Tips on interpretation of Ontario weather reports

[Roger Smith]

Ontario weather stations and forecasting northeast U.S. weather -- just a few ideas

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Long ago there was a time when I worked in a forecast office in PA for a company that you may have heard of (unless you arrived on the weather planet yesterday).

One thing I remember (vaguely) was that perhaps understandably, a lot of my U.S. friends in the weather business have somewhat vague ideas about the landscape across Ontario despite the fact that air masses are frequently crossing that province on their way east or southeast towards the forecast regions, and sometimes the vitally important "tomorrow" forecast (or sooner) is unfolding over that landscape.

As we all know, forecasters pro or amateur get a feel for weather patterns in part from the models, and in part from poring over observations from places upstream that are getting the weather today that you're trying to predict tomorrow. We all have our ideas about how the weather at say MSN or MKE might play out when it arrives over NY or CT or MA.

So my little thread here is to give you some ideas about station exposure and characteristics so that if you're looking at Canadian data from Ontario and in particular southern Ontario, you might get some additional "feel" for how air masses are evolving. Maybe some of our other Canadian posters will add some details. By the way, I used to live in Ontario (from 1957 to 1995) and observe, forecast and experience the weather there.

Southwestern Ontario

As we go along here, you're going to pick up a few regional terms that might seem obscure. Bear in mind Ontario was settled two centuries ago and used to be mainly the part south of Sudbury to the Ottawa River. For example, in London, Ontario there is a university called The University of Western Ontario and back in the 19th century the Lake Huron region was "western Ontario" even though you might figure that would be west of Lake Superior. Canadians call that part northwestern Ontario. More about that in each region.

SWO (as it's abbreviated) is very similar to lower Michigan, except that people have jobs. Sorry, we are a race of comedians. But some parts are higher than you might think. Let's start with Wiarton on the Bruce peninsula (YVV). This is a snow belt location similar to Pellston MI in some ways. The wind tends to blow a bit more westerly in given situations than geostrophic wind would suggest. It is also not a very windy location probably due to the Niagara escarpment and mesoscale influences favouring troughs over Lake Huron. YVV is closer to Georgian Bay than Lake Huron. You should always add a bit of wind speed if you're considering it as an analogue for a forecast. Going south inland you come to Mount Forest (WMN) which is quite high up on a plateau generally 1200-1500 ft above sea level. It's fairly flat but slightly rolling country upwind, and once again, this station doesn't often report very strong winds for given situations. To the west on Lake Huron is Goderich (WGD). It's similar to Muskegon and plays out about the same way. At the south end of the lake is Sarnia (YZR) which can be violently exposed to NNW to NE winds and might be a good one to check when there's a developing northerly for ROC or somewhere on Long Island. Further southwest, Windsor (YQG) is much like DTW, they tend to respond about the same in most situations. Going east, you'll be familiar with YXU (London airport) but keep in mind, it is east of the city, and just slightly east of a persistent heavy snow squall zone that is more likely to set up over the city or western suburbs. If you're seeing reports of moderate snow at YXU in a w.n.w. wind, it probably means S+ very close to the north. YXU is well exposed to west winds and east winds but north winds tend to be under-reported due to rolling forested land in that direction.

Some of those comments about YXU would apply to Waterloo-Wellington airport near Kitchener. It has better exposure to the west than other directions and is often just outside heavier squall bands. Hamilton (YHM) is an airport station well south of the city and reasonably well exposed in all directions but there is a regional meso-scale climate tendency for shallow inversions over Lake Ontario to creep just past this site (which is above the Niagara Escarpment) and keep winds in an easterly flow then give way to a sudden shift to westerly. There is a sort of "la Porte anomaly" storm zone to the north of YHM towards western Lake Ontario.

The Niagara peninsula is a sub-region and not really considered southwestern Ontario. YSN (Saint Catharines) is a somewhat low-down site that won't always reflect full wind conditions, and it tends towards a lot of oscillating wind patterns as Lake Ontario regional flows compete with Lake Erie regional flows. The peninsula is not really wide enough to get true lake breeze boundary conditions. Going back west along Lake Erie, some stations along there especially Port Colborne light and Long Point are very exposed to Lake Erie and are good sites for estimating winds to come in BUF in strong westerlies but not so much in east or south winds (they will be weaker at BUF).

Toronto (GTA) region

The Greater Toronto area or "golden horseshoe" is a highly urbanized zone around western Lake Ontario. We mentioned YHM already, but Burlington Lift Bridge is a site on a high harbour bridge so it gets some strong gusts in westerly and easterly winds. In some situations it can be buried in a stable marine layer, as can Toronto City Centre airport. The lake breeze zone in Toronto is strong almost to the main airport (YYZ) in some situations, but there is also a regional southeast wind that can hold back fronts to the west of the Niagara Escarpment. This can lead to some persistent low cloud and fog situations at YYZ that may fool you a bit for downstream analogues where there is no situation like Lake Ontario present. The "Buttonville" airport site is northeast of the city and not quite as well exposed to strong winds as YYZ. Further east, Cobourg (WNC) on Lake Ontario is very often influenced by a stable layer and light wind flows, lake breezes and fog. It's rather similar to ESC. The terrain to the north of there and most of Toronto, is rolling to hilly in places, so there is a slight downsloping effect in Toronto's climate when winds are north through west.

Just a brief note about the Niagara Escarpment, which starts in western NY (facing north) and over which the two "falls" drop, this continues on around western Lake Ontario, then north to southern Georgian Bay, then it faces northeast all along the shore of Georgian Bay's western coastline up the Bruce peninsula ... then it falls away under Lake Huron and resurfaces on Manitoulin Island, that large island in northern L Huron (world's largest freshwater island), faces north but not all that high any more, and runs along through the smaller islands into Michigan's u.p. where it continues to face north but in a rather small version of its former 300-500 ft profile. It ends up facing west as it runs through Wisconsin's Door Peninsula and I guess it just gets buried in glacial sediments in eastern WI someplace. In some parts of Ontario it is quite a high barrier for example around Collingwood on Georgian Bay where the elevation rises over a thousand feet in places from lakeshore to plateau.

Central Ontario

The country between Georgian Bay and the Ottawa River valley is generally known to Ontario people as "central Ontario." It is really south-central but that would apply more to northern suburbs of Toronto. Central Ontario is boreal forest on the granite rocks of the Canadian shield, like northern MN or the Adirondacks. It is "cottage country" with a lot of small lakes and one or two larger ones, rolling rocky hills and small towns in river valleys. The region includes a small area south of the "Canadian shield" that is glacial outwash drumlin country like parts of wNY. That runs from Lake Simcoe east through Peterborough to north of Trenton.

Weather stations in central ON are generally not well exposed to strongest winds and need to be "upgraded" in their wind reports for some purposes. Anyone who has played golf around Peterborough will know that it can get extremely windy around the large lakes but YPQ (WPQ) sometimes reports more like 35 mph when you know you had 50 mph gusts nearby. The same is true of Muskoka airport, YQA, it is a flat open space in a large forest in rolling terrain, so it tends to sit under the stronger wind gusts in some situations. YQA is often north of very heavy snow squall bands coming in across northern "Huronia" or Simcoe County and Lake Simcoe. Any reports from Borden, Barrie or Lake Simcoe should be considered along with YQA and YPQ. Further north any stations around Georgian Bay up to Sudbury and North Bay can under-represent wind gusts considerably in northwest to northeast winds (hilly in that direction).

Northern Ontario

Just briefly, northern Ontario for Canadian residents starts around Sudbury (YSB) to North Bay (YYB) and the general idea is that all the stations are reasonably well exposed but subject to meso-scale lakeshore climates in some cases. You can take most or all these stations as being about as well exposed as New England stations and in similar terrain to southern New England inland. There are some rather large lakes that don't show up on weather charts, inland from the Great Lakes, and these can enhance winds locally. On the other hand, there is a regional flow from the southwest that can remain stable and trapped under an inversion, near Lake Superior.

Northwestern Ontario is probably too far away to include in this roundup, and in any case conditions at the main stations are very similar to INL and HIB. YQT (Thunder Bay) is better exposed to the west than most others.

Ottawa valley and eastern Ontario

These sites can be tricky to forecast and you need to interpret them carefully for New England. The Ottawa valley is relatively shallow but seems to trap cold air very effectively when high pressure is over Quebec. Readings from YWA (Petawawa) and Ottawa (YOW) can show a much weaker east wind than you're going to get out of the analogue situation in southern New England. When the wind comes in from the west it can be shielded somewhat at YWA, and there is a side valley near there that often gets wind gusts going from variable directions west through north.

Kingston on Lake Ontario (YGK) is a very marine-influenced location that rarely warms up much in spring or summer. This has an influence on wind speed considerations also. Squall lines coming southeast from the Ottawa valley or the higher country west of there often tend to fall apart when they encounter the cool stable Lake Ontario layer. You might bear in mind they will tend to regenerate over upstate NY when they encounter less stable boundary conditions again.

-- more later or if we get a discussion going --

-- and remember, metric reports go like this, 80 km/hr is 50 mph and 100 km/hr is about 63 mph.

this last item is kinda funny, remember how we had no snow near Vancouver last winter for the Olympics? Well in the same places today, we have so much snow that they're saying events might have been cancelled for that reason today, but otherwise, the conditions are perfect and the visuals are too -- huge piles of snow and bright blue skies. Oh well ... that's la Nina for ya ... but it's still green down here by sea level.

[on_wx]

As we go along here, you're going to pick up a few regional terms that might seem obscure. Bear in mind Ontario was settled two centuries ago and used to be mainly the part south of Sudbury to the Ottawa River. For example, in London, Ontario there is a university called The University of Western Ontario and back in the 19th century the Lake Huron region was "western Ontario" even though you might figure that would be west of Lake Superior. Canadians call that part northwestern Ontario. More about that in each region.

Ontario was settled in the 1600s by the French and the Jesuits

Good post, though!