So far this season we've only had a few very minor brushes with wintry weather, with nothing more than a trace of snow and ice. That should all change on Sunday. All of the most reliable weather models are now showing a temperature and moisture scenario that should at least give us a measurable snow greater than a trace, even at the seemingly snow-resistant precip gauge at RIC. How much snow is still in question, and won't be determined with true accuracy until the system has come and gone. The model solutions are many, and the number of opinions across the blogosphere are exponentially greater.
I won't snow you, no pun intended, with confusing model lingo and acronyms, but I'll get into some specifics of what I think will occur in the Richmond area as this storm moves through. So here we go. We should begin to see rain developing during the morning hours on Sunday. A cold front will move through the metro around 6 AM on Sunday, and I expect the temperature to be around 40 degrees at sunrise. Forecast vertical temperature profiles, which we call soundings, show the precip to begin as rain. As the rain falls, we will see temperatures begin to fall as well, but only until the air becomes saturated. The point of saturation is called the wet bulb temperature, and with small differences in the temperature and low-level moisture (called dew point depression), we'll see the surface temperatures fall only into the mid 30s by noon. A northerly wind will continue to bring lower dew point air into the region during the day, so we will continue to see the temperature slowly fall to near freezing just after sunset. Although the surface temps might not reach the freezing mark until after dark, I think we will see a change from rain to snow during the afternoon hours. The snow will be heavy and wet and will only initially accumulate on grassy and elevated surfaces, but as the temps approach freezing, we should still have enough moisture around for a quick accumulation before everything comes to an end. Slick spots will be likely by Monday morning, as I expect temps to fall into the upper 20s.
This event is coming at a perfect time, with a light commute to school and work expected on Presidents Day. There will of course be some changes in the track and intensity of the storm, so I'll be back with an update and any necessary tweaking of the forecast tomorrow. Feel free to share this with friends, and you're welcome to drop by my facebook page and leave your thoughts, questions, and comments. Thanks to Claire Powell for the daffodil photo. -ZD
