(Reprint from 2008 Blogspot blog – Weather Basics for Photographers Part 1)
I’m sky head. I love the dynamics and form a complex sky gives my photos. I also love filtered light, light holes and all things a great sky can add to an image. Since most commercial weather services rarely give the detail I need to make a travel or shoot decision, I frequently if not obsessively turn to the National Weather Service (NWS) as they are primary source of weather forecasting in North America and beyond. They run the mainframe weather models and in turn deliver the core data to meteorologists for their forecasts. Although NWS’s websites are somewhat a mess, if you want as much detail as possible, this is where to go. Here are some general weather forecast strategies that work well with their services.
1) Know your zone. Most areas have very specific micro climates amd land features the regularly affect the more general pattern. Are you in a valley? On the coast? What are the averages for a given season and what anomalies are more or less common for that season? A mid July clear sky high desert might seem the norm, but in fact, areas like the Southwest regularly receive the bulk of their precipitation from the Monsoonal surges that come and go depending on the steering winds or flow setup by a high pressure zone centered on the four corners region. Once the relative humidity reaches a certain point and there’s enough solar heating, afternoon Cumulus will develop everyday and often for many days after the “high” has moved on as residual moisture slowly dries. Living by the coast as I do, there’s often a predictable setup in the Summer–read boring–and a much more dynamic set of conditions the rest of the year2) Follow the models. All NWS local zones have a discussion page where meteorologists summarize in their own peculiar lingo the results of the various computer simulations that are run a couple of times of a day. What we get with typical media forecasts is an averaging of a much deeper data set. The discussion pages, if you can take the time to understand some of the terms, will give you a better feel for the certainty of forecast, pointing to the different possible outcomes rather than just the probability of one–important distinction.
3) Use the satellites and radar. A picture is worth a million words–hey that’s why we’re in this business. Running the animations of the visible, infrared (great at night) and maybe water vapor images can really give you an excellent clue as to what is happening right now and what’s possible to come in the next 24 hours. It’s often the case that when the models get confused and differ, the satellite imagery offers better insight. Radar is key for tracking local precipitation and storm movement.
4) Know your clouds. While a towering Cumulus Nimbus might offer the grand skycape, it is the mid and upper level clouds that give us dependable filtering and brilliant sunsets. Understanding what type of clouds occur as certain types of storms approach and leave is key here. It’s often the case that high clouds will spread out in front of an approaching storm. If you’re into dawn and dusk settings, then knowing when the storm is expected to approach and leave relative to direction is absolutely required knowledge. Red skies at dawn happen when you have an approaching storm from the west and red skies at dusk happen when the storm is leaving. Of coarse, red skies can happen at dawn or dusk when there are clouds, especially the high ones, that the sun can get underneath. The typical Summer fog layer at the horizon where I live mutes probably 90% of the colors during sunsets as even if there’s a good cloud setup, the sun can’t get underneath them. So, look for clarity of atmosphere in the sun’s direction–something deserts are really good at.
Here’s a handheld stitched panorama looking into the center of a deep low pressure center often referred to as a Vort Max (vorticity maximum). Note the abundance of of cloudless space in the “eye” for light to get through.