I recently “discovered” on the local NWS website the Satellite Water Vapor Imagery data for our area, and I’m quite fascinated by it! The official description of this data is as follows:
Water vapor satellite imagery depicts moisture content in the middle and upper layers of the atmosphere. Lower level moisture is not depicted in these images. Moisture transport over large distances generally happens through the middle and upper layers of the atmosphere. Hence these images will depict moisture coming into the Southwest from the Gulf of Mexico or across Texas. Additionally, weak disturbances from the east are best tracked through water vapor imagery.
The imagery looks like this when viewed online. The is a screen capture of one frame of data:
Water Vapor Imagery
Basically, what this shows is the amount of moisture that is in the upper atmosphere. This may be in the form of clouds that you see, but often it is not. Water vapor literally surrounds the earth, but is unevenly distributed due to things like oceans, lakes, rivers, deserts, arid areas, etc. For instance, in the image above, you can see a lot of water vapor coming up from the southwest into places like Arizona and New Mexico, which are traditionally dry regions. Areas like the Pacific Northwest, which are usually wet, have much less than normal. This is all due to seasonal shifts in winds and weather patterns, which change the flow of moisture around the planet. By looking at an image like this, you can get an idea of how much moisture is available in your area…moisture that could turn to rain or snow!
When I drove to work this morning, around 9AM, the sky was almost perfectly clear. A few high cirrus clouds, but nothing aside from that…just blue sky. Below is a snapshot from my phone on what the sky looked like around 1:30PM today:
Quick Storm Development
Since this picture was taken, our area has seen multiple Severe Thunderstorm alerts, along with several Flash Flood warnings! It absolutely amazes me how quickly the weather can turn in our area of the wood, and why it’s always important to keep an eye on weather when outside doing fun things. Dry washes and rivers can turn into raging torrents without a single drop falling in your particular area. Always know the weather!
I was flying to Seattle earlier this week, and snapped this picture from the plane. I love how clouds look from the top! Notice the vertical development punching it’s way through the deck!
View From The Top
I have created a new website aimed at showing people the best locations to take lightning and storm pictures. It’s called Lightning Shot Spots and I just launched it today! So far it’s a bare bones site while I work to collect location data (provided by users like you!), but I have plans to develop it into a world class storm photography resources. So, head over, take a look, and please contribute a location if you have one. Thanks!
When you start seeing vertical development in storm clouds, there’s a good chance rain is on the way. Here’s a picture of some clouds outside right now, and the associated radar image from my iPhone.
I stumbled across this today, and thought it was worth sharing. There are lots of ways to forecast the weather without relying on gadgets. Knowing how to do it old school is a great skill to have, and helps you understand the fundamental properties of weather. Check out this graphic, and have fun learning!
So, not the best picture in the world, but I was able to catch some growing mamatus clouds this morning on my way to work. I had to use my iPhone camera to take the pic. I love how these clouds look!
Mamatus Clouds in Tucson, AZ
A couple days ago, as a storm was moving out of the area, we got some classic cirrus clouds in the upper atmosphere. These types of clouds are very high in the atmosphere, are traditionally thin with wispy strands, and can often herald the arrival of a storm (in this case they were remnants of a previous storm). Cirrus clouds like to live at levels above 26,000 feet (8000 meters), and are formed when water vapor freezes into ice crystals. The lack of moisture at such high altitudes is one of the reasons these clouds tend to present so thin and wispy.
Cirrus Clouds in Tucson, AZ
A lot of times in Tucson we see hair like filaments of ice crystals precipitating out of the clouds in the form of what’s called virga. These streaks often indicate the difference in the motion of air between the upper part of the cirrus cloud and the lower air below it. It appears as though rain is coming from the cloud, but it’s actually ice crystals, most of which evaporates before it hits the ground (especially in Arizona). On some days, cirrus cloud development is so extensive that they become virtually indistinguishable from one another, forming what’s called cirrostratus clouds.
Another type of cirrus cloud that you’re already very familiar with is the condensation trails, or contrails, seen in the sky coming from planes. These trails are basically artificial clouds formed by the exhaust of aircraft engines. As the hot exhaust gases cool in the surrounding air they may precipitate a cloud of microscopic water droplets. If the air is cold enough, this trail will comprise tiny ice crystals. On some days, with a high level of air traffic, you can see contrails crisscrossing the sky, and these contrails often hang around for some time. It’s pretty neat!
Clouds are very cool, and an obviously integral part of weather. I intend to eventually go through all the various cloud types, hopefully using images I’ve shot with my camera. If you understand why a particular cloud type is in the area, you have a good idea of what sort of weather might be on the way.
