Weather Part I – A Brief Introduction to Weather Reports For the next few weeks, I’ll be drawing on my experience as an airline Flight Dispatcher to give some insight to how weather works, and how to interpret weather and dark sky reports to get the most use out of your scope that you can. Let’s face it – for the next few months here in Vancouver, we can expect a lot of poor seeing. That’s not to say we won’t get ANY observing done, it’s just that the price we pay for not having to shovel snow all winter, is a lot of overcast skies. There are a few key things you can look for in the weather forecast that will give you some insight into what kind of effect there will be on seeing. We’ll use the Environment Canada weather report as our example, because it’s succinct and easy to interpret. First thing you should know is that the weather forecast is based on the prevailing weather within a radius (usually about 9 km) of the weather reporting site. For the Vancouver area, this area covers the entire metropolis, with the borders roughly corresponding to the mountains of the North Shore and inland to about Abbotsford. The quick-view image will show the prevailing weather within this area – if it’s sunny everywhere but the North Shore, for example, this will be a Partly Cloudy image. Technically wrong everywhere, but as right as one image can be for the area. Next thing to check is the temperature – not just the daytime high, but the night time low as well. The normal pattern – as I’m sure you’re all aware – is for lower temperatures overnight than in the day. Finally, there’s a brief text write-up to provide more detail, exceptions, and qualifiers. Things you may expect here include “cooler temperatures inland,” “except cloudy along the North Shore,” or “Periods of rain”. These details will give you a better idea of what the atmosphere is doing. There are a few other tools on Environment Canada’s site that we’ll touch on, such as radar, satellite, and atmospheric modelling. Environment Canada weather.gc.ca Vancouver 7-day Forecast weather.gc.ca/city/pages/bc-74_metric_e.html NASA Video of weather in the Eastern Hemisphere https://youtube/watch?v=T66tLRR9drY&src_vid=JZXErLns1mM&feature=iv&annotation_id=annotation_397244329
Posted on: Fri, 31 Oct 2014 17:10:36 +0000
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