Sunday, March 06, 2005
Nice day... and snow talk
Jason Samenow @ 10:00 AM
We will exceed 50 degrees today for the first time since President's Day. Seems like a pretty good day to get those errands run, take a walk, or dust off the golf clubs and head to the driving range.
Enjoy the next couple of days, because the weather will go down hill beginning Tuesday....
What makes snow stick?
There's a misconception out there, based on the last two storms, that snow that falls this time of year during the day cannot stick. It can stick, but the conditions need to be right, particularly inside the beltway where all of the buildings and concrete retain extra heat. What's necessary?
- Cold/frozen ground. A couple days of subfreezing temperatures prior to a snow event will certainly help.
- Cold air. It is hard for snow to stick with temperatures hovering right around 32. Below 30 is good, below 25 is better. But sub 25 day time temperatures this time of year are quite rare.
- Continuous moderate to heavy snow. In the last two snow events we experienced, it snowed moderately at times, but not persistently. If it snows hard for several hours on end, the snow will stick, and a frozen ground and temperatures below 30 are no longer necessary conditions.
The bottom line is that if you hear a forecast for snow the rest of the winter, pay attention to when it's going to fall, how cold it has been, how cold it's going to be and how hard it will fall. Based on those factors, you will be able to gauge how large an impact it will have.
So when will it snow next...?
Right now, there are large uncertainties in the extended forecast. Cold air will move in late Monday night (after a very mild day), but there are many waves we're trying to keep track of and it's hard to tell how strong they'll be and whether they'll "phase" (come together) and create a big storm. Right now, the snow potential isn't looking quite as good as it did a couple days ago. As always, we'll keep you informed.
How do we measure up?
There's a good a post on EasternUSWx.com's Forum about how DC's snow climatology compares to Philly, New York and Boston. We got more snow than Boston about once every 10 years, more snow than New York about twice every ten years and more snow than Philly about three times every ten years. This year, all three of those cities are way ahead of us. Compared to our 12", Philly has received nearly 30", New York 37" and Boston 78"!
Comments are closed for this archived entry | Link | 
Email this post
Email this post
