Saturday, February 11, 2006
Snow Overspreads Area: Storm Update #2
Jason Samenow @ 10:00 PM
The next full update will be around midnight. Nowcasts will be provided every couple hours in the interim.
Moderate snow is expected overnight. The forecast remains for total accumulations to be in the range of 6-9" by morning, but more likely towards the lower end of that range.
10:00pm: Light snow currently in NW DC, with 2.5" on the ground and a temperature of 32. Areas in the north and west suburbs have received 3-6". Over the next couple hours, steady snow will continue, with intermittent periods that are light and heavy -- with 1-2 additional inches by midnight.
Where will the heaviest snow fall? Current guidance suggests generally northeast of the District. Places like Anne Arundel County may see more snow than Loudoun and Montgomery counties -- although this difference may be negated by colder temperatures to the N and W.
What was up with the rain? Is that going to affect how much snow we get? I attribute the rain to the lack of a strong high to the north that would've helped funnel cold air southward at low levels. So even though it was sufficiently cold aloft for snow, it was too warm at the surface. This fact was overlooked by all forecasters. However, as we weren't expecting most of the accumulation until night time and the amount of rain was light, I only imagine it would eat into about 5-10% of the accumulation potential.
When will the "real" snow start? The steady snow is beginning now.
When will travel be most difficult? Travel will be hazardous tonight, particularly after around 10pm. Periods of heavy snow are possible overnight, with temperatures near 30 along with 15-25 mph winds. Unless you're an experienced driver in snow and/or have 4-wheel drive, travel will likely be discouraged by local officials late tonight.
When will conditions improve? Most snow should taper off by mid morning Sunday. However, it will remain breezy and cold and it may take until Sunday night and Monday for neighborhood roads to be plowed.
Could it fizzle out? It's not fizzling out and the radar is currently quite impressive. Accumulating snow is now guaranteed. The high end totals may now be less likely due to a more easterly track of the low.
Could it turn into a crippling blockbuster storm? This scenario is not likely, but isolated areas may see double digit snow totals, particularly if there are locally heavy bands that develop, and thundersnow. Again, this would be most likely to occur northeast of DC.
What are other forecasters saying? Most forecasters are in the same ballpark forecasting this storm, although there is range of 3-14" among all forecasts. Here is a summary:
7pm: In NW DC, I measured about 3/4" on a cartop, and untreated paved surfaces are coated. Temperature is about 32, with light to moderate snow. Most areas in the metro area have received less than an inch, but reports as high as 4-5" have been reported in the mountains. Radar shows light to moderate snow, with some heavy patches throughout the area. By 10pm, expect 1-2" of new snow and deteriorating conditions in the metro area.
4:30pm: As of 4:30pm, snow was falling across much of the area (some rain mixed in S&E of town), and beginning to stick on grassy areas in the District and points north and west. Reports of accumulating snow were confined well to the west and southwest of the area--in places like Warrenton and Leesburg. Light to moderate snow, with even some heavy bursts, will continue for the next couple hours and temperatures will gradually drop to near freezing inside the beltway. Accumulations by 7pm should range from 1-2" (more in the N &W suburbs where temperatures are colder).
Moderate snow is expected overnight. The forecast remains for total accumulations to be in the range of 6-9" by morning, but more likely towards the lower end of that range.
Nowcast
10:00pm: Light snow currently in NW DC, with 2.5" on the ground and a temperature of 32. Areas in the north and west suburbs have received 3-6". Over the next couple hours, steady snow will continue, with intermittent periods that are light and heavy -- with 1-2 additional inches by midnight.
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Frequently asked Questions (updated as of 4:30pm)
Where will the heaviest snow fall? Current guidance suggests generally northeast of the District. Places like Anne Arundel County may see more snow than Loudoun and Montgomery counties -- although this difference may be negated by colder temperatures to the N and W.
What was up with the rain? Is that going to affect how much snow we get? I attribute the rain to the lack of a strong high to the north that would've helped funnel cold air southward at low levels. So even though it was sufficiently cold aloft for snow, it was too warm at the surface. This fact was overlooked by all forecasters. However, as we weren't expecting most of the accumulation until night time and the amount of rain was light, I only imagine it would eat into about 5-10% of the accumulation potential.
When will the "real" snow start? The steady snow is beginning now.
When will travel be most difficult? Travel will be hazardous tonight, particularly after around 10pm. Periods of heavy snow are possible overnight, with temperatures near 30 along with 15-25 mph winds. Unless you're an experienced driver in snow and/or have 4-wheel drive, travel will likely be discouraged by local officials late tonight.
When will conditions improve? Most snow should taper off by mid morning Sunday. However, it will remain breezy and cold and it may take until Sunday night and Monday for neighborhood roads to be plowed.
Could it fizzle out? It's not fizzling out and the radar is currently quite impressive. Accumulating snow is now guaranteed. The high end totals may now be less likely due to a more easterly track of the low.
Could it turn into a crippling blockbuster storm? This scenario is not likely, but isolated areas may see double digit snow totals, particularly if there are locally heavy bands that develop, and thundersnow. Again, this would be most likely to occur northeast of DC.
What are other forecasters saying? Most forecasters are in the same ballpark forecasting this storm, although there is range of 3-14" among all forecasts. Here is a summary:
- The National Weather Service is forecasting 6-12" (as of this afternoon)
- Channel 4 (Bob Ryan) is calling for 3-6" in the metro area, more N & W and less S & E (evening update)
- Channel 5 is forecasting 3-5" (low end forecast, as of last night--no Saturday update)
- Channel 7 is calling for 6-10" (as of this afternoon)
- Tony Pann and Topper Shutt (Channel 9) are forecasting 5-8" (as of this evening)
- Paul Kocin, Winter Weather Expert at The Weather Channel says 6-10" for DC (as of this afternoon)
- Meteorologist Dave Tolleris of WxRisk.com is forecasting 10"+ for the DC metro area.
Media/Resources
- National Radar
- WUSA Local Radar
- Closings/cancellations from WTOP
- Map of Live Temperatures around Region
- Washington Post article: Significant Snowfall Expected by Afternoon
- Washington Post article: In the Hot Seat, Tracking Snow's Advance
- Local community perspectives: Backfence.com
Previous Nowcasts
7pm: In NW DC, I measured about 3/4" on a cartop, and untreated paved surfaces are coated. Temperature is about 32, with light to moderate snow. Most areas in the metro area have received less than an inch, but reports as high as 4-5" have been reported in the mountains. Radar shows light to moderate snow, with some heavy patches throughout the area. By 10pm, expect 1-2" of new snow and deteriorating conditions in the metro area.
4:30pm: As of 4:30pm, snow was falling across much of the area (some rain mixed in S&E of town), and beginning to stick on grassy areas in the District and points north and west. Reports of accumulating snow were confined well to the west and southwest of the area--in places like Warrenton and Leesburg. Light to moderate snow, with even some heavy bursts, will continue for the next couple hours and temperatures will gradually drop to near freezing inside the beltway. Accumulations by 7pm should range from 1-2" (more in the N &W suburbs where temperatures are colder).
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