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WEATHER 101: Why didn't we see record warmth Sunday afternoon?

Temperatures fell way short in parts of the region Sunday

ROANOKE, Va. – Accountability is crucial, not just in this line of work, but in life as a whole. What initially was made out to be a day for shorts and t-shirts turned into something much less exciting.

Sunday, our forecast (and everyone else's) missed the mark in Roanoke, Lynchburg and Southside. No ifs, ands or buts about it.

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For this week's Weather 101, we're going to explain where our forecast went wrong.

The Wedge

If you've lived here long enough, you've heard of 'the wedge.' This occurs when northeast winds allow colder air to ooze or wedge into areas east of the Appalachian mountains. This oftentimes results in colder temperatures, fog, drizzle, mist, and rain. This is exactly what we saw Saturday. 

Fog and clouds lingered into Sunday morning for many areas along and east of the Blue Ridge Parkway, keeping the wedge in full effect for a day longer than anyone expected.

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Sun Angle

During the summer months, it's easier for the fog to break apart. Heck, even in the fall months it'll break by 10 or 11 a.m.

(There also aren't as many wedges that set up in the summer months.)

This, in some respects, is due to the angle of the sun in the sky. The higher the sun is, the more it can penetrate through the overcast and fog and get it to break apart. That's why fog dissipates fairly quickly most times in the summer and early fall. 

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However, in early December, the sun's peak angle is only 30°. It's tougher, then, for the sun to penetrate through the fog and get it to break. 

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This is part of why the wedge lasted longer, and why temperatures didn't get anywhere near our forecast for the day Sunday. 

We hold ourselves accountable for this error in the forecast, and will take it into account more when forecasting a similar pattern during this time of year.

Meteorology is an inexact science, and sometimes a piece of humble pie comes along to remind us of that.


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