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New England Weather Alerts: What it Takes to Get Every Alert in the Region

Updated: Dec 15, 2023

To get a watch (severe thunderstorm watch, winter storm watch, flood watch, etc.), there has to be at least a 50% chance that the weather will meet warning criteria, usually within 1-3 days. The watch is upgraded to a warning when the chances of meeting the criteria reach 80%, usually within 1 day or less.



All criteria listed below come straight from the National Weather Service


SEVERE WEATHER


Severe Thunderstorm Warning:

-Wind gusts at least 58mph, and/or

-Hail greater than 1 inch in diameter, and/or

-Tornado


Tornado Warning:

-Radar supports the possibility of a tornado, or

-A storm spotter confirms a tornado is on the ground


Tornado Emergency:

-A strong, life-threatening tornado is confirmed on the ground causing catastrophic

damage


HEAT


Heat Advisory

-Heat index values of 95-99° for at least 2 hours over 2 consecutive days, or

-Heat index values of 100-104° for at least 2 hours over 1 day


Excessive Heat Warning

-Heat index values of 105+° for at least 2 hours


Heat Wave

-A heat wave is declared when a location reaches 90+° for at least 3 consecutive days



COLD


Wind Chill Advisory

-For southern New England: Wind chills values of -15 to -24° for at least 3 hours

-For northern New England: Wind chill values of -20 to -29° for at least 3 hours


Wind Chill Warning

-For southern New England: Wind chill values at or below -25° for at least 3 hours

-For northern New England: Wind chill values at or below -30° for at least 3 hours


Frost Advisory

-Overnight low temperatures to drop to 33-36° during growing season


Freeze Warning

-Overnight low temperatures to drop to 32° or lower during growing season


WINTER


Winter Weather Advisory

-Snow or sleet accumulation average of 3 inches for southern New England or 4 inches

for northern New England in 12 hours

-Sustained winds (or frequent gusts) of at least 25mph accompanied by falling or

blowing snow reducing visibility

-Any accumulation of freezing rain on roadways, and/or

-Widespread black ice


Winter Storm Warning

-Snow or sleet accumulations average of 6 inches or more in 12 hours, or

-Snow or sleet accumulations average of 8 inches in southern New England or 9 inches

in northern New England in 24 hours


Blizzard Warning

-Sustained winds of at least 35mph and considerable falling or blowing snow that

reduces visibility to less than a quarter of a mile for at least 3 consecutive hours


Ice Storm Warning

-Half an inch or more of ice accumulation


Snow Squall Warning

-Short-lived burst of very heavy snowfall over a small area that causes sudden whiteout

conditions



FLOOD


Flood Advisory

-Expected overflow or inundation by water which does not threaten life or property


Flood Warning

-Expected overflow or inundation by water which causes damage and/or a threat to life


River Flood Warning

-Water level at river forecast point is expected to reach flood stage


Flash Flood Warning

-Rapid flow of high water into a normally dry area, or

-Rapid water level rise on a stream or creek, or

-Dam or levee failure, or

-Release from an ice jam causing rapid rise in a stream, creek or river


Flash Flood Emergency

-Extremely heavy rain causing severe threat to life and catastrophic damage


Coastal Flood Advisory

-Minor coastal flooding/splashover expected


Coastal Flood Warning

-Widespread moderate to major coastal flooding expected that is expected to damage

property and threaten life


WIND


Wind Advisory

-Sustained winds of 31-39mph for at least 1 hour, or

-Gusts of 46-57mph


High Wind Warning

-Sustained winds of 40mph or more for at least 1 hour, or

-Gusts higher than 57mph


Extreme Wind Warning

-Sustained winds of 111mph or more, usually signifying the approach of an eyewall of a

major hurricane


TROPICAL


Tropical Storm Warning

-Sustained winds of 39-73mph associated with a tropical storm expected within 36

hours


Hurricane Warning

-Sustained winds of 74mph or more associated with a hurricane expected within 36

hours


Storm Surge Warning

-Danger of life-threatening inundation from rising coastal waters moving inland from

shoreline within 36 hours associated with tropical or post-tropical systems



FIRE


Red Flag Warning

-Dry fuels combined with 1 or more of the following weather conditions:

-Sustained winds or frequent gusts of 25mph or more

-Relative humidity at or below 30%

-Rainfall amounts for the previous 5 days less than a quarter of an inch

-Lightning

-Significant dry frontal passage

-Dry thunderstorms


FOG/SMOKE


Dense Fog Advisory

-Widespread visibility reduced to less than a quarter of a mile for at least 3 hours


Freezing Fog Advisory

-Very light ice accumulations from fog at or below freezing


Dense Smoke Advisory

-Smoke reducing visibility to less than a quarter of a mile


Air Quality Alert

-Air quality is expected to drop below healthy levels from pollution or smoke


Air Stagnation Advisory

-Atmospheric conditions stable enough to cause pollutants to accumulate in a given

area



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