Winter Weather Watches

Criteria / Definition

Winter Storm Watch

Conditions are favorable for hazardous winter weather conditions including heavy snow, blizzard conditions, or significant accumulations of freezing rain or sleet in the next 12 to 48 hours.

Blizzard Watch

Conditions are favorable for blizzard conditions in the next 12 to 48 hours.

Wind Chill Watch

Conditions are favorable for dangerous wind chills in the next 12 to 48 hours.

Winter Weather Warnings

Criteria / Definition

Heavy Snow Warning

6 inches or more in 12 hours or 8 inches or more in 24 hours with no blowing snow and sustained winds
< 20 mph.

Winter Storm Warning

Heavy Snow Warning criteria for snow accumulation and sustained winds or frequent gusts 25 to 34 mph with reduced visibility to ≤ ¼ mile for 3 hours or more.

Blizzard Warning

Sustained or frequent gusts of 35 mph or more, frequent visibilities of  ≤ ¼ mile, falling and/or blowing snow for 3 hours or more.

Wind Chill Warning

Wind chills of ≤ -40 degrees with winds of ≥ 10 mph

Winter Weather Advisories

Criteria / Definition

Snow Advisory

2 to 5 inches in 12 hours.

Blowing Snow Advisory

Wind driven snow that occasionally reduces visibilities to ≤ ¼ mile.

Snow and Blowing

Snow Advisory

Snow advisory and blowing snow advisory criteria together.

Winter Weather Advisory

More than one predominant hazard (i.e. Snow and Freezing Rain, Sleet and Freezing Rain, etc) meeting or exceeding 12 and/or 24 hour advisory criteria for at least one of the precipitation elements, but remaining below warning criteria.

Wind Chill Advisory

Wind chills of -20 degrees to -39 degrees with winds of ≥ 10 mph

Freezing Rain Advisory

Glazing of freezing drizzle or freezing rain with accumulations of less than ¼ inch.

Flooding Products

Criteria / Definition

Flood Watch

The potential exists for a river to exceed flood stage in the next 12 to 72 hours.   (Issued for the Milk, Missouri, Poplar and Yellowstone Rivers)

Flash Flood Watch

The potential exists for heavy rains to create flash flooding in the next 6 to 24 hours.

Flood Warning

The river is expected to exceed flood stage in the next 48 hours.  Loss of life or property is possible with this type of event. (Issued for the Milk, Missouri, Poplar, and Yellowstone Rivers)

Flash Flood Warning

Flash Flood conditions are occurring or are expected to occur in the next 6 hours.   Loss of life or property is possible with this type of event.

Urban/Small Stream Flood Advisory

This is used for minor flooding in towns, or small creeks, or areas where roads may have running water over them.

Urban/Small Stream Flood Warnings

This is used for significant flooding within a town, or on creeks and streams that are tributaries to mainstem rivers.   Loss of life or property is possible during this type of event.

Flood or River Statement

This is just a statement that gives you information on a creek or river that is rising, but isn’t expected to reach flood stage. 

Summer Watches

Criteria / Definition

Severe Thunderstorm Watch

Conditions are favorable for the development of severe thunderstorms in and close to the watch area within the next 12 hours.

Tornado Watch

Conditions are favorable for the development of severe thunderstorms producing tornadoes in and close to the watch area in the next 12 hours.

Summer Warnings

Criteria / Definition

Severe Thunderstorm Warning

Hail ¾" (penny size) diameter or larger or wind gusts of 58 mph or greater.

Tornado Warning

Radar or satellite indication and/or reliable spotter reports of a tornado.

Wind and Fog Advisories

Criteria / Definition

Wind Advisory

Livingston Area / Beartooth Foothills Only – Sustained winds ≥ 40 mph for at least 2 hours or any gust between 58 mph to 74 mph.

Dense Fog Advisory

Visibility ≤ ¼ mile for 3 hours more.

Lake Wind Advisory

Fort Peck Lake only – Winds sustained at 20 mph or higher for 3 hours or more, or any gusts to 30 mph or higher.

High Wind Watch / Warning

Criteria / Definition

High Wind Watch

Conditions are favorable for high winds in and close to the watch area in the next 12 to 48 hours.

High Wind Warning

Sustained winds ≥ 40 mph for at least 2 hours or any gust ≥ 58 mph.

Fire Watch / Red Flag Warning

Criteria / Definition

Fire Weather Watch

Conditions are favorable for red flag conditions in and close to the watch area in the next 12 to 48 hours.

Red Flag Warning

Fire Danger Very High or Extreme, Sustained winds >= 20 mph and relative humidity <= 20%, scattered dry thunderstorms, increased tstm activity after a prolonged dry period, abrupt change in wind speed and direction that may affect the area.