Watch/Warning Criteria by NWS WFO

This is a section in where you can view the criteria for advisories, watches, and warnings issued by the NWS offices.

• Winter Storm Watch - Issued within 12 - 48 hours of a winter event with at least a 50% chance of occurring.
• Blizzard Watch - Issued 12 - 48 hours before a possible blizzard with the probability of occurring at 50% or greater. A blizzard is defined as frequent wind gusts exceeding 35mph with heavy snowfall reducing visibility to less than 1/4 mile for at least 3 hours.
• Winter Weather Advisory - Issued within 36 hours of a winter event with at least an 80% chance of occurring, but when the threat doesn't exceed those of a winter storm warning.
• Winter Storm Warning - Issued within 36 hours of a storm for snow amounts of 2“+, 1/2”+ of sleet, and or 1/4“+ freezing rain.
• Blizzard Warning - Issued up to 36 hours before a potential blizzard with the probability of occurring at 80% or greater. A blizzard is defined as frequent wind gusts exceeding 35mph with heavy snowfall reducing visibility to less than 1/4 mile for at least 3 hours.

• Freezing Rain Advisory - Issued within 36 hours of an ice event that has at least an 80% chance of occurring, but in which the threat does not exceed warning criteria.
• Ice Storm Warning - Issued within 36 hours of an ice event that has at least an 80% chance of occurring, in which 1/4”+ of freezing rain is possible.

• Wind Chill Watch - Issued 12 - 48 hours before a time in which there is a 50% or greater chance where the wind chill could be -10F or below.
• Wind Chill Advisory - Issued within 36 hours before a time in which there is an 80% or greater chance of where the wind chil could be between 5F and -10F.
• Wind Chill Warning - Issued within 36 hours before a time in which there is an 80% or greater chance of where the wind chil could be -10F or below.

The JAX main page links here - http://www.weather.gov/safety/ - Apparently JAX does not publish its own criteria.

SEVERE THUNDERSTORM WARNING Thunderstorm winds 58 mph (50 kts) and/or hail 1 inch (2.5 cm) or greater

TORNADO WARNING A tornado has been spotted or detected on radar

FLASH FLOOD WARNING Short duration (usually less than six hours), flash flooding resulting from storms with rainfall rates of 1 to 2 inches per hour or greater. Also issued when a dam has failed or when a dam failure is imminent.

FLOOD WARNING (AREAL/COUNTY) Long duration (slow to evolve), flooding resulting from steady stratiform rain with rates typically less than 1 inch per hour. Most common during long duration spring rains resulting in widespread flooding.

RIVER FLOOD WARNING River flooding is occurring or is forecast for a point. Normally issued when flooding is forecast within 24 hours based on accumulated rainfall, but may also be issued when there is a high confidence in a heavy rain event.

HIGH WIND WARNING Non-convective sustained wind speeds 40 mph (35 kt) and greater and/or frequent wind gusts 50 mph (43 kt) and greater or any winds gusts 57 mph (50 kt) and greater

WINTER STORM WARNING Snow accumulations 3 inches or greater in 12 hours (4 inches or more in 24 hours); Freezing rain accumulations ¼ inch (6 mm) or greater; Sleet accumulations ½ inch (13 mm)or more. Issued when there is at least a 60% forecast confidence of any one of the three criteria being met.

BLIZZARD WARNING Winds 35 mph (30 kts) AND falling and/or blowing snow reducing visibility to less than ¼ mile (1.2 km) for at least three hours

ICE STORM WARNING Freezing rain accumulations ¼ inch (6 mm) or greater resulting in significant, widespread power outages, tree damage and dangerous travel. Issued only in those rare instances where just heavy freezing rain is expected and there will be no “mixed bag” precipitation meaning no snow, sleet or rain.

WIND CHILL WARNING Wind chill -15ºF or lower with wind speeds 10 mph (9 kt) or greater

FREEZE WARNING When temperatures will be at or below 32ºF over a large area for a significant time during the growing season

EXCESSIVE HEAT WARNING Heat Index of 110ºF or greater for any duration

RED FLAG / FIRE WEATHER Dangerous fire behavior expected within 12-24 hours based on weather conditions and dry fuels. Generally wind gusts 20 mph (17 kt) or greater, minimum humidity 25% or lower and dry fuels. Coordinated with the NC Division of Forestry.

FLOOD ADVISORY Localized flooding resulting from heavy rain. Water may start to threaten homes and businesses, and minor flooding of roads is possible

WINTER WEATHER ADVISORY Snow accumulations 1-3 inches; Any freezing rain accumulations less than ¼ inch; Any sleet accumulations less than ½ inch. Winter Weather Advisories are issued in any one of the three criteria are forecast to be met

WIND CHILL ADVISORY 0ºF to -14ºF with wind speeds 10 mph (9 kt) or greater

FROST ADVISORY When frost is expected during the growing season

WIND ADVISORY Non-convective sustained wind speeds 31-39 mph (27-34 kt); frequent wind gusts 40-45 mph (35-39 kt); any wind gusts 46-57 mph (40-50 kt)

HEAT ADVISORY Heat Index of 105ºF to 109ºF for 3 hours or more. Can also be issued for lower values 100ºF to 104ºF for heat lasting several consecutive days

DENSE FOG ADVISORY Fog reducing visibilities to a ¼ mile (0.4 km) or less

DENSE SMOKE ADVISORY Smoke reducing visibilities to a ¼ mile (0.4 km) or less and/or smoke expected to cause travel hazards. Could be localized or widespread

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