Photogenic Clouds from Above and Below - Clouds of the Day - Sunday, July 30, 2023

Satellite images are useful tools for forecasters. It is not just about the pretty pictures, it’s about the details in the images that reveal developing and dissipating storm systems. Meteorologists glean a lot of information from satellite images - much more than you might expect. The images can be compared with computer model forecasts to see how well the models are performing and helps forecasters produce better forecasts than the models alone.

Here is an image from this evening. My location is Cedar Falls, Iowa located in Northeast Iowa next to Waterloo. The Altocumulus/Altostratus/Cumulus cloud pointer locates our general area. The satellite image shows what those cloud types looked like from space.

I have also pointed out many other cloud types on this image. Special note: the cool air boundary in Illinois and Indiana locates the leading edge of cooler/drier air that has spread off the Great Lakes. It is a shallow layer of cooler air and the leading edge acts much like a cold front. Scroll down to the surface map plot to learn more.

Scroll down to see what the clouds looked like from the ground.

notice the milky looking sky over northern Minnesota into canada and across the upper great lakes. It is wildfire smoke from canada that continues to plague parts of the United States. This image is courtesy of NOAA. YOu can link to current GOES satellite imagery from our homepage. Click on the GOES link.

Notice the Cool Air Boundary labeled on the satellite imagery. It is identified by the narrow line of cumulus clouds that has formed along its leading edge. Compare the shape and location of the cloud line with the trof (that is short for trough line) dashed line on the map from Illinois into Indiana to a weak low center Ontario. The shape on the map does exactly not match the satellite. The satellite gives the best location for the trof line because the data on the map is not spaced close enough together to place the trof exactly. The satellite image gives forecasters a better look at the trof and what is going on along it than the surface map.

If you have practiced your station model plotting or have looked at where the data is plotted around the observation locations on the map you know that the temperature and dew point are plotted to the left of the station location. For example Chicago reports a temperature of 76 and a dew point of 55. The cooler air behind the trof has dew points in the 50s. Ahead of the trof dew points are in the 60s.

The trof line is where the leading edge of cooler drier air shows up on the satellite image as line of cumulus clouds. The satellite provides the best look at where the trof is really located. The surface map shows us the weather observations on the ground - wind, temperature, dew point, cloud cover, pressure and pressure changes. Using both sources of information gives us the best picture of the trof location and weather conditions ahead and behind it.

Scroll down to see the clouds over northeast Iowa.

Map plotted using Digital Atmosphere software from www.weathergraphics.com.

Let’s focus in on the clouds over northeastern Iowa. We see them on the satellite image and now from the ground. The photos below were taken at the same time as the satellite image. These clouds were all above 6,500 feet and below 20,000 feet so their name is prefixed by ‘Alto.’ The clouds are heaped so they are cumulus type clouds. Their name is Altocumulus. Most of them have heaped tops which is the giveaway. Knowing whether to name them Altocumulus takes experience. Over time you will gradually learn the difference between how lower Cumulus look when compare to mid-level Altocumulus. These clouds are tricky because they are large enough to look like a lower cloud but our nearby airport was measuring the clouds above 6,500 ft (above 2000 meters) which puts them in the mid-levels. If you look at Altocumulus clouds in other posts here you will not see many that look this large. Altocumulus castellanus can be this large but part of that is due to how low in the mid-levels they form. Clouds closer to the ground look larger than high clouds.