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Excessive Heat Warning
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Extreme heat index making it feel like above 110 °F (43 °C) with a minimum above 80 °F (27 °C).
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Flash Flood Warning
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Signifies a dangerous situation where rapid flooding of small rivers, streams, creaks, or urban areas are imminent or already occurring. Very heavy rain that falls in a short time period can lead to flash flooding, depending on local terrain, ground cover, degree of urbanization, degree of man-made changes to river banks, and initial ground or river
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High Wind Warning
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Sustained winds of 40 mph (65 km/h) or greater for a duration of one hour or longer or gusts to 58 mph (93 km/h) or greater.
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Severe Thunderstorm Warning
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Issued when a thunderstorm produces hail 3/4 inch (20 mm) or larger in diameter and/or winds which equal or exceed 58 mph (93 km/h). Severe thunderstorms can result in the loss of life and/or property. Information in this warning includes: where the storm is, what towns will be affected, and the primary threat associated with the storm.
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Tornado Warning
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Tornado is indicated by radar or sighted by storm spotters. The warning will include where the tornado is and what towns will be in its path. (Also automatically indicates a Severe Thunderstorm Warning)
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Watches
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A watch is used when the risk of a hazardous weather has increased significantly, but its occurrence, location or timing is still uncertain. It is intended to provide enough lead time so those who need to set their plans in motion can do so. A watch means that hazardous weather is possible. People should have a plan of action in case a storm threatens and they should listen for later information and possible warnings especially when planning travel or outdoor activities. NWS may activate weather spotters in areas affected by watches to help them better track and analyze the event.
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Severe Thunderstorm Watch
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Conditions are favorable for the development of severe thunderstorms in and close to the watch area. Watches are usually in effect for several hours, with 6 hours being the most common.
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Tornado Watch
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Conditions are favorable for the development of severe thunderstorms producing tornadoes in and close to the watch area. Watches are usually in effect for several hours, with 6 hours being the most common. (Also automatically indicates a Severe Thunderstorm Watch)
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Advisories
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An advisory is issued when hazardous weather is occurring, imminent or likely to occur. Advisories are for less serious conditions than warnings that cause significant inconvenience and if caution is not exercised, could lead to situations that may threaten life or property. NWS may activate weather spotters in areas affected by advisories to help them better track and analyze the event.
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Heat Advisory
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Maximum heat index of 105 to 110 °F (40 to 43 °C) with a minimum of 75 °F (24 °C) for two or more consecutive days.
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Hail Diameter Size
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Size
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Compared To
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1/4 in (6 mm)
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Pea Size
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1/2 in (13 mm)
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Small Marble Size
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3/4 in (20 mm)
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(Severe Criteria) Dime/Penny/Large Marble Size
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7/8 in (22 mm)
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US 5 Cent Coin Size
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1 in (25 mm)
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US 25 Cent Coin Size
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1 1/4 in (32 mm)
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US 50 Cent Coin Size
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1 1/2 in (37 mm)
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Walnut or Ping Pong Ball Size
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1 3/4 in (43 mm)
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Golf Ball Size
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2 in (50 m)
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Hen Egg Size
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2 1/2 in (62 mm)
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Tennis Ball Size
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2 3/4 in (70 mm)
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Baseball Size
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3 in (75 mm)
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Teacup Size
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4 in (100 mm)
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Grapefruit Size
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4 1/2 in (115 mm)
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Softball Size
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Wind Scale
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Wind Speed
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Result
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25 to 31 mph
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Large branches in motion; whistling in telephone wires
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32 to 38 mph
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Whole trees in motion; inconvenience felt walking against wind.
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39 to 54 mph
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Twigs break off trees; wind generally impedes progress.
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55 to 73 mph
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Damage to chimneys and TV antennas; Pushes over shallow-rooted trees.
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74 to 112 mps
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Peels surfaces off roofs; windows broken; mobile homes overturned; moving cars pushed off road.
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113 to 157 mph
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Roofs torn off houses; cars lifted off ground.
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