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> Eastern Canada Winter Storm: March 13-16, Medium Range Forecasts
Torontoweather
post Mar 9 2017, 12:10 PM
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Well, since the US side of the forums is going nuts over this, and I've been watching it over the past few days, I figured I'd start a thread! I have to keep it brief because I have to go to class, but here's a look at the latest models:

12z CMC total snowfall:


12z GFS total snowfall:


12z UKMET:






GFS and CMC very similar while the UKMET definitely more amped and further west. Models have been all over the place, like usual, so only time will tell. I have no doubt that we'll talk only about this storm in my "Current Weather Discussion" class which I have in a few hours. I'll let you guys what we talk about and what's on the table smile.gif

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snowgeek93
post Mar 9 2017, 01:32 PM
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Thanks for starting the thread TO! Looks like a great storm for the Northeast US and into Atlantic Canada.


--------------------
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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puttin
post Mar 9 2017, 02:02 PM
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QUOTE(snowgeek93 @ Mar 9 2017, 01:32 PM) *
Thanks for starting the thread TO! Looks like a great storm for the Northeast US and into Atlantic Canada.

Looks like some action in the last graphics for us here too, no? I knew I jinxed us back in February when I kicked winters butt out my back door and welcomed the warmth.... and someone said, oh great, now we're not going to see spring until May!! Sorreeeeeee.
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snowgeek93
post Mar 9 2017, 04:35 PM
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QUOTE(puttin @ Mar 9 2017, 02:02 PM) *
Looks like some action in the last graphics for us here too, no? I knew I jinxed us back in February when I kicked winters butt out my back door and welcomed the warmth.... and someone said, oh great, now we're not going to see spring until May!! Sorreeeeeee.

laugh.gif

You should know better by now that winter almost never ends quickly around here tongue.gif


--------------------
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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Torontoweather
post Mar 9 2017, 05:00 PM
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Alrighty, so just got back from class which we extended a half an hour today to go into more depths about this storm! There were a few main things that we discussed:

1. The difficulty that forecast models are still having as a result of the massive ridge over Alaska.

2. The development of a mesoscale-type surface cyclone just offshore of the mid-Atlantic.

Issue 1.
As a result of the essential Rex/Omega Block over the NE Pacific, the flow is being diverted into either the arctic or the subtropical/extratropical Pacific.


Part of the arctic flow eventually makes its way back SWward from western Alaska, but another part of it does not make its way back SSWward until the Northwest Territories of Canada. Not only are these regions poorly sampled, but blocking regimes are always difficult to predict; when will the energies from the Pacific and the Arctic eject? When/do they meet and phase? These are all very difficult questions to answer, and although some consistency in the deterministic models has established itself over the past 12-24 hours, the ensemble spread is still quite large in some cases.

Here's a look at the individual CMC ensemble members upper-level (500-hPa) forecast for Hour 108:
http://weather.gc.ca/ensemble/charts_e.htm...=12&Type=gz

Definitely a lot of discrepancies there.

And we can still see a pretty large spread in the ECMWF Ensembles as well:


And the GEFS:


So, again, exercise caution over the next few days as the upper-level pattern will not likely resolve itself until better sampling occurs, which will not be until Saturday or Sunday.

Issue 2.
We talked about the development or enhancement of the coastal feature as a result of mroe mesoscale-type dynamics as opposed to synoptic scale dynamics. From the following image from the 12z GFS we can see a nice cold air damming signature to the east of the appalachians, and a subsequent dip in the extension of the high pressure system.



What this dip in the isobars allows is the development of cyclonic vorticity advection along coastal regions, and in particular near the outer banks of North Carolina. As a result, we start to see the development/enhancement of a low pressure system right around that area


However, where this coastal development goes from there is highly dependent on Issue 1. What is the strength and orientation of our upper-level trough and what is the timing of phasing if and when it occurs.

Overall, despite the consistency seen among the 12z deterministic, and to a certain extent even some of the ensembles, there still remains a high degree of uncertainty with this forecast. With the being said, we came to the conclusion that a coastal development does seem to be the most probable scenario (as opposed to an upper-level low that closes off much earlier and further west as a few individual members suggest) and that a track somewhere between NE and NNW from the outer banks is the most probable.

Feel free to ask any questions or post any comments smile.gif

Thanks for reading!

This post has been edited by Torontoweather: Mar 9 2017, 05:04 PM
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plowguy
post Mar 9 2017, 05:28 PM
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Thanks for the reading Torontoweather. Way way above my paygrade! But you did break it down, and for that I'm thankful. It will interesting to see how it unfolds.
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Torontoweather
post Mar 9 2017, 05:36 PM
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Latest 18z GFS ohmy.gif blink.gif



That would be epic! Hahaha, we'll see what it looks like 3 days from now rolleyes.gif
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Jeremy404
post Mar 9 2017, 05:47 PM
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Pretty much all winter long we had storms going too north, and now this more than golden opportunity has been suppressed way south.
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snowgeek93
post Mar 9 2017, 05:52 PM
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Great looking storm for Montreal/Atlantic Canada! ohmy.gif


--------------------
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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snowgeek93
post Mar 9 2017, 05:54 PM
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QUOTE(Jeremy404 @ Mar 9 2017, 05:47 PM) *
Pretty much all winter long we had storms going too north, and now this more than golden opportunity has been suppressed way south.

We still had a couple of good ones hit us though and we always have the December period to remember rolleyes.gif


--------------------
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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MrMusic
post Mar 9 2017, 06:16 PM
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QUOTE(Torontoweather @ Mar 9 2017, 05:00 PM) *
Alrighty, so just got back from class which we extended a half an hour today to go into more depths about this storm! There were a few main things that we discussed:

1. The difficulty that forecast models are still having as a result of the massive ridge over Alaska.

2. The development of a mesoscale-type surface cyclone just offshore of the mid-Atlantic.

Issue 1.
As a result of the essential Rex/Omega Block over the NE Pacific, the flow is being diverted into either the arctic or the subtropical/extratropical Pacific.


Part of the arctic flow eventually makes its way back SWward from western Alaska, but another part of it does not make its way back SSWward until the Northwest Territories of Canada. Not only are these regions poorly sampled, but blocking regimes are always difficult to predict; when will the energies from the Pacific and the Arctic eject? When/do they meet and phase? These are all very difficult questions to answer, and although some consistency in the deterministic models has established itself over the past 12-24 hours, the ensemble spread is still quite large in some cases.

Here's a look at the individual CMC ensemble members upper-level (500-hPa) forecast for Hour 108:
http://weather.gc.ca/ensemble/charts_e.htm...=12&Type=gz

Definitely a lot of discrepancies there.

And we can still see a pretty large spread in the ECMWF Ensembles as well:


And the GEFS:


So, again, exercise caution over the next few days as the upper-level pattern will not likely resolve itself until better sampling occurs, which will not be until Saturday or Sunday.

Issue 2.
We talked about the development or enhancement of the coastal feature as a result of mroe mesoscale-type dynamics as opposed to synoptic scale dynamics. From the following image from the 12z GFS we can see a nice cold air damming signature to the east of the appalachians, and a subsequent dip in the extension of the high pressure system.



What this dip in the isobars allows is the development of cyclonic vorticity advection along coastal regions, and in particular near the outer banks of North Carolina. As a result, we start to see the development/enhancement of a low pressure system right around that area


However, where this coastal development goes from there is highly dependent on Issue 1. What is the strength and orientation of our upper-level trough and what is the timing of phasing if and when it occurs.

Overall, despite the consistency seen among the 12z deterministic, and to a certain extent even some of the ensembles, there still remains a high degree of uncertainty with this forecast. With the being said, we came to the conclusion that a coastal development does seem to be the most probable scenario (as opposed to an upper-level low that closes off much earlier and further west as a few individual members suggest) and that a track somewhere between NE and NNW from the outer banks is the most probable.

Feel free to ask any questions or post any comments smile.gif

Thanks for reading!



Great info!! Thx for writing this up.
I'm trying to not get excited at the prospects of Lake Effect here in Hamilton, but that set-up is so classic. Cold high to the north, big storm to the south, ENE wind flow, warm lake water etc..... if ever it was going to happen, it would be here.

Still lots of time for these storms to phase a bit further NW and affect us here on this forum. Could the first legit storm of the season be in mid-March?? Crazy


--------------------
Winter 2016-2017

Dec 2016: 30cm
Jan 2017: 5cm
Feb 2017: 7cm
March 2017: 35cm!! Finally!

Days with snow on the ground: 25
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MrMusic
post Mar 9 2017, 06:27 PM
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Quick illustration using the recent GFS as to why I believe West End of Lake Ontario would need to keep an eye out IF this sort of storm/track were to verify.

Cold surface temps and ENE wind flow over the wide open lake:




At 850mb the wind flow is also ENE, good alignment. The critical 850mb temp is -16 degrees over Hamilton at this time period (these maps are 8am Tuesday. Yes, I know I'm getting way ahead of myself here. It's been a ROUGH winter.)
Lake temp of about 4-5 degrees gives us roughly a 20 degree temp difference. More than adequate.




Even this far out the GFS seems to hint at the idea of a snow band at this end of the lake:



Moisture content is a close call according to the GEM for the same time period. Shows a nice 61% in Hamilton, but only 24% as close as Toronto. That dry air to the NE could hamper things.




At any rate, way too early to expect anything, but I'll keep an eye on the potential.
Any input from a lake snow expert like Travis or Cory would be more than welcomed!

This post has been edited by MrMusic: Mar 9 2017, 06:29 PM


--------------------
Winter 2016-2017

Dec 2016: 30cm
Jan 2017: 5cm
Feb 2017: 7cm
March 2017: 35cm!! Finally!

Days with snow on the ground: 25
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travis3000
post Mar 9 2017, 06:58 PM
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MrMusic the ingredients are there if this scenario plays itself out. We are still many days away so things can change. But from todays GFS runs, the Burlington to Hamilton area could see accumulating snow off Lake Ontario for the first time this winter.

Keep your fingers crossed!


--------------------
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
2013/2014 Total: 200cm
2012/2013: 140cm
2011/2012: 103cm
2010/2011: 213.5cm
2009/2010: 97cm
2008/2009: 232cm
2007/2008: 291cm
2006/2007: 84.8cm
LAST 11 YEAR AVERAGE: 158cm

Travis
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snowgeek93
post Mar 9 2017, 07:44 PM
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You guys definitely deserve some lake effect down in Hamilton. Been a rather rough season for you guys.


--------------------
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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MrMusic
post Mar 9 2017, 08:23 PM
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QUOTE(travis3000 @ Mar 9 2017, 06:58 PM) *
MrMusic the ingredients are there if this scenario plays itself out. We are still many days away so things can change. But from todays GFS runs, the Burlington to Hamilton area could see accumulating snow off Lake Ontario for the first time this winter.

Keep your fingers crossed!


yahoo!! Yea, I realize we're many days away. But to actually have some potential is fantastic!


--------------------
Winter 2016-2017

Dec 2016: 30cm
Jan 2017: 5cm
Feb 2017: 7cm
March 2017: 35cm!! Finally!

Days with snow on the ground: 25
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MrMusic
post Mar 9 2017, 08:24 PM
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QUOTE(snowgeek93 @ Mar 9 2017, 07:44 PM) *
You guys definitely deserve some lake effect down in Hamilton. Been a rather rough season for you guys.


2 in a row...one worse than the last.


--------------------
Winter 2016-2017

Dec 2016: 30cm
Jan 2017: 5cm
Feb 2017: 7cm
March 2017: 35cm!! Finally!

Days with snow on the ground: 25
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snowgeek93
post Mar 9 2017, 08:58 PM
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QUOTE(MrMusic @ Mar 9 2017, 08:24 PM) *
2 in a row...one worse than the last.

Yeah, really could have been so much worse for us.

This post has been edited by snowgeek93: Mar 9 2017, 09:00 PM


--------------------
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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SNOWBOB11
post Mar 9 2017, 11:29 PM
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Nice run on the 00z GFS. The initial wave starts to cut earlier and that leads to a earlier and more west phase. Will be interesting to see if the other models start showing this as well. Lots of time still to go.
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Stl
post Mar 10 2017, 01:04 AM
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QUOTE(SNOWBOB11 @ Mar 9 2017, 11:29 PM) *
Nice run on the 00z GFS. The initial wave starts to cut earlier and that leads to a earlier and more west phase. Will be interesting to see if the other models start showing this as well. Lots of time still to go.



Yes it is , the amounts are around 20" using 10:1 on the GFS 00z , the Kuchera gives around 31.4" which is something i don't remember seeing for here in any models in a very long time.

This post has been edited by Stl: Mar 10 2017, 01:06 AM
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Jeremy404
post Mar 10 2017, 01:17 AM
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Any remote possibility this thing goes a few hundred km's west? laugh.gif

Many southern Ontario cities and towns outside of the LES areas are severely snow starved.
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