Category Archives: Weather

Snow Rollers in Idaho | The Blog of Record

Source: Snow Rollers in Idaho – The Blog of Record.

Snow Rollers

Snow Rollers

Snow Forecasting in McDowell County, NC, USA

My father, Don Smith, was a weather forecaster in the Air Force. As part of a project during this time he researched snowfall inMcDowell County, where he was from. With only two exceptions over the entire period that records had been kept, he discovered that McDowell County gets significant snow accumulation only under a very specific set of circumstances.

  • The Jet Stream must track down into the Gulf of Mexico and then angle up between Asheville and Charlotte. (The closer it passes to Asheville the more we get. Any further west and the mountains block most of the snow. The further east it passes the less we get. Due to the angle, the storm clips the southern Appalachian Mountains and snowfall for McDowell County tapers off to nothing by about Charlotte.)
  • There must be a low pressure area (clouds with precipitation) that forms or strengthens in the gulf and then rides the jet stream to our location.
  • As the low pressure system passes over us the air temperature must be at or below freezing at ground level and all the way up to the cloud layer. (If it’s freezing above but warm at the surface we get rain. If it’s warm at the surface but the ground is frozen we get freezing rain. If it’s warm above but freezing at the surface we get hail as the precipitation starts out as snow, melts to rain, and then refreezes.)

As noted above there were only two exceptions to the above pattern when my father looked at the records. One of those exceptions was a massive storm that came west over the mountains from Tennessee. The storm was so massive and moved so fast that it didn’t expend all its precipitation climbing over the Applachian Mountains so McDowell County got snow. The other exception was a Nor’Easter that came from the east. If my memory is correct the Blizzard of ’93 was also a Nor’Easter and counts as a third exception.