The Newfoundland blizzard

Courtesy of CNN

I am very late onto this story about a blizzard in Canada, maybe because of all the excitement concerning MSLP in excess of 1050 hP in this country. Anyway back to the real world and a blizzard in Newfoundland where the 76 cms of snow broke the daily snowfall record last Friday. I can’t really add anything to the news report from CNN, but I can produce a couple of plotted grids of SYNOP observations for the last five days to give you a flavour of what happened from two nearby locations in St John’s. One of these is named St John’s West climate (#71250) in my stations database, and the other St John’s (#71801) is the airfield, that lies less than 12 km to the north. St Johns was alway a favourite diversion back in the 1970/80’s for any RAF aircraft crossing the Atlantic, and as an assistant you would without question have to signal to get the latest TAF and METAR for both there and Gander. Anyway less of the nostalgia.

Comparison of observations

If you take a look at the plotted observations in the grid you’ll probably be wondering how incredibly well sheltered the climate station is when you compare its winds to those at the airfield. Bizarrely the reported snow depth from the AWS at the climate site actually decreases from 49 to 35 cm during the storm! If it wasn’t for the pressure, which correlates well with the one from the airfield, I would thought that these two stations were many miles apart.

Wind Speeds

First up the winds from the airfield are extremely high – they look way too high – but I have checked and there coded as knots as Canadian SYNOPs usually are. The Canadians never report gusts which doesn’t help, but the reported mean speed should be for the latest ten minutes before observation if they are following the WMO guidelines – but who knows they could be two minute means.

Snow Depths

The other odd thing that you might notice is the six hourly snow depth. I’ve said this before about snow depth observations (because although I am no expert I did have to estimate snow depth as part of my job as an observer) and that’s: how could you possibly report a level depth of snow in a howling blizzard like this? By the look of things, mean wind speeds at St John’s airport were in excess of 50 knots for twelve hours, and at 03 UTC the mean speed was reported as 68 knots, that’s hurricane force 12, and the snow would have been severely drifted. All I can think is that the AWS is equipped with some kind of fancy heated snow gauge sensor that reports an estimated level snow depth from the water equivalent of the snow as it falls, because if you notice the rainfall observations never miss. I would have expected as much damage from these winds as from the snow of the blizzard, they obviously make them very tough in Newfoundland!

And here’s a look at the 03 UTC plotted chart on Saturday morning for eastern Canada and the extremely tight northerly gradient.

And just to see where the two stations in St Johns actually are with respect to each other. They are less than 12 km as the crow flies, not that they were many flying on the night in question!

Courtesy of Google
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