Storm Corridors

The storm corridors can be viewed by clicking the Storm Corridors layer within the Weather Layers. Storm corridors depict the area which the storm cell is expected to impact over the next half hour. The corridors are color-coded based on the type of activity detected in the storm cell by NEXRAD. A flashing corridor means a TVS has been detected.

White

Heavy Rain

Intense precipitation, strong wind and/or small hail has been detected.

Yellow

Severe Hail

An event having at least a 25% probability of severe hail with a diameter of 1" (2.5 cm) or greater has been detected. Note: The NWS has recently changed the definition of Severe Hail from .75" to 1" in diameter.

Orange

Dangerous T-Storm

A strong thunderstorm with a mesocyclone (rotation aloft) having an index of 1 or greater has been detected.

Red

Possible Tornado

A thunderstorm with a tornadic vortex signature (TVS) has been detected. Corridors depicting a TVS will flash.

Corridors are not available at the two widest zoom levels. Additional information is available by clicking the Get Details icon and hovering over the displayed corridor.

Get Details

Storm Activity

Detected Activity

Definition

Hail

The probability of hail and/or severe hail and the maximum size expected. Severe hail is defined as hail with a diameter of 1" (2.5 cm) or greater.

Mesocyclone

Rotation detected at multiple levels in a storm and the stringent wind and wind shear criteria are met. Strength is categorized using an index of 1 - 6+.

Tornadic Vortex Signature (TVS)

Indication of a possible tornado. Strong wind shear has been detected in a very small area and is usually associated with a potential tornadic circulation within a thunderstorm.

Mesocyclone Index

The following radar reported index value representing the strength of a mesocyclone signature is used within storm corridors.

Value

Descriptor

Definition

0

None

No mesocyclone

1 - 2

Weak

Weak mesocyclone detected

3 - 5

MDT

Moderate mesocyclone detected

6+

Strong

Strong mesocyclone detected

255

Error Condition

Error condition

Corridor Defaults

Full Length

30 minute forecast period

Half Length

15 minutes (depicted as dashed line)

Width

One mile (1.6 km)

Deviation Angle

Five degrees