– Ring or arc that seem to encircle the sun or moon. Caused by the refraction of light through the ice crystals in cirrus clouds.

– freeze where vegetation is killed and the ground surface is frozen solid.

Fine dry or wet dust or salt particles in the air that reduce visibility.

– In the Inland Northwest, mountains above 3000 feet – 8 to 12 inches in 12 hours or 12-18 inches or more in 24 hours. For the valleys and Basin below 3000 feet – 4 inches in 12 hours and 6 inches in 24 hours.

– The HI is the temperature the body feels when the heat and humidity are combined.

– The thermal induced surface low pressure trough that develops during the warm season in the lee of the Cascades.

– Streamwise vorticity available for ingestion into a thunderstorm. Higher values are favorable for a rotating updraft (greater than 400). A measure of low level wind shear, normally within the lowest 3 km of the atmosphere, relative to the movement of a thunderstorm (thus referred to as 0-3 km Storm Relative Helicity). This gives forecasters an indication of an environment that is favorable for supporting the development of thunderstorms with rotating updrafts, a precursor to supercell thunderstorms (the most violent of severe storms) and tornado development. Values of helicity greater than +150 are considered significant; however, like CAPE values, there is no magic value of (positive) helicity under which rotating thunderstorms will not develop. Helicity is only an index to determining thunderstorm rotation potential.

– Hydrologist In Charge.