Wednesday, December 05, 2007
Clipper to Bring Season's First Light Snow
Best bet is a general 1" accumulation
Team Forecast @ 11:45 AM
*Snow Advisory in effect until 8pm tonight*
A Clipper System will bring the metro area its first chance of accumulating snow this season today. The most likely amount of snow accumulation is around an inch, although a little more (especially north and west of town) or less (especially downtown, south and east) is possible.
11:45am update: Clipper is pretty much behaving as expected. Tweaked snowfall total map a bit to up totals a bit to the northwest.
(*For SchoolCast -- early dismissal may be more likely than delayed opening)
When/where will the heaviest frozen precipitation fall? The snowfall will generally be light, but a few bands of moderate snow are possible -- particularly north and west of DC during the late morning and afternoon.
Will the snow stick? Not a lot in the city on paved surfaces but more in the suburbs and in grassy areas. The onset time of the snow will play an important role in how much it sticks. Any snow that falls prior to sunrise has a good chance of sticking on most surfaces, including roads. But most of the snow will fall during the day when sticking on the roads will be more difficult (except when snow is moderate-heavy). If snow showers persist into the late afternoon and evening hours, a bit more sticking on the roads could occur area-wide.
Where is the snow now? Click here for a local look and here for a regional look (at radar).
When will travel be most difficult? Visibilities could be reduced with slick spots possible between 8am and 6pm today. Be particularly careful during two periods. The first between about 8am and noon when the snow starts -- particularly north and west of DC during the morning rush hour. A second period of slick travel could occur around the evening rush (4-6pm) if snow showers linger.
What about precipitation type? This should be an all-snow event except well southeast of DC.
When will conditions improve? During the overnight hours Wednesday, as any lingering light snow tapers to flurries.
Could it fizzle out? Yes -- because the clipper will be losing moisture as it moves through the region, snowfall amounts could underperform -- especially in the city and points south and east. These same areas also stand the best chance of having temperatures rise above freezing -- which would also limit accumulation.
We believe there's a 1/4 chance there's little or no accumulation for many folks.
Could the storm bring more snow expected? Yes. If the storm is a bit moister than portrayed by the models and some bands of moderate snow develop, accumulations of several inches could occur -- especially north and west of town. Also, the heavier the precipitation, the colder it is during the daytime hours and the more the snow sticks. Finally, this is going to be a light, fluffy snow (high snow to liquid ratio) -- which will help the snow stack up if/where it sticks.
We believe there's a 1/4 chance that upwards of 2" of snow falls.
What are other forecasters saying? As of the early evening newscasts:
Will the snow stick around? What's the forecast for the next several days? The snow won't last too long (no more than 24-48 hours) thanks to a gradual warming trend that will start after this clipper departs. Thursday will be partly cloudy but quite chilly with highs near 40. Mostly cloudy on Friday with highs in the mid 40s. Saturday will be considerably warmer, with highs in the mid 50s. Downright balmy conditions are possible Sunday, with the mercury possibly topping 60!
A Clipper System will bring the metro area its first chance of accumulating snow this season today. The most likely amount of snow accumulation is around an inch, although a little more (especially north and west of town) or less (especially downtown, south and east) is possible.
11:45am update: Clipper is pretty much behaving as expected. Tweaked snowfall total map a bit to up totals a bit to the northwest.
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 Travelcast: Schoolcast*:  | |
(*For SchoolCast -- early dismissal may be more likely than delayed opening)
Frequently Asked Questions
When/where will the heaviest frozen precipitation fall? The snowfall will generally be light, but a few bands of moderate snow are possible -- particularly north and west of DC during the late morning and afternoon.
Will the snow stick? Not a lot in the city on paved surfaces but more in the suburbs and in grassy areas. The onset time of the snow will play an important role in how much it sticks. Any snow that falls prior to sunrise has a good chance of sticking on most surfaces, including roads. But most of the snow will fall during the day when sticking on the roads will be more difficult (except when snow is moderate-heavy). If snow showers persist into the late afternoon and evening hours, a bit more sticking on the roads could occur area-wide.
Where is the snow now? Click here for a local look and here for a regional look (at radar).
When will travel be most difficult? Visibilities could be reduced with slick spots possible between 8am and 6pm today. Be particularly careful during two periods. The first between about 8am and noon when the snow starts -- particularly north and west of DC during the morning rush hour. A second period of slick travel could occur around the evening rush (4-6pm) if snow showers linger.
What about precipitation type? This should be an all-snow event except well southeast of DC.
When will conditions improve? During the overnight hours Wednesday, as any lingering light snow tapers to flurries.
Could it fizzle out? Yes -- because the clipper will be losing moisture as it moves through the region, snowfall amounts could underperform -- especially in the city and points south and east. These same areas also stand the best chance of having temperatures rise above freezing -- which would also limit accumulation.
We believe there's a 1/4 chance there's little or no accumulation for many folks.
Could the storm bring more snow expected? Yes. If the storm is a bit moister than portrayed by the models and some bands of moderate snow develop, accumulations of several inches could occur -- especially north and west of town. Also, the heavier the precipitation, the colder it is during the daytime hours and the more the snow sticks. Finally, this is going to be a light, fluffy snow (high snow to liquid ratio) -- which will help the snow stack up if/where it sticks.
We believe there's a 1/4 chance that upwards of 2" of snow falls.
What are other forecasters saying? As of the early evening newscasts:
- Bob Ryan (Channel 4): Dusting to 1" in town, 1-2" western suburbs
- Sue Palka/Gary McGrady (Channel 5): Coating to an inch
- Doug Hill (Channel 7): Trace to 2"
- Topper Shutt (Channel 9): General 1"
- National Weather Service: 1-2"
Will the snow stick around? What's the forecast for the next several days? The snow won't last too long (no more than 24-48 hours) thanks to a gradual warming trend that will start after this clipper departs. Thursday will be partly cloudy but quite chilly with highs near 40. Mostly cloudy on Friday with highs in the mid 40s. Saturday will be considerably warmer, with highs in the mid 50s. Downright balmy conditions are possible Sunday, with the mercury possibly topping 60!
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