Major snow squall event Sunday 20th

[Roger Smith]

A blizzard-like snowstorm is likely to develop across many parts of the Great Lakes region on Sunday (Jan 20th) as deep low pressure moves rapidly east under the steering influences of a very tight jet stream, dragging down the coldest air of the season from the central Canadian arctic across the open Great Lakes. As temperatures have been fairly mild since November, water temperatures are closer to mid-December normals in the lower lakes and Lake Erie has less ice cover than usual for this stage of winter.

 

Overall, the system looks almost as intense as the infamous Jan 26, 1971 outbreak that created massive whiteouts and local accumulations of 50-75 cm (20-30 in) in the Georgian Bay snow belt of south-central Ontario. That storm stranded many people in such areas as Collingwood and London Ontario, and I would imagine also in upstate NY. This may be similar although not quite that strong.

 

The map below shows my estimates of total snowfall from the combined synoptic-scale snowfall of about 10-20 cm (4-8 in) and localized squalls, from 00z Sunday to 12z Monday. Most of this snow will be on the ground by Sunday evening. Winds will be in the range of 35-55 mph from W veering to WNW then NW during the squall phase, but eventually wind directions will veer around to northerly and may turn more to east late Monday bringing the other set of lake effect squall zones into play.

 

 

The synoptic scale snowfall will be increasing from about 4-6" in the Lake Superior region to about 10-12" in the Ottawa valley, then lake enhanced squalls will swell totals to 20" or even 30" in some parts of the region such as southern Georgian Bay and near Watertown NY. Highway closures can be expected by Sunday mid-day in parts of south-central Ontario and possibly one or two places in Michigan, and by afternoon or evening in NY and possibly PA/OH.

 

Only trace to one inch amounts seem likely on the coastal plain but 3-6" falls will be captured by the height of land in MD and PA, with local 6-10" in WV due to orographic uplift.

 

This will be a shock to the system in the Great Lakes region which has not seen an unusually severe snowfall event this winter. They will be a little more "with the program" in Ottawa, Montreal and Vermont where one or two big storms have already hit.

 

The meteorological set-up:

 

http://www.weatheroffice.gc.ca/data/model_forecast/3294_100.gif

 

Another view can be read here, where also you can track developing snowfall events in Ireland and the UK:

 

http://www.meteotimes.net

 

 

 

 

 

[Sub_Zero]

Thanks Roger, looking forward to it!

[OSUmetstud]

yeah, I don't agree with this...

[Thunder Road]

6" of LES at Valpo off WNW flow?  Should be one for the record books!

[OSUmetstud]

the tug will be lucky to get 6-12" on Sunday...3-6" for the Chautauqua Ridge.

 

ESE of Georgian Bay will do well.

[blizzardof96]

the tug will be lucky to get 6-12" on Sunday...3-6" for the Chautauqua Ridge.

 

ESE of Georgian Bay will do well.

What are your thoughts on accumulations in toronto?

[Roger Smith]

Snowfall map runs to 12z Monday which allows for a period of more NW to N wind direction near Lake Michigan. However I would bow to any specific local knowledge on northern IN lake effect. Looking at the guidance and current developments in western Canada, I am expecting this to produce snow at 5-10 cm (2-4 in) an hour in squall bands. Won't take long to pile up and then LES often has low density too. Highways will flash freeze on Sunday morning, another concern for road managers.

 

You probably wanted OSU's thoughts on Toronto but my forecast would be 2-5 cm lakefront to 5-10 northern suburbs to 10-20 cm Hwy 9. Even that mega-squall event in 1971 left only an inch in downtown Toronto, the synoptic scale snow with that hit Sudbury. This one might generate a bit of frontal snow as well as long-distance Huron squalls. Major squall band in this pattern would be likely just north of Barrie and through Orillia, that's where I could imagine 50 cms falling.

[blizzardof96]

Snowfall map runs to 12z Monday which allows for a period of more NW to N wind direction near Lake Michigan. However I would bow to any specific local knowledge on northern IN lake effect. Looking at the guidance and current developments in western Canada, I am expecting this to produce snow at 5-10 cm (2-4 in) an hour in squall bands. Won't take long to pile up and then LES often has low density too. Highways will flash freeze on Sunday morning, another concern for road managers.

 

You probably wanted OSU's thoughts on Toronto but my forecast would be 2-5 cm lakefront to 5-10 northern suburbs to 10-20 cm Hwy 9. Even that mega-squall event in 1971 left only an inch in downtown Toronto, the synoptic scale snow with that hit Sudbury. This one might generate a bit of frontal snow as well as long-distance Huron squalls. Major squall band in this pattern would be likely just north of Barrie and through Orillia, that's where I could imagine 50 cms falling.

Thanks for posting your thoughts. We usually get some snow from these LES outbreaks but nothing too substantial. I am thinking a long lasting event is likely with moderate bands across southern ontario. Barrie to meaford will face the brunt of the GB squall which may extend into the eastern suburbs of toronto. With delta-t values pushing 20C areas along the GB shores may pick up 15-30cm of snow over a 3 day period. The huron squall should set up from kincardine/goderich to just north of the london area with up to 30cm possible. Bands should shift from a WNW to ESE orientation to more of a NNW to SSE direction as we advance into the beginning of next week.

[OSUmetstud]

What are your thoughts on accumulations in toronto?

 

through midweek?  probably a couple inches.  

[WEATHER53]

How about lake effect for Laurel Highlands?

[andyhb]

I need more than an MS Paint (and a pretty ugly one at that) map to be convinced.

 

I mean at least draw it on a properly scaled map...the PA border is not that far south lol, and what on earth is wrong with Indiana. And my lord, why is IL and WI's border as longitudinally extensive as Ohio? Did IL and WI eat a chunk of IA for breakfast?

[Roger Smith]

Andy, I realize you guys had that success with the bait-and-switch on Microsoft Paint last summer. Of course I don't employ professional graphic artists to make posts on amateur weather forums, I am not a highly paid employee of a government agency, just a weather enthusiast and researcher. If you can do better yourself, then feel free to do so.

[Ellinwood]

Andy, I realize you guys had that success with the bait-and-switch on Microsoft Paint last summer. Of course I don't employ professional graphic artists to make posts on amateur weather forums, I am not a highly paid employee of a government agency, just a weather enthusiast and researcher. If you can do better yourself, then feel free to do so.

 

You can download and learn Gimp. It's a free program that you can use to make professional-quality (or at least nicer looking) maps. You do not need graphic artists or money to make good graphics... just need to take some time learning the tools.

[mappy]

My head exploded

[andyhb]

You can download and learn Gimp. It's a free program that you can use to make professional-quality (or at least nicer looking) maps. You do not need graphic artists or money to make good graphics... just need to take some time learning the tools.

 

Yeah, or I think it's called Seashore now if I'm not mistaken.

[Ellinwood]

Yeah, or I think it's called Seashore now if I'm not mistaken.

 

That looks like a MAC version of Gimp... Gimp is currently on version 2.8 and still going strong: http://www.gimp.org/

[Ottawa Blizzard]

Snowfall map runs to 12z Monday which allows for a period of more NW to N wind direction near Lake Michigan. However I would bow to any specific local knowledge on northern IN lake effect. Looking at the guidance and current developments in western Canada, I am expecting this to produce snow at 5-10 cm (2-4 in) an hour in squall bands. Won't take long to pile up and then LES often has low density too. Highways will flash freeze on Sunday morning, another concern for road managers.

 

You probably wanted OSU's thoughts on Toronto but my forecast would be 2-5 cm lakefront to 5-10 northern suburbs to 10-20 cm Hwy 9. Even that mega-squall event in 1971 left only an inch in downtown Toronto, the synoptic scale snow with that hit Sudbury. This one might generate a bit of frontal snow as well as long-distance Huron squalls. Major squall band in this pattern would be likely just north of Barrie and through Orillia, that's where I could imagine 50 cms falling.

Roger, to clarify, is this total snowfall through midweek, or for Sunday into Monday only?

[Roger Smith]

Will post a more detailed Ontario map in a while, studying the guidance ... thanks for input. The graphics question can be a distraction from what is essentially just a call for heavy snow squalls regionally.

[Jim Marusak]

doesn't the main metro toronto area usually only get hit with decent sustained squalls mainly with a 250-270 squall off southern lake huron wrapping around that glacial escarpment near london, a 350-squall off of georgian bay down the 400/404, or an 090 squall from lake ontario on the top side of a low? the setup I'm seeing gets more hamilton/london/goderich to the south, and barrie/orillia/muskoka/parry sound/huntsville and maybe even north bay/petawawa off of georgian bay for southern ontario. the only way toronto sees over 2 cms with this is if the thermal trough does something real screwy, imho.

[Ottawa Blizzard]

doesn't the main metro toronto area usually only get hit with decent sustained squalls mainly with a 250-270 squall off southern lake huron wrapping around that glacial escarpment near london, a 350-squall off of georgian bay down the 400/404, or an 090 squall from lake ontario on the top side of a low? the setup I'm seeing gets more hamilton/london/goderich to the south, and barrie/orillia/muskoka/parry sound/huntsville and maybe even north bay/petawawa off of georgian bay for southern ontario. the only way toronto sees over 2 cms with this is if the thermal trough does something real screwy, imho.

I agree with regard to Sunday and Monday. According to the GFS, Tuesday and Wednesday might see more in the way of lake snows into the north end of Toronto into Markham, Vaughan and Richmond Hill. This being said, I believe this thread was intended for Sunday and Monday.

[Jim Marusak]

I agree with regard to Sunday and Monday. According to the GFS, Tuesday and Wednesday might see more in the way of lake snows into the north end of Toronto into Markham, Vaughan and Richmond Hill. This being said, I believe this thread was intended for Sunday and Monday.

 

that looks right on both accounts. i'm thinking 290 for sunday and early monday.

 

but once that thermal trough comes through on Tuesday, if you can kick the flow with that to the east for ~12 hrs, a quick burst of 5 cms or so can happen. i got burned once that way when i worked up there. the band set up, was migrating down the lakeshore from trenton/belleville, and instead of keeping moving and orienting towards oakville and hamilton, it parked itself when it got to the scarborough bluffs, and momma nature told me i was #1 that day.

 

from that point forward, she has used me as a whipping boy for screwy things when i do the cast ever since.

[andyhb]

That looks like a MAC version of Gimp... Gimp is currently on version 2.8 and still going strong: http://www.gimp.org/

 

Ah, I see, yeah I have Seashore on my laptop.

[Roger Smith]

 

Updated forecast map for snowfall in cm for Sunday-Monday including another 12h time period compared to original map, partly because this event looks to be reorganizing into two bursts of lake effect, one Sunday afternoon and another Monday afternoon.

 

Please note that a flash freeze effect is likely on all regional highways early Sunday as temperatures fall rapidly. Snow outside of lake effect zones and south of a Parry Sound to Montreal line would be mainly from frontal band and any heavy squall remnants that make it outside the usual zones.

 

Here's what I noted about snow squall vectors and target areas in my years of living and researching in Ontario.

 

250-260 deg heaviest across Bruce-Grey and into north Muskoka, Parry Sound, south Niagara and Buffalo NY, Prince Edward County (the peninsula in eastern Lake Ontario) Kingston to Brockville and outer Long Point, also Manitoulin Island

 

270 deg heaviest across south Muskoka, north Simcoe County, parts of Bruce-Grey and south tip of Prince Edward into Watertown NY ... with strong winds, long fetch into Haliburton region, "south towns" of wNY

 

280 deg heaviest across Bruce-Grey, central Simcoe (Orillia) into northern Kawarthas ... parallel half-strength band Huron-Perth, would hit between Watertown and Oswego, 30-50 miles south of Buffalo NY

 

290-300 deg heaviest for Barrie and London-Lucan snow belts, Syracuse NY, third band between these in southern Bruce nw Wellington counties

 

310-330 deg heaviest for London west to Strathroy depending on exact vector, Alliston to Oak Ridges, Rochester NY, nw PA and ne OH

 

340-360 deg heaviest for Sarnia, Cleveland OH, Lockport NY, Collingwood to Shelburne ON

 

010-040 deg heaviest for Niagara north, thumb of lower Michigan, Meaford ON, could get into IAG-BUF

 

050-080 deg heaviest for Hamilton-Burlington, Saginaw Bay,

 

090-140 deg heaviest for Toronto lakefront to Oakville, one case made it inland to Georgetown ON (1-15-1965)

 

150-230 deg often too wet or mild for real squalls but if cold enough, odd places like Whitby-Oshawa, St Thomas ON, also French River towards Sudbury and North Bay ON, central Niagara

 

240 deg heaviest Port Hope-Cobourg, parts of Bruce-Grey, north Parry Sound, most of Niagara

 

I've lived in the snow belt, know all about the wall of snow effect, where you drive from sunshine to zero vis and into that q.s. band of S+ then days later you can drive through that same area and see the snow cover differences over 1-2 km, amazing stuff ... used to live north of Orillia and some days the wall of snow would be 5 kms north, some other days 5 kms south, figured out the wind directions needed for those (something like 265 and 285 deg). Where I lived we needed 275 deg and we could be in the snow for hours at a time at 5-10 cm an hour, then it would let up if the wind changed direction even 5-10 deg.

 

 

[blizzardof96]

that looks right on both accounts. i'm thinking 290 for sunday and early monday.

 

but once that thermal trough comes through on Tuesday, if you can kick the flow with that to the east for ~12 hrs, a quick burst of 5 cms or so can happen. i got burned once that way when i worked up there. the band set up, was migrating down the lakeshore from trenton/belleville, and instead of keeping moving and orienting towards oakville and hamilton, it parked itself when it got to the scarborough bluffs, and momma nature told me i was #1 that day.

 

from that point forward, she has used me as a whipping boy for screwy things when i do the cast ever since.

Where did you work for as a met in toronto? I am from toronto and from experience hamilton/burlington gets hit harder with bands off of lake ontario in NE flow events but in january 2011 we got about 8" of snow from a LES band overnight. It was a nice surprise!

[Jim Marusak]

Where did you work for as a met in toronto? I am from toronto and from experience hamilton/burlington gets hit harder with bands off of lake ontario in NE flow events but in january 2011 we got about 8" of snow from a LES band overnight. It was a nice surprise!

i worked for the now bought-out World Weatherwatch between oct 1998 to Feb 2006, then at the buyer's place, Pelmorex/The Weather Network between feb and july 06.

 

if the bands go 030-060, yea hamilton (especially near hamilton mountain/mount hope/hwy403)/niagara/oakville get hammered. but if they go 070-090, toronto's gotten hit more than a few times. it's just not usual to go 070 to 090 or 100 over there. but you are right, when they get clocked, they get clocked.

 

and roger, most of what you said is on the money. but 220 squalls did happen on occasion. and when they did, peterborough did get hit with one of those (i drove through one of them one time on tch-7, not fun). and 210 to 230 squalls usually head into southern niagara (port colbourne and environs) as well as long point (southeast of london). also, i've seen 210-230 squalls off of georgian bay/lake huron make it up at times to north bay (yyb). sudbury usually gets lake-enhanced stuff with a 160-210 wind.

[Ottawa Blizzard]

i worked for the now bought-out World Weatherwatch between oct 1998 to Feb 2006, then at the buyer's place, Pelmorex/The Weather Network between feb and july 06.

 

if the bands go 030-060, yea hamilton (especially near hamilton mountain/mount hope/hwy403)/niagara/oakville get hammered. but if they go 070-090, toronto's gotten hit more than a few times. it's just not usual to go 070 to 090 or 100 over there. but you are right, when they get clocked, they get clocked.

 

and roger, most of what you said is on the money. but 220 squalls did happen on occasion. and when they did, peterborough did get hit with one of those (i drove through one of them one time on tch-7, not fun). and 210 to 230 squalls usually head into southern niagara (port colbourne and environs) as well as long point (southeast of london). also, i've seen 210-230 squalls off of georgian bay/lake huron make it up at times to north bay (yyb). sudbury usually gets lake-enhanced stuff with a 160-210 wind.

I actually remember you telling me about your years in Toronto. Correct me if i'm wrong, but I recall you weren't a fan of the CBC. lol

 

Here's hoping Toronto gets pounded this week!

[Jim Marusak]

I actually remember you telling me about your years in Toronto. Correct me if i'm wrong, but I recall you weren't a fan of the CBC. lol

 

Here's hoping Toronto gets pounded this week!

the cbc weather people, correct.

 

but i am a fan of "the debaters" on cbc radio as well as "Vinyl Cafe" on occasion. I do watch the "mercer report" via youtube . just too bad much music and citytv got neutered, as i understand it. but a person i used to work with when i was at the weather network is one of the weather people at citytv (chris potter).

[Roger Smith]

Looks to be quite intense at this time, gusts to 62 kts at Michigan City IN and lightning across s/c MI.

 

Dynamics could create mega-squall bands very quickly this morning off Lake Huron and Ggn Bay, also Lake Erie. Hoping that OPP have a good warning on this, they may need to close roads north into Simcoe County to prevent traffic chaos. What I remember from Jan 1971 is that everything hit almost instantly and conditions went from similar to this present pre-frontal mild spell to blizzard and bitter cold. Temp dropped from +1 to -15 C. Could be similar later today.

 

Wind damage potential in Toronto, Buffalo and other exposed locations. Gusts to 55-60 mph possible.

[blizzardof96]

We have went from an intense thunderstorm last night to thundersnow this morning. Winds are very strong and bands are picking up with blizzard like conditions up north and lots of blowing snow.

[Ottawa Blizzard]

Roger, could you post your thoughts for the potential lake effect in Toronto on Tuesday and Wednesday?