12/4/2023 0 Comments Chicago weather tornado warningSynoptic scale gradient winds (those not associated with thunderstorms) or mesoscale winds associated with wake lows are expected to reach speeds of 40 mph or greater, sustained for at least one hour, or 58 mph or greater gusts. Widespread temperatures below freezing when during the growing season are expected. For NWS criteria across the area, click here.Ĭhicago/Cook County: Three consecutive days with a peak heat index expected to reach 100-105° or two consecutive days with a forecast peak heat index 105-110° or one day with an expected peak heat index forecast at 110° or higher.Įlsewhere: Maximum heat index is expected to reach 110° or greater and a minimum heat index of 75° or greater for at least 48 hours. Widespread wind chill values around -30° or colder. Ice accumulations of a quarter inch or more are expected. These are not issued when Winter Storm or Blizzard Warnings are in effect. considerably smaller in space and time than Winter Storm Warnings) and issued for localized, intense areas of snow/wind expected to cause sharply reduced visibility of 1/4 mile or less often with sub-freezing road temperatures. These are short-fused, smaller warnings (i.e. A warning may also be issued if conditions will be approaching blizzard criteria and/or have significant impacts, even if snowfall amounts are not expected to reach the criteria above. Snow amounts of 6 inches or more in 12 hours, or 8 inches or more in 24 hours, or heavy sleet accumulations of one half inch or greater are expected. These may or may not be accompanied by wind or other phenomena. Wind speeds of 35 mph or greater, considerable falling or blowing snow, and visibilities frequently below a quarter mile are expected to prevail for three hours or more. An additional tag of "Expected Rainfall Rate" will be included when warning forecasters have enough confidence to include expected rainfall rates with the storm. The flash flood tag will be either "Radar Indicated", "Gauge Indicated", or "Observed", with the last of those three giving confirmation that flash flooding has been reported with the storm. The damage threat tag is for progressively worse expected damage and are "Considerable" and "Catastrophic". These warnings are impact-based meaning they include a flash flood tag and at times a damage threat tag at the bottom. A warning may also be issued if a dam break has occurred. Long duration areal or river flooding is occurring or is imminent, which may result from excessive rainfall, rapid snow melt, ice jams on rivers or other similar causes.Įxcessive rainfall producing thunderstorms have developed, leading to short duration flash flooding. An additional tag of "Tornado Possible" will be included when warning forecasters suspect a tornado is possible in addition to the damaging winds and/or hail. The wind and/or hail tag is either "Radar Indicated" or "Observed", with the latter giving confirmation that severe weather has been reported with the storm. The damage threat tag is for progressively worse expected damage and are "Considerable" and "Destructive". These warnings are impact-based meaning they include wind and/or hail tags and at times a damage threat tag at the bottom. The tornado tag is either "Radar Indicated" or "Observed", with the latter giving confirmation a tornado has been reported with the storm. The tornado damage threat tag is for progressively worse expected damage and are "Considerable" and "Catastrophic".Ī severe thunderstorm or a line of severe thunderstorms capable of producing hail greater than one inch in diameter and/or 50 knot (58 mph) wind speeds. These warnings are impact-based meaning they include a tornado tag and a tornado damage threat tag at the bottom of the warning. A severe thunderstorm has radar indications of intense low level rotation in the presence of atmospheric conditions conducive to tornado development, and/or is producing a tornado based on reports.
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