Listed below are the major concepts that you should know when finished with this unit!

Objective 1: Determine various intensities of precipitation using local Nexrad reflectivity images.

Higher reflectivity values indicate heavier precipitation. Values of 60 or higher are often associated with hail.

Objective 2: Determine the movement of precipitation using Doppler velocity images.

Inbound air (precip.) is shown in green, while outbound is shown in red. The image above shows movement from the southeast toward the northwest.

Objective 3: Use Doppler Estimated Precipitation images to determine the amount of rain (and snow...using a 1" - 10" conversion) that has fallen in a given area.

The estimated precipitation images are a good indicator of what locations received the heaviest precipitation, and is useful in determining who may have a flash-flood threat if heavy precipitation were to follow again shortly.

Objective 4: Use the Regional Radar Summaries to determine echo tops, cell movement, storm rotation & hail production, as well as areas placed under SPC watch boxes.

Cloudtops are shown in hundreds of feet, so the highest top in the image above is 45,000'. Storm cell movement is shown by the vectors, and in this case, a rotating storm(supercell) is moving to the northeast at 42 knots. Ohio, Pennsylvania, and West Virginia are under a severe thunderstorm watch in this image as well.

Objective 5: Identify vertical cross-sections and the mode in which the radar takes these images.

Using the Range Height Indicator, a radar operator can stop and take a vertical slice of a storm. Severe thunderstorms often exhibit certain signatures in this vertical cross-section, such as the bounded weak-echo region shown above (which is characteristic of a rotating storm).

Objective 6: Determine the signatures of rotation and strong downburst winds using Doppler velocity images.

Using the same directions (inbound in green, outbound in red) as in Objective 2, it is possible to determine rotation within thunderstorms on a fairly small scale.

Look at the image above from Minnesota: the radar site is shown in the center of the screen at point X. To the southwest of the radar site, note the inbound air (precip.) in bright green adjacent to the outbound air (precip.)...this is a signature of rotation.

Furthermore, strong downburst winds can be inferred from a velocity image, as in the radar image from Tennessee below: note that the radar signature does not indicate rotation, but rather winds moving outward from a central point...this is a signature of a downburst.

Objective 7: Determine relative cloud top heights from visible and infrared satellite imagery, and identify features of thunderstorms using these images.

The general rule in satellite imagery is the brighter white the cloud, the higher the cloud. Beyond this, you will need to learn to identify the bulging updraft regions of thunderstorms, as well as the anvil portion of the storm that spreads out in the upper-level wind field.

Infrared imagery provides information at night, and once again you will need to recognize the color-enhanced cloud tops and thunderstorm structure.

Objective 8: Identify dry and moist areas using water vapor satellite imagery.

Water vapor imagery can provide important insight into the amount of water vapor in the air, which can influence instability, rainfall amounts, the liklihood of flash-flooding, etc. The brightest white areas are clouds, while the shades of grey indicate amounts of water vapor. Very dry air appears dark.