A weather report is, for me, like a sausage: I enjoy the end product but never really think about how it’s made. I think they both involve pork…
But then I spent time with a self-described “weather geek”, someone who made it interesting—exciting even—to pour over satellite images and surface pressure maps, puzzling together all the bits of data in order to predict weather conditions on the water for that day. The “geek’s” name is Michelle and she was my instructor for a recent boating course I took in Vancouver. We spent at least 20 minutes every morning exploring the vast amount of information on the Environment Canada website, literally drawing a picture of the South BC coast and the predicted pressure systems, frontal systems and winds. At lunch we’d go outside to check the clouds and waters off Britannia Shipyard, testing our morning predictions. Michelle’s “geeky” enthusiasm was contagious.
…And empowering. Holy moly, is it ever cool to see your prediction about the weather come to life…
I want to become more skilled and confident at interpreting weather data, especially marine weather. I’m going to practice a scenario here and share some resources along the way. I’m a newbie, so please correct me and definitely please share resources you find useful for learning about or interpreting the weather.
So, is today a good day to go kayaking?
I’m currently in Bamfield, on the West Coast of Vancouver Island and I want to know if it’s a good idea to kayak to Wizard Islet to see the harbour seals that like to haul out there.
Wizard Islet is about 1.7 nautical miles (3.1 km) from Bamfield across Trevor Channel. The swell and wind make for some big waves out there and I won’t go unless it’s calm and forecast to stay that way.
Since I want to kayak today, first thing I do is look outside: overcast but not raining, doesn’t feel windy where I’m standing—yay!—but oh, wait, I see flags flapping on the other side of Bamfield Inlet and pretty frequent whitecaps out in Trevor Channel. Hmm. Next, I check the forecast on the Environment Canada site under the Marine Weather: South Coast page. Today, I see this:
Well, red is not good. That means the wind speeds are predicted to be gale force, 34–40 knots (63–74 km/hr) on the Beaufort Wind Scale. Clicking on the West Coast Vancouver Island South section of the image gives the detailed forecast:
Doesn’t look very nice. The winds will blow at least 15 knots (28 km/hr) all day meaning there will be consistent whitecaps on the water and the waves will continue to build this afternoon as the wind picks up. And it will start raining this evening.
However, this forecast covers a pretty large area—Estevan Point is over 100km away from Bamfield, for example. For more local conditions I turn to the Lighthouse Reports, found in the Weather Conditions tab, below the map of buoys and weather stations. The nearest lighthouse to Bamfield is Cape Beale, 4.4 nautical miles away. Here’s the lighthouse report:
Lighthouse reports are made by the lighthouse keepers—yay, people!—and are entered at set times during the day. There’s a decoder page to help interpret the short hand. As of 10:45 this morning (UTC – 7hrs), Cape Beale was overcast, visibility of 15 nautical miles, easterly winds of 3 knots, with waves of 4-foot chop on top of low-to-moderate (0-4m) southwest swell*. This report was made four hours ago and the chop was already quite high; the wind and therefore the waves have only increased since then.
* “EWOS E20” is an additional remark and I can’t find on the decoder page—any ideas? [UPDATE: EWOS means “estimated winds over strait”. Thanks to Anne McCarthy from the Meteorological Service of Canada, Environment Canada for answering that question.]
Ok, so I’m definitely not going to Wizard today. Now I want to know why the weather will continue to worsen. For that, I start with the Synopsis tab:
Uh oh, lots of weather terms* here; I find Weather Wiz Kids helpful for keeping it straight. A “deepening low” refers to a low pressure system. Low pressure systems usually mean poor weather—high winds and waves—they typically move west to east and they rotate counterclockwise in the Northern Hemisphere. In B.C. this means lows come in from the ocean and often bring strong southeasterly winds. A high pressure system, by contrast, rotates clockwise, typically travel east to west, and bring fair weather with light winds. Unfortunately, no high pressure systems on the near horizon for Bamfield…
*And geographic terms: “Explorer” is a marine region far to the northwest of Bamfield, stretching from Northern Vancouver Island to Haida Gwaii.
A “frontal system” is where air masses of different densities meet, creating lots of interesting weather—usually the kind you want to avoid in a kayak. According to the forecast we’ve got two frontal systems coming, the second a cold front that will arrive in a day or two. Cold fronts usually pass more quickly than warm fronts and are followed by fair weather.
We can get a visual view of these systems by looking at the Surface Analysis chart (under the Resources tab and then Other Charts). This surface air pressure chart is updated four times a day, the most recent posted at noon. Paired with a snapshot of cloud cover taken from Google Earth, we can see a nice visual summary of all this weather:
So that’s that! Looks like I won’t be kayaking to Wizard for at least a few days, perhaps after the cold front there will be a nice day of light winds and clear skies. Until then maybe I’ll learn more about cloud types, very useful for predicting weather. If, like me, you don’t yet have the Audubon Field Guide to Weather book, you can use this handy guide to observing the clouds.
What about you—are you a weather geek, a novice like me or somewhere in between? Any handy resources to share? I couldn’t find many educational resources specific to interpreting and predicting weather patterns—if you know of any, please share!
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