an interesting and active period the next while.
Daniel
As Daniel noted.. a good setup for abnormal temperature trend tonight for Winnipeg as our winds shift to the southeast and increase overnight, along with area of hi cloud to our west that will be spreading in here. Lows of -18C or so this evening likely rising towards the -10C mark by morning.
ReplyDeleteWinds have turned to SE at YWG.. that should do it for overnite lows there. Got as cold as -17 C with the adjacent weatherbugs in NW Winnipeg around -15 C. Narrow ribbon of cold surface temperatures over western RRV and southern interlake. Probably an area of thin low clouds from northern RRV towards the Whiteshell keeping temps considerably warmer off to the NE. At the same time higher based clouds moving in from the west as Rob mentioned..
ReplyDeleteDaniel
Daniel,
ReplyDeleteAre temps likely to rise here in Winnipeg tonight and what's the latest on tomorrow's freezing rain event?
I've noticed ECMWF long range model is showing frigid air for us mid to late december, what are your thoughts on that?
Yes temperatures will rise overnite.. as for the long range, I have only looked at GFS, which shows a variable pattern and potential for a very steep temperature gradient between the Prairies and northern Plains. As I mentioned, without snowcover to our south, we will remain closer to the warmer air and be able to tap some nice southerly flows. Potential is there for systems to move up in a SW flow over the midwest and Great Lakes so we'll see what happens..
ReplyDeleteDaniel
Daniel,
ReplyDeleteAre we expecting a prolonged period of freezing rain with tomorrow's event?
As Rob mentioned, it does not look like a significant band of precipitation. All guidance as of late tonite shows 1-2 mm of precipitation over several hours.
ReplyDeleteInfrared satellite loop shows squeeze play continues.. a thin area of low clouds or moisture (darker/warmer on infrared) is retrograding west, while high clouds move east. Coldest temps over the deeper snowpack of the western RRV up through Woodlands, but temperatures everywhere will start rising in earnest after midnight.
Daniel
After Kansas City and Chicago, it was Ottawa's turn to break an all-time December high...
ReplyDeleteThey were 17.9C while the old all-time record was 16.3C from 1998.
The Canadian warmspot was Brockville still in Eastern Ontario at 19.5C.
Freezing rain a risk this afternoon/evening over Winnipeg and RRV although not a given with several factors to consider as the FO45 discussion mentions. While it will certainly be warm enough aloft for a freezing rain risk this afternoon, models are pretty dry on the development of rain band ahead of surface trof coming through Winnipeg, with a slightly better chance of development to our north and east this evening. In addition, progged soundings indicate that we may have a cold enough layer in the low levels to give more of an ice pellet threat than freezing rain. Whatever the case, the risk of freezing rain is there, but I don't think it's a definite and we'll have to keep an eye on radar to see progression of any precip development.
ReplyDeleteMorning aircraft AMDAR soundings out of Winnipeg already showing southerly winds of 40 kt at 950 mb (1500 ft ASL), and 45 kt at 925 mb (2500 ft ASL). Could be seeing 70 km/h gusts by early afternoon as low level jet increases even further (50-55 kt)through midday.
ReplyDeleteRob, can we expect this up and down cycle with the temperatures to continue next week and even beyond as well?
ReplyDeleteAlso, are there any hints of possible major snowfall down the road let's say between now and christmas day given the seemingly active pattern we are in right now?
Note that EC has just issued a Freezing Rain Warning for pretty much all of Southern MB including Winnipeg.
ReplyDeleteCould be be a very slippery drive home later during rush hour.
I see Woodlands radar is down again...hopefully not something significant especially with the freezing rain later today
ReplyDeleteI think its actully the foxwarren radar thats down. Brandon area
ReplyDeleteNo I stand corrected it is woodlands
ReplyDeleteGood news for those who want to track that band of freezing rain later today.....Woodlands radar is working again.
ReplyDeleteWoodlands was taken down for some routine maintenance this morning, but it's back up and running now.
ReplyDeleteSome echoes showing up around Estevan SK but still very light.. pretty dry in the low levels with Estevan reporting some virga. Note that radar rates on SNOW rate will overdo rainfall echoes, so it's better to look at 1.5 km cappi (rain rate) for a more accurate assessment of liquid precipitation intensity.
Hey,
ReplyDeleteDo you still think we will get the freezing rain?
thanks
Still a risk of freezing rain for us.. can't say it WON'T happen, but it doesn't look like much at this point. If we see anything, it'll likely be sometime early this evening but even then, amounts should be light and duration shouldn't be that long unless this area intensifies suddenly. The more impressive precipitation with this system is over central SK tracking into central MB, where vsbys are down to 1/4 mile in heavy snow at times.(like in Saskatoon)
ReplyDeleteRob,
ReplyDeleteCan we expect to continue to see this up and down cycle with the temperatures of the next week or two?
Also, are there any hints of major snowfall let's say between now and christmas day given the seemingly active pattern that's in place?
Looks like we'll get into a colder than normal pattern for awhile after tomorrow, with brief recoveries to near or above normal as system track across us. At this point, no hints of any major snowstorms over the next week or so with occasional clippers affecting us, however given the proximity of the storm track, it's possible we may see something more significant before Xmas. But just to tough to say at this point given how variable the pattern is.
ReplyDeleteTemperatures already up to -1 to -2 C for all areas that have some buildings and trees to generate a bit of turbulence.. airport and other areas with more laminar flow still around -3 C. Lots of mixing in the westerly flow behind the front temps in the 3-6 C range over southern Saskatchewan. Don't be surprised if temps will possibly spike up to 2-3 C around midnight here.. in line with warmest guidance (GGEM).
ReplyDeleteAs far as precipitation, all models downplaying QPF except for GFS. RAP show band of showers moving over us around midnight, but having to overcome dry layer below 700 hPa. We'll see how things evolve this evening as trough moves east.
Daniel
Daniel,
ReplyDeletehas the freezing rain threat diminished for us here in Winnipeg and RRV?
As I mentioned, we'll have to follow trends this evening. I see that Brandon is reporting some light freezing rain, so we'll see how much precipitation actually makes it to the surface. We'll also have to watch temperatures along the trough, to see if pocket of above freezing temps holds up behind the band.
ReplyDeleteDaniel
Daniel,
ReplyDeleteLooks quite chilly from Friday forward...Does this look like a prolonged period of below normal temps?
Are we still expected some snow Saturday as well?
I already gave my opinion on the long range. Haven't looked at models for weekend snow potential today.
ReplyDeleteDaniel
Some scattered sprinkles about to move in.. not looking impressive on radar. Stronger returns north and south of the city. A few light returns back thru Brandon. Weatherbug network in city shows temps slightly above freezing for many spots. Note however that some ground surfaces likely remain below freezing..
ReplyDeleteWith continued warm advection from the snow-free areas to the south, and nice warm pocket persisting in SE Saskatchewan behind the trough, we'll likely see temps climb a few degrees above zero for all locations early overnite before cold advection sets in.
Daniel
Radar showing some weak echoes moving across the city, but so far nothing reaching the ground..at least here in SW Winnipeg. As Daniel noted, stronger echoes to our northeast towards Gimil, where light showers are likely reaching the ground as some freezing rain. Band will be east of the city shortly, so freezing rain threat for this evening will be diminishing fairly soon.
ReplyDeleteWas not much of a threat, that's for sure...nobody will complain about that though. Nasty winds tonight however.
ReplyDeleteRain band intensifying right over southern and eastern parts of the city.. hardly a drop in the west end, but a little more reaching the ground further east. Luckily, band is moving fairly quickly and should be out of the city within the next 20 minutes.
ReplyDeleteFreezing rain here in south St Vital now.. Getting really icy.
ReplyDeleteJJ
Freezing rain here in Windsor Park as well...Pretty icy in this neighbourhood right now as well
ReplyDeleteLooks like another band of Freezing Rain developing northwest of Winnipeg moving toward the city, but very narrow.
ReplyDeleteYeah, maybe that second band will catch me.. that first band pretty much missed me. Barely a few drops in Charleswood.
ReplyDeleteRaindrops in Charleswood.
ReplyDeleteIce pellets now.
ReplyDeleteIce pellets came down pretty good for a minute or two.. but that's about it. Just cloudy and windy now.
ReplyDeleteRob,
ReplyDeleteIs that pretty much it for the precip tonight for Winnipeg and could the temps actually rise above zero for a short time early tonight?
Does the snow potential for Saturday still exist?
This last band of ice pellets/light freezing rain going through right now should be east of the city by 10 pm then that should be it.. (unless another band forms that I don't see right now)
ReplyDeleteAs Daniel noted earlier, temps may pop above freezing briefly around midnight as winds shift into the WNW.. tapping some milder air that has popped temperatures up to +2 in Brandon and Portage.
Peak gust of 76 km/h at YWG airport yesterday.
ReplyDeleteModels trending further north with the Saturday system. Current trends would give 5-10 cm for a good chunk of southern Manitoba. Will be interesting to see if this continues.
ReplyDeleteRob or Daniel,
ReplyDeleteIt's looking like we will get a good shot of snow Saturday according to latest indications.
What are your thoughts on as to how much snow may fall here in Winnipeg and RRV?
Big range in guidance for tonite's low with shallow layer of high pressure building in from the NW, flow as low as 850 hPa stays fairly strong. Big range in lows for tonite in the guidance - RGEM SCRIBE gives -17 C with raw GGEM showing -28/-29 C. See that meteocode leaning on warmer guidance with -19 C..
ReplyDeleteThings looking very unclear wrt to evolution of Saturday system. NAM and the Canadian models awkwardly show a system at the surface dropping SE then turning NE and intensifying as upper trough becomes negatively tilted and starts closing off. Warm advection and then deformation zone affect us with persistent snow band. GFS on the other hand, shows energy transfecting to a low over the central and southern plains... which then ejects NE towards the lower Great Lakes. At this point, I have to say GFS scenario looks more plausible based on how these systems often develop. We'll see how trends evolve in next model runs..especially NAM which seems to have joined in more on the northern solution.
Daniel
Daniel
Daniel
Daniel,
ReplyDeleteDoes that basically mean we will not be affected by that system Saturday?
No - it means there is still considerable uncertainty regarding the evolution of the system. Models often have a really tough time with split flows, and phasing of energy or lack thereof. For that reason I wouldn't rule out the GFS solution yet. As I stated, we'll see what subsequent model runs bring..
ReplyDeleteDaniel
Daniel,
ReplyDeleteSo could we possibly be looking substantial snowfall Saturday or minor snowfall based on current indications?
Daniel,
ReplyDeleteor is it just too tough to say right now?
Models trending around 5 cm for Winnipeg Saturday with potential for up to 10 cm if narrow band of heavier snow moves over city. Main energy will be transferring to central plains low tomorrow, with secondary lobe over southern MB. As Daniel noted, models often have difficulty with these split phase systems, so we'll just have to wait to see how things develop. Gut feeling is around 5 cm for the city based on current guidance, but can't rule out higher amounts.
ReplyDeleteRob - Where do you see 5 cm? I'm seeing:
ReplyDeleteRegional GEM: 2.5 cm
Global GEM: 3.8 cm
NAM 3.5 cm
GFS: 2.1 cm
Regional SCRIBE matrices: 2.9 cm
Euro: about 4 cm
I'm just looking at the raw numeric output of course, which isn't much of an analysis.
Garth... I was assuming snow:water ratios of 15-20:1 for tomorrow. Given raw model output of 2-4 mm for Winnipeg, that would translate to about 3-8 cm.
ReplyDeleteAh, thanks Rob. Yes, I'm always assuming 10:1, because I don't yet know how to estimate the real value. Any reading you can suggest on that subject?
ReplyDeleteRob,
ReplyDeleteI see EC has downgraded it's snowfall amounts from the 5 to 10 CM earlier today to now less than 5 CM.
How much snow do you think we will get here in Winnipeg tomorrow?
All raw guidance pretty much shows between 0.5 to 3.5 cm of snow at this point as was mentioned..
ReplyDeleteModels are stronger and further south with the system tomorrow. Things looking pretty brutal for southern N Dakota and west central Minnesota with significant accumulations possible and strong northerly gradient developing behind the low. NAM and other models suggest warm advection band to move in tomorrow morning. It will have to overcome dry air from departing high initially, and we'll see how far it can persist.. can't rule out a few cm's. Deformation band gets going as upper low winds up, and may back into the far southern RRV and SE Manitoba before system starts pulling east - and disturbance hanging back in upper trough starts becoming dominant over the central plains and lower great lakes. Still wouldn't rule out some surprises if more of an inverted trough develops rather than a discrete low.
Daniel
PS
ReplyDeleteAs Rob mentioned, if snow-water ratios are higher, and the snow is fluffy, it still could translate to 2-5 cm accumulation for tomorrow.
Daniel
Daniel,
ReplyDeleteWhat does the active weather situation look like for us between now and christmas, any big storms on the horizon or is it too difficult to tell what may happen at this point?
Garth… I don't have any material on SLR at the moment but if I find some I'll let you know. SLR is a complex thing, based on surface temperatures, cloud layer temps, wind speeds, and stability considerations. Most ideal temperature range for snow crystal growth is in the -10 to -15c range, mainly through the cloud layer. Generally SLR is around 10:1 for temps just below freezing and increase to 20:1 as you get into the minus teens... but drop towards 10-15:1 or so in the minus 20s or colder as the cystals become more needle like.
ReplyDeleteSpeaking of snow, looks like area moderate to heavy snow is moving across western North Dakota and SE SK into SW MB. Looks like main area will be tracking across international border overnight into Saturday. Will see how far north area spreads.
I find it interesting yesterday EC called for 5-10cm for today then at 4pm changed it to 2-4cm. Now as of 5am they are back to 5-10cm
ReplyDeleteSnow has spread into Winnipeg/RRV this morning with heaviest concentration mainly south of the Transcanada. Snow should be intensifying over city shortly with a good 5 cm likely by mid afternoon. I'm thinking that 10 cm is probably on the high side for Winnipeg, but it's possible for some areas of the RRV especially south of the city.
ReplyDelete