Kevin Myatt is The Roanoke Times' weather columnist.

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@roanoke.com
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Weather with Kevin Myatt

Recent columns

• We got graupel, but not on official record
• Moisture could get caught up in cold blast
• Forecast for Weather Journal: Partly print, with frequent Internet
• Column archive

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• Sprinkles or flurries possible Tuesday, but maybe something bigger for the weekend?
• For now, it looks like a quiet, mostly mild week ahead for SW Virginia
• Coldest morning of winter so far likely across much of Southwest Virginia; Tuesday precipitation looking doubtful
• Weather Journal blog

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Reader question: Is it harder to forecast weather in the mountains than in the open plains of the central United States?

Phil Hysell, warning coordination meteorologist at the National Weather Service in Blacksburg, worked nine years in Kansas and Missouri before moving to Virginia. His answer: It depends.

"In many cases the mountains add to the complexity and challenges of forecasting, at other times they add an element of predictability (their influences are always there since they don't move); it all depends on the situation," Hysell wrote me in an e-mail answer which he said science officer Steve Keighton also contributed to.

Terrain factors can get especially complicated in winter with borderline precipitation events. Frequently, higher elevations are colder and can get several inches of snow, while lower elevations see rain. Determining the precise elevations where precipitation types change is difficult.

Sometimes, the situation flips. Strong southerly winds aloft can raise temperatures in higher elevations several degrees above freezing while leaving pockets of cold air in the valleys -- a prescription for hard-to-pinpoint, severe, localized ice.

But in the common winter situation called cold-air damming, when cold air oozes southward from New England and eastern Canada, it is easy to determine where the cold air advance will stop because the mountains do not move.

Every region has its quirks. Difficulty of forecasting depends more on the atmospheric situation than on the geographic location.