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> Eastern Canada Winter Storm February 5-7, Medium Range Potential
Torontoweather
post Jan 30 2017, 01:07 PM
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Well, this storm potential has been talked about a few times in the winter thread and clipper thread, so I figured I'd get the discussion started. First of all, a warning of caution when looking at the models: the system does not come fully ashore until Saturday between 00z and 12z, so until then expect fairly major run-to-run variation and inconsistencies. However, we can look at ensembles to get an idea of whether there is any clustering going on as well as looking at forecast teleconnections.

Let's start with the latter:
Teleconnection Forecasts

From this image we can see that in the period leading up to storm system (which is important because three of the 4 indices shown are in the pacific so its downstream effects are not usually felt until several days after) we have a transitioning PNA from negative to positive, an increasingly negative WPO and EPO and an increasingly positive NAO. From this we can gather a few things:

1. Negative WPO and EPO generally signify more cold air available to central and eastern Canada.

2. Transition from negative to positive PNA signifies a transition to more ridging in the west and troughiness in the east

3. A positive NAO signifies a strengthening SE ridge.

Overall, these ingredients combined together certainly mean that a storm system, and potentially a potent one, is possible in the Great Lakes and/or eastern Canada/US. However, the devil's in the details of course, in terms of how these pieces come together in terms of storm formation and track.

This leads into the following images, some snapshots of ensemble forecasts:

Here is this morning's 00z ensemble forecast at hour 168:


What we should notice from each one of these individual ensemble members are either two area of lower pressure: one in northern Ontario and the other in the south-central or SE US, or one area of low pressure in and around the Great Lakes. This outlines well the issue that we seem to be dealing with: a phasing or lack thereof of a northern stream low pressure and a southern stream low pressure. Whether or not these phase and how amplified the trough can become will determine the strength and track of the storm(s).

For comparison sake, here's a look at the 00z Canadian ensembles at the same hour:


And the ECMWF Ensemble mean and spread, as well as the operational ECMWF on the right:


From these forecast charts, we can see that as of right now, there seem to be more individual ensemble members leaning towards an unphased solution, with the northern stream being the dominant one and essentially acting as another clipper-type system.

It's tough to say exactly what we'll happen but either way, precipitation is likely in this period in Eastern Canada; type and amounts to be determined (though I would say snow is the most likely given the amount of cold air).

This post has been edited by Torontoweather: Jan 30 2017, 01:08 PM
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SNOWBOB11
post Jan 30 2017, 04:22 PM
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Great wright up Toweather. Pretty much summed up all the factors for this system. FWIW the 12z op euro had the northern stream not phasing with the energy from the south. It's still going to be a while before models have a better idea of whats going on though.
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EOsnowmom
post Jan 31 2017, 03:15 PM
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IMBY the Accuweather forecast is starting to sniff this one out, TWN not so much. There's 7cm snow forecast for the Feb 7 and an icy mix for Feb 8. Still a ways out, still fun to watch.

This is for February 8:
Attached File  __.JPG ( 67.87K ) Number of downloads: 0
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Ottawa blizzard
post Jan 31 2017, 08:28 PM
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Unfortunately this is looking like a rain maker for southern Ontario. Things could change, of course. One has to wonder if the very warm Great Lakes are playing a big role in preventing cold air from holding on long enough to allow for a straight snowstorm.
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travis3000
post Jan 31 2017, 08:43 PM
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We should maybe change this to Feb 7-8th? I think the 5th might be too early no?

But yeah, todays models agree on a big rain maker for Southern Ontario. I am not too keen to jump on that bandwagon though just yet. There will be plenty of cold air in place in front of this storm. My guess is that the areas N and NW of Toronto right through Eastern Ontario and into Southern Quebec are at risk for some frozen precip (freezing rain, sleet, snow). Models in my opinion will trend towards a weaker storm, with more cold air sticking around. SW Ontario and near the lower lakes might have a higher chance of rain, but the interior of Southern Ontario eastwards keep your eye out.

This post has been edited by travis3000: Jan 31 2017, 08:44 PM


--------------------
Alliston,ON 2016/2017 Snowfall:

October: 1.5cm
November: 7cm
December: 70cm
January: 20cm
February: 27.5cm
March: 9cm
April: 13cm
TOTAL: 148cm
--
2015/2016 Total: 121cm
2014/2015 Total: 113.5cm
AVERAGE Annual Snowfall: 155cm

Travis
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Lake effect
post Feb 1 2017, 07:24 AM
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Definitely looking like 7-8th, so probably best change the thread title. For me this is the make or break storm of the season. Coming in the middle of spell of sustained cold, if it is like the 00z GFS, then 2016/17 will be a passable winter, but if it is like the 06z, then it will push things way over the edge into it being a *bleep* of a winter:

00Z

Attached File  gfs_mslp_pcpn_frzn_us_28.png ( 181.17K ) Number of downloads: 1


06Z

Attached File  gfs_mslp_pcpn_frzn_us_27__1_.png ( 195.3K ) Number of downloads: 1


This post has been edited by Lake effect: Feb 1 2017, 07:26 AM
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Torontoweather
post Feb 1 2017, 07:27 AM
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QUOTE(Lake effect @ Feb 1 2017, 07:24 AM) *
Definitely looking like 7-8th, so probably best change the thread title. For me this is the make or break storm of the season. Coming in the middle of spell of sustained cold, if it is like the 00z GFS, then 2016/17 will be a passable winter, but if it is like the 06z, then it will push things way over the edge into it being a *bleep* of a winter:

00Z

Attached File  gfs_mslp_pcpn_frzn_us_28.png ( 181.17K ) Number of downloads: 1


06Z

Attached File  gfs_mslp_pcpn_frzn_us_27__1_.png ( 195.3K ) Number of downloads: 1


There's a system before this one on the 5th.
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Lake effect
post Feb 1 2017, 07:47 AM
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OK, just following on from what Travis said, I will start a new thread. As an aside, the bleepometer is very sensitive on this forum, words that aren't even considered remotely naughty elsewhere get bleeped out. Very odd.

This post has been edited by Lake effect: Feb 1 2017, 07:55 AM
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Torontoweather
post Feb 1 2017, 07:49 AM
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This thread concerns the following system:

http://www.pivotalweather.com/model.php?m=...conus&dpdt=

http://www.pivotalweather.com/model.php?m=...conus&dpdt=

At this point it looks like it will have a bigger impact from Quebec eastwards but that could still change due to the highly uncertain pattern we're entering.
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Torontoweather
post Feb 1 2017, 07:50 AM
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QUOTE(Lake effect @ Feb 1 2017, 07:47 AM) *
OK, just following on from what Travis said, I will start a new thread. As an aside, the bleepomter is very sensitive on this forum, words that aren't even considered remotely naughty elsewhere get bleeped out. Very odd.


Sounds good! Haha yeah noticed that as well tongue.gif
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Torontoweather
post Feb 1 2017, 12:49 PM
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Starting to look a little better on the 12z GFS and 12z GDPS (CMC):

Total snowfall on the 12z GFS:


Total snowfall on the 12z GDPS:


Tough to say where this goes from here, but I think this has the potential to be a 5-15cm event, particularly from eastern Ontario through Quebec and into the Maritimes and Newfoundland.
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snowgeek93
post Feb 2 2017, 09:28 AM
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This clipper barely looks like anything for here unfortunately.


--------------------
Thornhill, Ontario Snowfall (Buttonville Airport):

2016/2017: 142.6cm (Weak La Nina)
2015/2016: 96.4cm (Strong El Nino)
2014/2015: 118.7cm (Weak El Nino)
2013/2014: 184.8cm (Neutral)
2012/2013: 151.6cm (Neutral)
2011/2012: 99.9cm (Weak La Nina)
2010/2011: 168.1cm (Moderate La Nina)
2009/2010: 71.3cm (Moderate El Nino)
2008/2009: 253cm (Weak La Nina)
2007/2008: 251.6cm (Moderate La Nina)

Average Snowfall (Buttonville Airport): 142.6cm

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Lake effect
post Feb 4 2017, 03:50 PM
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Quite a nice bit of LES on the back of this, maybe a 5-15cm shot for areas south east of Georgian Bay and off Huron around Goderich, and northward. Winds pretty good for Barrie.

Attached File  hwn_36.gif ( 33.35K ) Number of downloads: 0


Attached File  nam4km_ref_frzn_neus_33.png ( 178.75K ) Number of downloads: 0
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snowgeek93
post Feb 4 2017, 04:03 PM
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Hope you guys in Barrie retain your snowpack. Heading up there sometime in the next little while and would hate for it to be the one time where there's not much snow up there.


--------------------
Thornhill, Ontario Snowfall (Buttonville Airport):

2016/2017: 142.6cm (Weak La Nina)
2015/2016: 96.4cm (Strong El Nino)
2014/2015: 118.7cm (Weak El Nino)
2013/2014: 184.8cm (Neutral)
2012/2013: 151.6cm (Neutral)
2011/2012: 99.9cm (Weak La Nina)
2010/2011: 168.1cm (Moderate La Nina)
2009/2010: 71.3cm (Moderate El Nino)
2008/2009: 253cm (Weak La Nina)
2007/2008: 251.6cm (Moderate La Nina)

Average Snowfall (Buttonville Airport): 142.6cm

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Lake effect
post Feb 4 2017, 09:13 PM
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QUOTE(snowgeek93 @ Feb 4 2017, 04:03 PM) *
Hope you guys in Barrie retain your snowpack. Heading up there sometime in the next little while and would hate for it to be the one time where there's not much snow up there.


If we get a good 10 cms tomorrow, should be fine. Have over 20 cms of compacted snow, should be some LES on the backend of the ugly mess coming through tuesday as well.
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snowgeek93
post Feb 5 2017, 09:24 AM
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FWIW, there's some light snow falling now from this clipper.


--------------------
Thornhill, Ontario Snowfall (Buttonville Airport):

2016/2017: 142.6cm (Weak La Nina)
2015/2016: 96.4cm (Strong El Nino)
2014/2015: 118.7cm (Weak El Nino)
2013/2014: 184.8cm (Neutral)
2012/2013: 151.6cm (Neutral)
2011/2012: 99.9cm (Weak La Nina)
2010/2011: 168.1cm (Moderate La Nina)
2009/2010: 71.3cm (Moderate El Nino)
2008/2009: 253cm (Weak La Nina)
2007/2008: 251.6cm (Moderate La Nina)

Average Snowfall (Buttonville Airport): 142.6cm

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travis3000
post Feb 5 2017, 10:45 AM
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We got nothing from this clipper like expected, areas east of GB got hit hard though with Parry Sound up through North Bay picking up 15cm!


--------------------
Alliston,ON 2016/2017 Snowfall:

October: 1.5cm
November: 7cm
December: 70cm
January: 20cm
February: 27.5cm
March: 9cm
April: 13cm
TOTAL: 148cm
--
2015/2016 Total: 121cm
2014/2015 Total: 113.5cm
AVERAGE Annual Snowfall: 155cm

Travis
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snowbelt
post Feb 5 2017, 11:10 AM
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Light dusting here this morning (1cm) Looking like another wave of snow building off of G Bay at the moment heading south .
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Lake effect
post Feb 5 2017, 01:39 PM
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QUOTE(travis3000 @ Feb 5 2017, 10:45 AM) *
We got nothing from this clipper like expected, areas east of GB got hit hard though with Parry Sound up through North Bay picking up 15cm!


And they are still getting hit. Had about a cm here. Been so close, but these ones often don't yield much for us due to the escarpment effect. Looking forward to later...feeling lucky, think we will get closer to 10 cms.
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snowgeek93
post Feb 5 2017, 01:44 PM
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Just a brief period of snowfall this morning. Looked nice!


--------------------
Thornhill, Ontario Snowfall (Buttonville Airport):

2016/2017: 142.6cm (Weak La Nina)
2015/2016: 96.4cm (Strong El Nino)
2014/2015: 118.7cm (Weak El Nino)
2013/2014: 184.8cm (Neutral)
2012/2013: 151.6cm (Neutral)
2011/2012: 99.9cm (Weak La Nina)
2010/2011: 168.1cm (Moderate La Nina)
2009/2010: 71.3cm (Moderate El Nino)
2008/2009: 253cm (Weak La Nina)
2007/2008: 251.6cm (Moderate La Nina)

Average Snowfall (Buttonville Airport): 142.6cm

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