What are some ways i can detect rotation within a severe storm?

Question

What are some ways i can detect rotation within a severe storm?

Answer 1

If the storm front is approaching your location you may notice dark lines forming in the cloud bank, and surface winds in your area pick up, (possibly bringing in moist air, or even fog, from a nearby large body of water, and funneling that up into the approaching storm, which is intaking moisture with the associated latent energy).  The lower parts of the storm front will show the effects of wind shear rippling the cloud bank at the base, and the lines in the cloud bank will begin to twist and break up, and the approaching cloud bank may take on strange dark colours.  

If viewed from the side, you may notice small clouds sailing around the larger cloud, like small ships circling a large iceberg, and of course you may see lightning flashes, and dark areas of rain pouring down, and possibly lighter streaks of hail falling as well.  The top of the cloud may be surrounded by a veil of ice, and the rising plume of the cloud top may be advancing upward through the ice layer.

Funnel clouds may be hanging from an anvil-shaped or plow-shaped cloud formation near the back of the storm cloud, (viewed from the side), and if there funnels reach the ground tornadoes or various strengths will occur.

If you are close to the touch down of a funnel you will notice trees and other flexible objects experiencing rapid shifts in wind direction, so some trees will appear to whip back and forth, or twist upwards.  Of course at this point it is not safe to be watching this activity and you should already be seeking shelter in a closed and secure structure.

I am not an expert on toradoes, but I have watched many storms and I would say that storms that may produce tornadic activity are much easier to figure out when viewed from the side than if they are coming at you straight on.

The rapid intake of local air being sucked up into an approaching storm is a key indicator that something violent is about to happen in your local atmosphere, and this is particularly true if you have a cold lake near your location in the path of the approaching storm.  When those local intake winds produce wind shear that is a time when I begin to take cover.

I hope some of this layman logic, (without the use of doppler, storm radio warnings, etc....), will help in answering your question, and hopefully enable you to make good decisions on the ground when you are experiencing severe weather.

Answer 2

Visually you can actually see the rotation before a tornado is happening.  You'll notice the entire cloud seems to have rotation in a supercell that is becoming tornadic.

With doppler radar:

Doppler radar can detect velocities in a cloud when there are droplets (which is in any cumulonimbus cloud, the ones that actually can rotate in association with a developing tornado).  Radar can only pick up inbound velocity and outbound velocity (you can't see velocity going to the right or left with respect to the direction the radar is seeing the storm).  Rotation will look like strong inbound velocities right next to strong outbound velocities.  This is part of the algorithm the weather service will use to identify a storm with a 'TVS,' or tornado vortex signature.

In reflectivity (simply the amount of radar energy that is coming back to the radar detector) you can also infer rotation.  This will look like a hook in the reflectivity field.  It looks like a hook because the droplets/rain wraps around the vortex.

Answer 3

Radar: doppler wind display.

Radar: a sequence of reflectivity scans displayed in a viewer that loops the images.

Observations: surface or aircraft observations of wind speed and direction in the vicinity of the storm.

Satellite imagery: see radar reflectivity above.