winter weather october 17, 2007. winter weather a winter storm is a low-pressure system that covers...
TRANSCRIPT
![Page 1: Winter Weather October 17, 2007. Winter Weather A winter storm is a low-pressure system that covers a large area and contains weather fronts. In the Northern](https://reader033.vdocument.in/reader033/viewer/2022051417/56649ecb5503460f94bd9e51/html5/thumbnails/1.jpg)
Winter Weather
October 17, 2007
![Page 2: Winter Weather October 17, 2007. Winter Weather A winter storm is a low-pressure system that covers a large area and contains weather fronts. In the Northern](https://reader033.vdocument.in/reader033/viewer/2022051417/56649ecb5503460f94bd9e51/html5/thumbnails/2.jpg)
Winter Weather
• A winter storm is a low-pressure system that covers a large area and contains weather fronts.
• In the Northern Hemisphere, circulation is counterclockwise
• Fronts can produce rain, sleet, freezing rain, or snow
![Page 3: Winter Weather October 17, 2007. Winter Weather A winter storm is a low-pressure system that covers a large area and contains weather fronts. In the Northern](https://reader033.vdocument.in/reader033/viewer/2022051417/56649ecb5503460f94bd9e51/html5/thumbnails/3.jpg)
Winter Cyclones• Winter cyclones are produced by (or spin
off of) the Aleutian and Icelandic Lows (both semi-permanent pressure cells)
• They can impact weather between September and May
• Most intense in January and February
• The severity of the storm can be determined by checking the pressure at the storm’s center – anything below 1000mb is severe
![Page 4: Winter Weather October 17, 2007. Winter Weather A winter storm is a low-pressure system that covers a large area and contains weather fronts. In the Northern](https://reader033.vdocument.in/reader033/viewer/2022051417/56649ecb5503460f94bd9e51/html5/thumbnails/4.jpg)
Winter Lows
![Page 5: Winter Weather October 17, 2007. Winter Weather A winter storm is a low-pressure system that covers a large area and contains weather fronts. In the Northern](https://reader033.vdocument.in/reader033/viewer/2022051417/56649ecb5503460f94bd9e51/html5/thumbnails/5.jpg)
• The severity of winter cyclones depends on – Latitude – Distance from the ocean
• Source region
– Continentality• Southern Italy and Nebraska are at the same
latitude
– Topography• Mountains alter wind patterns
– Altitude • Influence temperature distribution
![Page 6: Winter Weather October 17, 2007. Winter Weather A winter storm is a low-pressure system that covers a large area and contains weather fronts. In the Northern](https://reader033.vdocument.in/reader033/viewer/2022051417/56649ecb5503460f94bd9e51/html5/thumbnails/6.jpg)
Jet Stream
• Parks over the US during the winter
• Can change position and contour often, or stay in the same position for months
• Persistent winter ridges produce a warm, dry winter
• Persistent winter troughs produce a cold, wet winter and spring floods
![Page 7: Winter Weather October 17, 2007. Winter Weather A winter storm is a low-pressure system that covers a large area and contains weather fronts. In the Northern](https://reader033.vdocument.in/reader033/viewer/2022051417/56649ecb5503460f94bd9e51/html5/thumbnails/7.jpg)
Sleet and Freezing Rain
• The most dangerous winter weather because no one takes them seriously
• Ice pellets or snowflakes that melt as they fall, but refreeze before hitting the surface
• Freezing rain freezes on the first thing it hits: power lines, roads, trees, geese…
• If more than 1 in of ice forms at the surface, it is termed an ice storm
![Page 8: Winter Weather October 17, 2007. Winter Weather A winter storm is a low-pressure system that covers a large area and contains weather fronts. In the Northern](https://reader033.vdocument.in/reader033/viewer/2022051417/56649ecb5503460f94bd9e51/html5/thumbnails/8.jpg)
Freezing Rain
![Page 9: Winter Weather October 17, 2007. Winter Weather A winter storm is a low-pressure system that covers a large area and contains weather fronts. In the Northern](https://reader033.vdocument.in/reader033/viewer/2022051417/56649ecb5503460f94bd9e51/html5/thumbnails/9.jpg)
Sleet
![Page 10: Winter Weather October 17, 2007. Winter Weather A winter storm is a low-pressure system that covers a large area and contains weather fronts. In the Northern](https://reader033.vdocument.in/reader033/viewer/2022051417/56649ecb5503460f94bd9e51/html5/thumbnails/10.jpg)
Hail
• Hail consists of ice pellets formed in roughly concentric layers
• Formed when water is frozen in the atmosphere. The ice pellet falls and encounters water, which freezes to the ice pellet forming a second layer
• The size of hail is determined by the strength of the updraft
• Hail has more water volume, snowflakes have more air volume
![Page 11: Winter Weather October 17, 2007. Winter Weather A winter storm is a low-pressure system that covers a large area and contains weather fronts. In the Northern](https://reader033.vdocument.in/reader033/viewer/2022051417/56649ecb5503460f94bd9e51/html5/thumbnails/11.jpg)
Hailstones
![Page 12: Winter Weather October 17, 2007. Winter Weather A winter storm is a low-pressure system that covers a large area and contains weather fronts. In the Northern](https://reader033.vdocument.in/reader033/viewer/2022051417/56649ecb5503460f94bd9e51/html5/thumbnails/12.jpg)
Snow
• Snow is precipitation in the form of frozen water with a crystalline structure
• For powdery snow, 8-12 inches of snow will melt into 1 inch of water
• For wet snow, 4-6 inches of snow will melt into 1 inch of water
![Page 13: Winter Weather October 17, 2007. Winter Weather A winter storm is a low-pressure system that covers a large area and contains weather fronts. In the Northern](https://reader033.vdocument.in/reader033/viewer/2022051417/56649ecb5503460f94bd9e51/html5/thumbnails/13.jpg)
Winter Precipitation
![Page 14: Winter Weather October 17, 2007. Winter Weather A winter storm is a low-pressure system that covers a large area and contains weather fronts. In the Northern](https://reader033.vdocument.in/reader033/viewer/2022051417/56649ecb5503460f94bd9e51/html5/thumbnails/14.jpg)
Drifting Snow
• Drift control used to prevent roads from becoming impassible
• Temporary snow fences erected to capture snow blowing from the west and northwest
• Rows of conifers also used
![Page 15: Winter Weather October 17, 2007. Winter Weather A winter storm is a low-pressure system that covers a large area and contains weather fronts. In the Northern](https://reader033.vdocument.in/reader033/viewer/2022051417/56649ecb5503460f94bd9e51/html5/thumbnails/15.jpg)
Blizzards
• Blizzards are characterized by blowing and drifting snow, limited visibility, and cold temperatures
• Occur on the polar sides of fronts behind cold fronts
• Temperatures below 25°F and winds above 35mph
• Blizzards are strongest when reaching the farthest point south in the jet stream
![Page 16: Winter Weather October 17, 2007. Winter Weather A winter storm is a low-pressure system that covers a large area and contains weather fronts. In the Northern](https://reader033.vdocument.in/reader033/viewer/2022051417/56649ecb5503460f94bd9e51/html5/thumbnails/16.jpg)
• Rain into snow– Precipitation changes from rain into snow as a
cold front passes– Wind changes from SSW to WNW as the front
passes
• Snow into rain– When a center of low pressure passes over
an area before the warm front– Snow is melted into rain– Causes freezing rain and ice storms
![Page 17: Winter Weather October 17, 2007. Winter Weather A winter storm is a low-pressure system that covers a large area and contains weather fronts. In the Northern](https://reader033.vdocument.in/reader033/viewer/2022051417/56649ecb5503460f94bd9e51/html5/thumbnails/17.jpg)
Nor’easters
• Aka Northeasterns
• When trough sets up over Atlantic seaboard
• Atlantic Ocean feeds extreme snow storms along the coast
• Winds out of the NE
• Snow 1-4 feet deep, coastal flooding, beach erosion
![Page 18: Winter Weather October 17, 2007. Winter Weather A winter storm is a low-pressure system that covers a large area and contains weather fronts. In the Northern](https://reader033.vdocument.in/reader033/viewer/2022051417/56649ecb5503460f94bd9e51/html5/thumbnails/18.jpg)
Cold Air Damming
• When high pressure sets up over the NE US or eastern Canada, it forces cold air into the Appalachian Mountains
• The air is too dense to rise over the mountains, so it becomes trapped
• This produces extreme temperatures, ice storms, freezing rain, and/or blizzards
• Example, Blizzard of 1993
![Page 19: Winter Weather October 17, 2007. Winter Weather A winter storm is a low-pressure system that covers a large area and contains weather fronts. In the Northern](https://reader033.vdocument.in/reader033/viewer/2022051417/56649ecb5503460f94bd9e51/html5/thumbnails/19.jpg)
Cold Air Damming
![Page 20: Winter Weather October 17, 2007. Winter Weather A winter storm is a low-pressure system that covers a large area and contains weather fronts. In the Northern](https://reader033.vdocument.in/reader033/viewer/2022051417/56649ecb5503460f94bd9e51/html5/thumbnails/20.jpg)
FYI
• Alcohol increases the danger of hypothermia (which is extremely low body temperature)– It impairs judgment– It causes small blood vessels in the skin to
dilate, increasing the rate of heat loss from the body
![Page 21: Winter Weather October 17, 2007. Winter Weather A winter storm is a low-pressure system that covers a large area and contains weather fronts. In the Northern](https://reader033.vdocument.in/reader033/viewer/2022051417/56649ecb5503460f94bd9e51/html5/thumbnails/21.jpg)
Folklore• The wooly boogers!
– Their coloring predicts winter weather
• Hornets– Placement of nests predicts winter weather
• Punxsutawney Phil
![Page 22: Winter Weather October 17, 2007. Winter Weather A winter storm is a low-pressure system that covers a large area and contains weather fronts. In the Northern](https://reader033.vdocument.in/reader033/viewer/2022051417/56649ecb5503460f94bd9e51/html5/thumbnails/22.jpg)
![Page 23: Winter Weather October 17, 2007. Winter Weather A winter storm is a low-pressure system that covers a large area and contains weather fronts. In the Northern](https://reader033.vdocument.in/reader033/viewer/2022051417/56649ecb5503460f94bd9e51/html5/thumbnails/23.jpg)