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Cut-off lows caused Sunday's surprise snow

Monday - 3/31/2014, 4:16pm  ET

WASHINGTON -- So yeeeeeeah. We got snow on Sunday.

Were you surprised? Because I certainly was.

I woke up Sunday morning in North Carolina to a Facebook newsfeed full of snow pictures and texts from friends asking, "Did you call for this?"

I laid back down, face-palmed my head and tried to think about what I forecast for Sunday. My thought process went a little something like this:

"Wait, wasn't it supposed to be sunny? Hold on, did I call for sunshine? Oh gosh, I hope I didn't call for sunshine….No, no I definitely called for rain. OK, thank goodness. ... Uh-oh, I wrote a blog on rain. Great. Maybe it is just snowing in the mountains - oh gosh, maybe I was just wish-casting when I called for just rain showers on Friday."

I sat back up and started looking at the surface observations and sure enough, it was snowing - a lot - in a lot of places.

A winter weather advisory was issued for some of the region and we were off and running. Check out how much snow we ended up with over the course of Sunday:

Snow totals from Sunday, March 30.

This was a very complex system. At 5 a.m. Sunday, the temperature measured at Ronald Reagan National Airport was around 50 degrees. By 4 p.m. it had dipped down into the mid-30s.

While low pressure was intensifying around the Delmarva Peninsula and a cut-off low was meandering around Charlottesville, cold air was being drawn down from high in the atmosphere, right down to the surface and happening relatively fast.

As the National Weather Service put it, "Cut-off lows are notorious for bringing rapidly changing weather conditions and thus forecasting for these systems is complex and this one is no exception." As the precipitation was continuing across the area, cold air was moving down to the surface rather quickly, changing the cold rain to a wet snow and/or sleet that was creating some minor accumulation.

As you may recall, I did not call for this whatsoever on Friday. While I was a little iffy about the daytime high on Friday, I never thought that we could get some snow here. Then I saw this from my colleague Brian Van de Graaff which took me from my possible wish-casting into reality:

Snow falling -- and accumulating -- in Fairfax County Sunday, March 30. (Photo courtesy of ABC7 Meteorologist Brian Van de Graaff.)

We received a lot of rain Friday through Sunday for the last little hoorah of winter in the D.C. area (at least, let's hope that is the fact).

Rainfall accumulation (the number on the left) from March 28th - March 30th (Friday - Sunday) for all three local airports. Number on the right shows surplus of rain (from average rainfall) for the month of March.

This week looks much better and more seasonable than this past weekend.

Our normal temperature for this time of year is in the low 60s, and we should have no problem making it there through at least Thursday (Friday may end up in the 50s). Don't get used to the sunshine that we are seeing today - more clouds will move into the region this week.

Temperatures will gradually go up into the mid 60s on Tuesday and near 70 on Wednesday. However, Wednesday we could see a few sprinkles in the evening hours with a better chance of rain on Thursday and Friday as a series of low pressure waves move through the area. Right now for the home opener Friday at Nats Park, it looks like rain. Pack up that Nationals rain gear — you may need it!

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