The hazard (tornado, severe thunderstorm, flash flood, etc.) is imminent. The probability of occurrence is extremely high. Warnings are issued based on eyewitness reports or clear signatures from remote sensing devices such as radar and satellite. Lead-time for thunderstorm type events is generally 30 minutes or less. Lead-time for river floods, and winter storms can be 6 to 18 hours or longer.
When severe weather approaches your area, our forecasts become so short term that we are actually "warning" you that a potentially life threatening event is about to happen and to put your protection plan into action. When we issue a warning it means a certain weather phenomena is occurring or imminent.
WARNINGS |
CRITERIA |
TORNADO WARNING | tornado is occurring or imminent |
SEVERE THUNDERSTORM WARNING | thunderstorm winds 58 mph and/or hail ¾ inch are occurring or imminent |
FLASH FLOOD WARNING | short duration (less than 6 hours), intense flooding resulting from torrential rain, dam breaks or ice jams |
FLOOD WARNING | longer, more gradual flooding usually beginning after 6 hours of excessive rainfall or during spring snow run off |
SMALL STREAM FLOOD WARNING | short duration (less than 6 hours), intense flooding resulting from torrential rain |
URBAN FLOOD WARNING | short duration (less than 6 hours), localized intense flooding resulting from torrential rain in city areas which results in damage or closed roads |
BLIZZARD WARNING | winds 35 mph and falling and/or blowing snow reducing visibility to < ¼ mile lasting for 2 hours or longer |
HEAVY SNOW WARNING Snake River Valley below 3000 feet |
4 inches in 12 hrs.... 6 inches in 24 hrs |
HEAVY SNOW WARNING Mountains generally 3000 feet and above |
8 inches in 12 hrs.... 12 inches in 24 hrs |
ICE STORM WARNING | ice storm producing significant and possibly damaging accumulation of ice (usually ¼ inch |
WINTER STORM WARNING | heavy snow with another winter element (wind, freezing rain, wind chill, etc.) |
HIGH WIND WARNING | sustained winds 40 mph for at least 1 hour or any gusts 58 mph or more for any duration which are not associated with thunderstorm activity |
FREEZE WARNING | temperatures at or below 32 degrees over a large area during the growing season |
WIND CHILL WARNING | Wind chills at or below minus 20 degrees F with a wind of 10 mph or greater are expected. |
FROST WARNING | don't issue these |
DUST STORM WARNING | widespread visibilities < 1/4 mile and winds 30 mph or greater |
When meteorologists have determined that conditions appear right for the development of the hazard and the probability of occurrence is usually greater than 60% a weather watch is issued. Watches generally cover larger areas than warnings. In the case of thunderstorms, less than 30% of the watch area may experience the hazard. However, with larger storms such as winter storms, the entire watch area may be affected. Severe thunderstorm and tornado watches are usually issued 1 to 2 hours before the event begins. The Storm Prediction Center in Norman, OK currently issues all Severe Thunderstorm and Tornado Watches. With flash floods, the length of time can be 3 to 12 hours. For river flood and winter storm watches, lead-times are usually 12 to 36 hours or longer.
The NWS issues watches up to 36 hours in advance of potentially hazardous weather, giving you plenty of time to plan ahead and protect yourself and your family. A Watch means conditions are favorable for certain weather phenomena to occur but it is not expected immediately. Go about your normal activities, but be aware of rapidly changing weather conditions and notify school emergency contact points for potential activation later on. A list of various watches appears on the next page.
WATCHES |
CRITERIA |
TORNADO WATCH | conditions are favorable for tornadic development |
SEVERE THUNDERSTORM WATCH | conditions are favorable for the development of thunderstorm winds 58 mph and/or hail ¾ inch |
FLASH FLOOD WATCH | potential for short duration, intense flooding resulting from torrential rain, dam breaks or ice jams |
FLOOD WATCH | potential for longer, more gradual flooding usually beginning after 6 hours of excessive rainfall |
WINTER STORM WATCH | potential for a blizzard, heavy snowfall, ice storm and/or high winds |
WIND CHILL WATCH | potential for wind chill at or below -20°F with a wind of 10 mph or greater |
HIGH WIND WATCH | potential for sustained winds 40 mph and/or gusts 58 mph for any duration which are not associated with thunderstorm activity |
An advisory is issued for weather that is expected to be a disruption to the normal routine and an inconvenience, but it is not expected to be life-threatening. Advisories are issued for 3 to 5 inches of snow, dense fog, minor street flooding, etc. The time frame is similar to that of a warning. A list of various advisories appear below.
ADVISORIES |
CRITERIA |
URBAN AND/OR SMALL STREAM FLOOD ADVISORY | short duration (less than 6 hours), localized flooding resulting from torrential rain in city areas, non-life threatening |
WINTER WEATHER ADVISORY | a combination of winter weather (snow, wind, freezing rain, wind chill, drifting snow) that presents a hazard but does not meet warning criteria |
BLOWING/DRIFTING SNOW ADVISORY | blowing and/or drifting snow which causes reduced visibilities and/or significant travel problems |
SNOW ADVISORY below 3000 feet |
Snow Accumulation 3-5 inches in 12 hrs 5 to 9 in 24 hrs |
SNOW ADVISORY Mountains generally 3000 feet and above |
none issued - |
FREEZING RAIN/DRIZZLE ADVISORY | freezing rain event resulting in significant inconvenience and that could lead to life- threatening situations if caution is not exercised |
WIND CHILL ADVISORY | wind chill forecast of minus 35 degrees F or lower with a 10 mph or greater wind speed |
WIND ADVISORY | sustained winds 30 to 39 mph lasting for one hour or longer and/or wind gusts 45 to 57 mph for any duration which are not associated with thunderstorm activity |
DENSE FOG ADVISORY | widespread visibilities reduced to less than ¼ mile because of fog |
BLOWING DUST ADVISORY | widespread visibilities reduced to less than ¼ mile because of dust or sand |
VOLCANIC ASH ADVISORY | whenever it occurs |
Statements are issued to update current weather situations or highlight significant changes to come. Statements are also used to explain why watches, advisories, or warnings have been issued. Four special types of statements include:
General weather and hydrologic information issued daily (times given are listed in Pacific time).
NOTE: All of the above (Watches, Warnings, Statements, Advisories, Forecasts) are broadcast continuously on the NOAA Weather Radio.
However, the NWS Forecast Offices also issue other forecasts, such as Aviation Terminal Forecasts and Fire Weather Forecasts (for prescribed burning operations or wildfires). These products are not announced on the Weather Radio.
31 Northeast Blue Mountains | 37 Northeast Washington Mountains |
32 Lower Asotin and Garfield Counties | 38 Okanogan Highlands |
33 Washington Palouse | 41 Wenatchee Area |
34 Moses Lake Area | 42 East Slopes of Northern Cascades |
35 Upper Columbia Basin | 43 Okanogan Valley |
36 Spokane Area | 44 Waterville Plateau |
1 Northern Panhandle Mountains | 4 Central Panhandle Mountains |
2 Coeur d'Alene Area | 26 Lewiston Area |
3 Idaho Palouse | 27 Camas Prairie |