Flash Flood Warning

• Life or property-threatening, short-term flooding is imminent or occurring.  This can include flooding due to heavy rainfall or due to a dam or levee break.

Flood Warning

• Flooding due to potentially damaging river level rises,
• OR overland flooding that is expected to persist for many hours.

Special Weather Statement

• Heavy rainfall that is not expected to cause hazardous travel conditions but is not expected to cause flooding.

See NWSI 10-922 WFO Hydrologic Products Specification for additional information.

• Watches are issued when forecaster confidence in meeting criteria reaches 50% and are typically issued in the 12 to 72 hour time frame before the onset of wintry conditions.
• Warnings/Advisories are issued when forecaster confidence in meeting criteria reaches 80% and are typically issued within 24 hours of the onset of wintry conditions.
• Criteria can be adjusted based on expected impacts. 

Blizzard Warning

• Sustained wind or frequent gusts of 35 mph or higher,
• AND visibility less than 1/4 mile in snow and/or blowing snow for 3 hours or longer.

Ice Storm Warning

• Damaging ice accumulations of 1/4" or more.

Winter Storm Watch/Warning

• Snowfall of 4-6" or more, event-driven up to a 48-hour period.
• OR sleet accumulation of 1/2" or more in 24 hours.

Snow Squall Warning

• Snow squalls reducing the visibility to 1/4 mile or less in snow with sub-freezing ambient road temperatures
• OR plunging temperatures behind an arctic front sufficient to produce flash freezes, along with a significant reduction in visibility from falling and/or blowing snow.

Winter Weather Advisory

• Snow, blowing snow, ice, sleet, or a combination of these wintry elements is expected to cause winter driving conditions and difficult travel.

Extreme Cold Watch/Warning and Cold Weather Advisory

• Temperature and/or wind chills at or below the thresholds below.

Special Weather Statement

• Black ice,
• OR short-duration heavy snow bands/squalls.

See NWSI 10-513 WFO Winter Weather Products Specifications for additional information.

High Wind Warning

• Sustained non-thunderstorm wind speeds of at least 40 mph for an hour or more,
• OR non-thunderstorm wind gusts of at least 58 mph regardless of duration.

Wind Advisory

• Sustained non-thunderstorm wind speeds between 30 and 39 mph for at least one hour,
• OR non-thunderstorm wind gusts of 46 to 57 mph for any duration.

Freeze Warning

• Widespread temperatures are forecast to be 32ºF or below for 2 hours or more during the growing season.

Frost Advisory

• Widespread frost during the growing season.

Excessive Heat Warning

• Issued when the heat index is expected to reach around 105ºF or higher for a period of at least 2 hours.
• A warning would also be appropriate if heat advisory criteria are expected to be reached for 4 consecutive days.

Heat Advisory

• Issued for heat index of equal to 100ºF and less than 105ºF for a period of at least 2 hours.

Dense Fog Advisory

• Widespread visibility 1/4 mile or less due to dense fog.

Dense Smoke Advisory

• Widespread visibility 1/4 mile or less due to dense smoke.

Dust Storm Warning

• Widespread visibility 1/4 mile or less due to blowing dust.

Blowing Dust Advisory

• Widespread visibility of between 1/4 mile and 1 mile.

Special Weather Statement

• Heat indices or wind chill values near "advisory" level for an hour or two,
• OR local areas of dense fog, dense smoke or other hazards that are below advisory criteria.

See NWSI 10-515 WFO Non-Precipitation Weather Products Specification for additional information.

Fire Weather Watch (typically issued 24 to 72 hours out) / Red Flag Warning (typically issued within 24 hours)

• West Virginia
  • Sustained 20-foot wind speeds of 15 mph or greater,
  • AND minimum relative humidity of 25% or less,
  • AND 10-hour fuel moisture values of 8% or less.
• Ohio
  • Sustained 20-foot wind speeds or gusts of 15 mph or greater,
  • AND minimum relative humidity of 25% or less,
  • AND 10-hour fuel moisture values of 8% or less.
  • The above criteria must be met for at least 2 consecutive hours.
• Kentucky
  • Sustained 20-foot wind speeds of 15 mph or greater,
  • AND minimum relative humidity of 25% or less,
  • AND 10-hour fuel moisture values of 8% or less.
• Virginia
  • Sustained 20-foot wind speeds of 20 mph or greater,
  • AND minimum relative humidity of 30% or less,
  • AND 10-hour fuel moisture values of 7% or less.

See NWSI 10-401 Fire Weather Services Product Specification for additional information.