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Our
WX This Summer |
As we
slowly but inexorably head into summer, the Polar Front/Jet Stream
commence their annual migration northward, reaffirming our expectations
that summer is coming.But this shift also encourages the incursion of warm humid air, which clashes with the occasional burst of cold dry northern air. The ensuing turbulence and updrafts give rise to heavy rain, thunderstorms, and sometimes hail. The instability, associated with a severe pressure drop and strong winds can also result in Downbursts and Tornadoes. A Microburst is a severe small scale downward rush of cold air which spreads outward as it reaches ground level. The rate of descent can reach 2000 metres per minute! In both cases the boundary between complete destruction and being left unscathed is often a very sharp line!
Water spouts, as reported on the Great Lakes, are smaller, less powerful twisters, that occur over larger water bodies. They also should be given a wide berth.
These weather phenomena seem to be on the increase. But with the rapid suburbanization of the countryside, and proliferation of video-cams, severe weather is now reported more frequently than it was in the past.
In Southern Ontario we are seeing more evidence of tornadoes and downbursts. Still, we might console ourselves with the realization that we are on the distant fringes of "Tornado Alley", Oklahoma-Kansas-Iowa, and the Southern USA.
This is not to say that we should be complacent.
Listen to your TV Weather Channel for updates. Tune in to the club repeaters but only report very unusual conditions as requested by the CANWARN net controller.
Tornadoes, and microbursts are usually difficult to foresee. Therefore it is important to be observant during all severe weather. But when the real thing approaches, seek shelter. Pedestrians should seriously consider approaching the nearest home and requesting refuge. If at home find a secure glass free location, preferably in the basement. A mattress pulled over you can be a life saver. If out in the open find a depression. Vehicles are not secure as a refuge. Strong winds can easily flip a car. Flying debris and glass are a very serious threat. A bridge overpass provides no real shelter. Never take unnecessary risks.
Larry VE3LGN