April 18 snow day
HARRISONBURG, Va. (WHSV) - A snow day for mid-April! Yes it may seem wild after highs were around 60° Sunday, and in the mid 70s Saturday! The setup today was a feature specific to the Appalachin mountains. It was a cold air damming setup, or also known as the ‘wedge.’ This happens when high pressure is to the north/northeast and low pressure is to the south.
Cold air is heavier, more dense than warm air. So the high to the north helps that cold air to sink in between the mountains (Alleghenies and Blue Ridge). As moisture rides up from the south, it can turn into the wintry weather. What happened today, was that the cold air was in place for several hours longer before ‘warmer’ air a few thousand feeta bove the ground moved in from south to north.
So a few degrees, turned the sleet into snow and that lasted into the afternoon. Finally temperatures about 5,000′ above the ground warmed up enough into a thick enough layer to melt the snow to rain. If you noticed really big, fat snowflakes this afternoon- that was the warm air trying to work in.
This time of the year with a higher sun angle it’s very difficult to get accumulating snow during the daytime. But, with temperatures barely above freezing and heavier precipitation rates, it can happen.
So is this a record? Is this the latest measurable snowfall date? Nope, not at all. Here are the latest measurable snowfall dates across the area. For the Valley it’s typically at the end of April. For West Virginia it can be at the end of May.
In fact during the month of April there’s a 62% chance of at least a trace of snow. If we look at just the second half of April, from the 15th-30th those odds drop dramatically down to about 15%.
Here’s a look at snowfall across the area today: All reports are from the National Weather Service
You have to read this caption send in with this photo from a viewer:
So while it seems wild, to have a 30 degree temperate drop in 12 hours, well it happens. Either with a cold front or a cold air damming setup. It can go from 75 to 30 in a day. But the good news is usually this time of the year, the cold doesn’t last long. We’ll be in the 80s by the weekend. Here are some other snow photos from around the area.
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