As I write this my area of Maine is under a winter storm watch. Now is the time to ask yourself are you ready for the storm? Do you sufficient food, water, candles and other supplies on hand? With that in mind todays post is about the definitions of some common weather terms used by The National Weather Service as an aid in helping you to plan. Click the Weather definitions link to download a copy of the file.
Definitions of Winter Weather Terms used by the National Weather Service
The National Weather Service uses several terms to tell you exactly what kind of weather to expect. These definitions apply for the eastern regions of the United States. Specific definitions for other regions may be found at www.noaa.gov.
1) WINTER STORM OUTLOOK
This is a statement issued when there is a chance of a major winter storms from 3 to 5 days in the future. This is meant to assist people with their long-range plans. However, since the outlook is issued so far in advance, the accuracy of the prediction may be limited.
2) WINTER STORM WATCH
This means there may be hazardous winter weather due to various elements such as heavy snow, sleet, or ice accumulation from freezing rain. In our region, heavy snow means 7 inches or more of accumulation in 24 hours or less. A “WATCH” is a long-range prediction. They are issued at least 12 hours before the hazardous winter weather is expected to begin. When the storm becomes imminent, or has a high probability of occurring, the watch will be upgraded to a “WARNING”.
3) WINTER STORM WARNING FOR HEAVY SNOW
Seven inches or more of snow will fall within a 24 hour period.
4) WINTER STORM WARNING FOR SEVERE ICING
Heavy accumulation of ice due to freezing rain will down trees and power lines. Electricity, or telephone communications, may be out for a long period of time. Roads may become impassable for most vehicles.
5) BLIZZARD WARNING
This is issued for a combination of strong winds averaging or frequently gusting to, or above, 35 miles an hour and very low visibility due to blowing or falling snow. These are the most dangerous winter storms and can be especially severe when combined with temperatures below 10 degrees.
6) WINTER STORM WARNING
This is issued when a dangerous combination of heavy snow, with sleet and/or freezing rain, will occur or has a high probability of occurring within the next 12 hours.
7) HIGH WIND WARNING
This means the expected winds will average 40 miles an hour or more for at least 1 hour or winds gusts will be greater than 58 miles an hour. Trees and power lines can be blown down. A High Wind Warning may be preceded by a HIGH WIND WATCH if the strong winds are not expected to occur for at least 12 hours.
8) WIND CHILL WARNING
This means life threatening cold with wind chill temperatures computed to be -40 degrees or less for at least 3 hours. Exposure to this combination of strong winds and low temperatures without protective clothing will quickly lead to frostbite and/or hypothermia. Longer exposures can be fatal.
9) WINTER WEATHER ADVISORY FOR SNOW
This is issued for snowfall greater than 4 (but less than 7) inches in a 24 hour period. The snowfall is usually expected to begin within the next 12 hours.
10) BLOWING SNOW ADVISORY
This is issued when the visibility will be significantly reduced, or when the roads become snow-covered over a large area.
11) WIND CHILL ADVISORY
This is issued for cold temperatures and winds, with wind chill temperatures computed to be -25 degrees or less for at least 3 hours. Exposure to this combination of strong winds and low temperatures without protective clothing can lead to frostbite and/or hypothermia, prolonged exposure may be fatal.
12) WINTER WEATHER ADVISORY
This is issued for a combination of snow, sleet, and/or freezing rain. Advisories, in general, are issued for weather conditions that are expected to cause significant inconveniences and may be hazardous, these situations are normally not life threatening if caution is exercised.
13) WIND ADVISORY
This is issued for average wind speeds between 31 and 39 miles an hour, or for frequent wind gusts between 46 and 57 miles an hour.
THERE ARE OTHER WINTER WEATHER HAZARDS UNIQUE TO SPECIFIC PORTIONS OF OUR REGION:
14) LAKE EFFECT SNOW WATCH
A Lake Effect Snow Watch is issued when there is a possibility of heavy lake effect snow (accumulating 7 inches of more within a 12 hour period). Lake effect snow usually occurs in narrow bands over limited areas. The watch is issued at least 12 hours before the snow is expected to begin, however its occurrence, location, and/or timing is still uncertain.
15) LAKE EFFECT SNOW WARNING
This is issued when heavy lake effect snow is occurring, is imminent, or has a very high probability of occurring within the next 12 hours. The snow is expected to accumulate at least 7 inches with strong winds producing much high drifts. This is similar to a Winter Storm Warning for Heavy Snow, except Great Lakes induced squalls/showers occur in narrow bands and over limited areas. Lake effect snow squalls/showers can occur quite suddenly and cause blizzard-like conditions.
16) LAKE EFFECT SNOW ADVISORY
A Lake Effect Snow Advisory is issued for Great Lakes induced snowfall in western and central New York totaling between 4 and 7 inches in a 12 hour period. Blowing and drifting snow is also common in relatively limited areas and in narrow bands.