SKYWARN Storm Spotter Guides Online

This module compiled with information courtesy of the official NOAA Storm Spotters Guide.

SECTION TWO:

As in the other sections, you can click on the glossary image wherever you see it, and the glossary will open in another window. Just close that window when you are ready to continue.

In this section, you will concentrate on identifying the features of storm structure. This is very important to know what the storm is doing, which way it is going, and keeping yourself in a safe position. The best viewing position if ideally to the right of the storm. Most commonly, many of the storms will move from SW to NE. Thus the best viewing position would be southeast of the storm.

This would change somewhat in HP cells, but that will be covered in the Advanced module. Keep in mind, storms have no sense of direction, and do not know which way is north. They can move in any direction, and with the proper knowledge of storm structure and the movement of the storm, you can put yourself in the best viewing position. For our purposes here, we will assume that the storms are moving SW to NE.

In the two images above, we see a side view drawing of a supercell. The direction of movement in both is from left to right. Note that the anvil is blown downstream in the direction of the movement of the storm. This is a key way to identify the general direction of the storm visually. The varies elements of the storm are identified and color coded in the second drawing to make identification easier. Make yourself very familiar with these terms and their location.

Below we see a photo of a supercell storm. Since it is difficult to get the entire storm in one photo, we will have to take a look at different elements of the storm structure in different photos.

In the above picture, we are looking SE at the storm. Movement is from right to left, SW to NE. We are to the NW of the storm. The various elements outlined are color coded as follows:

DARK BLUE area in the upper center/ this is the Backsheared anvil.
PINK area within the dark blue in the upper areas / this is where mammatus clouds are likely to be seen later
ORANGE area on the right side / this is the Flanking Line
YELLOW area in the middle / this is the main updraft area
BLUE box area near the bottom / this is the rain free base
PINK box near the bottom / this is the area to watch for wall cloud and tornado development. Note that this is directly below the main updraft area
DARK GREEN box / this is where large hail would be occurring
LIGHT GREEN box / this is where smaller hail would fall
BLUE box to the left / this is where the heaviest rain would fall. If we could see further to the left we would see the rain getting lighter and lighter.

In this photo from a distance, we can see some of the larger storm features. This storm is moving which way?

You got it, right to left. Remember the direction the anvil is being swept is the general direction of movement of the storm. Features are anvil, the overshooting top, the backsheared anvil, the main updraft region, and in the boxes in the lower part of the storm, we would expect to see the rain-free base, the area of wall cloud/tornado development, the areas of large and smaller hail, and the areas of heavy, moderate and light rain.

Image was submitted by a viewer of this site.

In the above picture, we can see the Mammatus clouds, which appear as lumps on the underside of the anvil of an departing storm. This was taken in San Angelo, Tx. This storm was moving left to right here, with the updraft to the right of this picture.

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