Post by Jeb on Dec 18, 2013 8:13:31 GMT
December 17-18, 2013 surprise snow band
Tonight all that was forecast was a 40 percent chance of snow showers with no accumulation. The disturbance ended up south of the expected track and a brief band set up over northern Virginia just southeast of DCA. I had moderate rainfall which began to mix with some wet snow around 1150pm. As the band moved overhead, the precipitation changed to all wet snow and became heavy, with big heavy wet snowflakes over an inch in diameter. These were outright heavy snow rates, rates so sick that the roads became covered with snow and half of an inch of heavy wet snow piled up on all surfaces: housetops, the roadways, driveways, the lawn, particularly the north side which I mowed very low in order to be able to measure snow more accurately, fence tops, the trees, the bushes and the car tops. I measured the heavy wet snow in at least seventeen different places. It averaged out to half an inch.
During the moderate rainfall the temperature fell from 35 degrees to 33 degrees, then the snow band mixed out to all wet snow and the temperature fell to 31 degrees. The big heavy wet flakes looked great in the streetlights. Too bad we didn't have a north wind to blow em past the streetlights. I made the mistake of looking straight up and got temporarily blinded by huge heavy wet snowflakes from this sick, sick superband. I estimate that this absolutely sick band lasted for about 40 minutes. I wasn't timing it - I was just mesmerized by these HUGE wet snowflakes that swirled around and covered every surface.
It was interesting how these sick snow rates over came the relatively mild road surfaces. The road was wet during the rain. Then the rain changed to snow which became heavy. At first the road stayed wet, with the typical high reflectivity of streetlights off of a wet road. Then, as the sick rates overcame the relatively mild road temps, the reflectivity changed. It got slushy as the torrent of heavy wet snowflakes set up a state of preconsolidation. Then, the roads turned white as the torrent of heavy snow continued to pile up heavy wet dendrites.
If we had gotten the moisture that Richmond had gotten and it had been about ten degrees colder, DCA and most of northern Virginia would have gotten shellacked by at least eight inches of snow tonight.
The best snow events are the ones that are not predicted or expected. I really did not expect to see any snow tonight - I thought flurries were a major stretch. But I NEVER EVER expected this sick superband straight out of an SNE coastal blizzard! It was sicker than the bubonic plague in 1348! The moderate rain changed to all wet snow and then the heavy wet flakes poured down, at least an inch in diameter and for 40 minutes, all was right in the world.
Because it was totally unexpected, I enjoyed this half inch far more than the inch and a half a week ago. Surprise overperformers are by far the best!
I've added this new half inch to my seasonal totals and may extend the snow cover days tally by one more day, to 10 days.
(This event is referred to as the Dec 17-18 event because it began before midnight on Dec 17 then extended for about 30-40 minutes into Dec 18).
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Tonight all that was forecast was a 40 percent chance of snow showers with no accumulation. The disturbance ended up south of the expected track and a brief band set up over northern Virginia just southeast of DCA. I had moderate rainfall which began to mix with some wet snow around 1150pm. As the band moved overhead, the precipitation changed to all wet snow and became heavy, with big heavy wet snowflakes over an inch in diameter. These were outright heavy snow rates, rates so sick that the roads became covered with snow and half of an inch of heavy wet snow piled up on all surfaces: housetops, the roadways, driveways, the lawn, particularly the north side which I mowed very low in order to be able to measure snow more accurately, fence tops, the trees, the bushes and the car tops. I measured the heavy wet snow in at least seventeen different places. It averaged out to half an inch.
During the moderate rainfall the temperature fell from 35 degrees to 33 degrees, then the snow band mixed out to all wet snow and the temperature fell to 31 degrees. The big heavy wet flakes looked great in the streetlights. Too bad we didn't have a north wind to blow em past the streetlights. I made the mistake of looking straight up and got temporarily blinded by huge heavy wet snowflakes from this sick, sick superband. I estimate that this absolutely sick band lasted for about 40 minutes. I wasn't timing it - I was just mesmerized by these HUGE wet snowflakes that swirled around and covered every surface.
It was interesting how these sick snow rates over came the relatively mild road surfaces. The road was wet during the rain. Then the rain changed to snow which became heavy. At first the road stayed wet, with the typical high reflectivity of streetlights off of a wet road. Then, as the sick rates overcame the relatively mild road temps, the reflectivity changed. It got slushy as the torrent of heavy wet snowflakes set up a state of preconsolidation. Then, the roads turned white as the torrent of heavy snow continued to pile up heavy wet dendrites.
If we had gotten the moisture that Richmond had gotten and it had been about ten degrees colder, DCA and most of northern Virginia would have gotten shellacked by at least eight inches of snow tonight.
The best snow events are the ones that are not predicted or expected. I really did not expect to see any snow tonight - I thought flurries were a major stretch. But I NEVER EVER expected this sick superband straight out of an SNE coastal blizzard! It was sicker than the bubonic plague in 1348! The moderate rain changed to all wet snow and then the heavy wet flakes poured down, at least an inch in diameter and for 40 minutes, all was right in the world.
Because it was totally unexpected, I enjoyed this half inch far more than the inch and a half a week ago. Surprise overperformers are by far the best!
I've added this new half inch to my seasonal totals and may extend the snow cover days tally by one more day, to 10 days.
(This event is referred to as the Dec 17-18 event because it began before midnight on Dec 17 then extended for about 30-40 minutes into Dec 18).
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