العربية
中国
Français
Deutsch
Ελληνική
हिन्दी
Italiano
日本語
Português
Русский
EspañolSNOWSQUALL
A 'Snowsquall' is a sudden snow shower with blowing snow due to high winds. It is similar to a blizzard but is localized in time or in space.
There are two types of snowsqualls
Main articles: Lake effect snow
When arctic air moves over large expanses of warmer open waters in winter, convective clouds develop which cause heavy snow showers due to the large amount of moisture available. Whiteout conditions will affect narrow corridors from shores to inland areas aligned along the prevailing wind direction. This will be enhanced when the moving air mass is uplifted by higher elevations. The name originates from the Great Lakes area of North America, however any body of water can produce them. Regions in lee of oceans, such as the Canadian Maritimes could experience such snowsqualls.
The areas affected by lake effect snow are called snowbelts and deposition rate of many inches (centimetres) of snow per hour are common is these situations. In order for lake effect snow to form, the temperature difference between the water and 850 mbar should be at least 13 °C and surface temperature be around the freezing mark. Extremely cold air over still warm water in early winter can even produce thundersnow, snow showers accompanied by lightning and thunder.
A frontal snowsquall is an intense frontal convective line, when temperature is near freezing at the surface. The strong convection that develops has enough moisture to produce whiteout conditions at places which line passes over as the wind causes intense blowing snow. This type of snowsquall generally lasts less than 30 minutes at any point along its path but the motion of the line can cover large distances.
This is similar to a line of thunderstorms in the summer but the tops of the clouds are only 5,000 to 10,000 feet (1,500 to 3,000 m), often difficult to see on radar. Forecasting these types of events is equivalent to summer severe weather forecast for squall lines: presence of a sharp frontal trough with wind shift and low level jet of more than 30 knots (55.58 km/h). However, the cold dome behind the trough is at 850 mbar instead of a higher level and must be at least -25 °C.
Both types of snowsqualls are very dangerous for motorists. The change in conditions is very sudden, and slippery conditions and abrupt loss of visibility due to whiteouts often cause multiple-vehicle collisions. In the case of lake effect snow, heavy amounts of snow can accumulate in short periods of time, possibly causing road closures and paralyzing cities.
★ Convection
★ Shower
Warnings about lake effect snow:
United States
★ Lake Effect Snow Advisory
★ Lake Effect Snow Warning
★ Severe weather terminology (United States)
Canada:
★ Snowsquall warning
★ Severe weather terminology (Canada)
★ Lake effect forecasting
★ 'What is lake effect snow?' by NOAA
★ Glossary by Environment Canada
| Contents |
| Types |
| Lake effect snow |
| Frontal snowsquall |
| Dangers |
| See also |
| Related articles |
| External links |
Types
There are two types of snowsqualls
Lake effect snow
Lake effect snowsquall
Main articles: Lake effect snow
When arctic air moves over large expanses of warmer open waters in winter, convective clouds develop which cause heavy snow showers due to the large amount of moisture available. Whiteout conditions will affect narrow corridors from shores to inland areas aligned along the prevailing wind direction. This will be enhanced when the moving air mass is uplifted by higher elevations. The name originates from the Great Lakes area of North America, however any body of water can produce them. Regions in lee of oceans, such as the Canadian Maritimes could experience such snowsqualls.
The areas affected by lake effect snow are called snowbelts and deposition rate of many inches (centimetres) of snow per hour are common is these situations. In order for lake effect snow to form, the temperature difference between the water and 850 mbar should be at least 13 °C and surface temperature be around the freezing mark. Extremely cold air over still warm water in early winter can even produce thundersnow, snow showers accompanied by lightning and thunder.
Frontal snowsquall
Frontal snowsquall moving toward Boston, Massachusetts, USA
A frontal snowsquall is an intense frontal convective line, when temperature is near freezing at the surface. The strong convection that develops has enough moisture to produce whiteout conditions at places which line passes over as the wind causes intense blowing snow. This type of snowsquall generally lasts less than 30 minutes at any point along its path but the motion of the line can cover large distances.
This is similar to a line of thunderstorms in the summer but the tops of the clouds are only 5,000 to 10,000 feet (1,500 to 3,000 m), often difficult to see on radar. Forecasting these types of events is equivalent to summer severe weather forecast for squall lines: presence of a sharp frontal trough with wind shift and low level jet of more than 30 knots (55.58 km/h). However, the cold dome behind the trough is at 850 mbar instead of a higher level and must be at least -25 °C.
Dangers
Both types of snowsqualls are very dangerous for motorists. The change in conditions is very sudden, and slippery conditions and abrupt loss of visibility due to whiteouts often cause multiple-vehicle collisions. In the case of lake effect snow, heavy amounts of snow can accumulate in short periods of time, possibly causing road closures and paralyzing cities.
See also
Related articles
★ Convection
★ Shower
Warnings about lake effect snow:
United States
★ Lake Effect Snow Advisory
★ Lake Effect Snow Warning
★ Severe weather terminology (United States)
Canada:
★ Snowsquall warning
★ Severe weather terminology (Canada)
External links
★ Lake effect forecasting
★ 'What is lake effect snow?' by NOAA
★ Glossary by Environment Canada
This article provided by Wikipedia. To edit the contents of this article, click here for original source.
psst.. try this: add to faves
Featured Companies
| Golf Holidays International | |
| Destinations Unlimited |
