BLOG: Ice Threat Tuesday

After another weekend snow storm, today we will be in between systems. Tuesday, another storm will rip through the East, but this one will be different. This one will bring WARMER air with it! Good news, right? Well, kinda.The bad news: the air a few thousand feet above our heads will warm at a much faster rate than the air at the ground. A setup for sleet and freezing rain.TIMING: This will NOT be a problem for the morning rush. Precipitation will push in around 10am-11am on average. The threat for wintry precipitation will past until mid afternoon, maybe 3-4pm.Here's the simulated radar at 1pm: Pretty colors, but not pretty weather.SOME METEOROLOGY: How do we know that this will be sleet and freezing rain? One of the most valuable tools in a meteorologist's toolbelt is a "Skew-T" diagram, otherwise known as a "sounding". This gives us a snapshot of the entire column of air above our heads at a certain time. In these diagrams, we live at the bottom of the graph, at the Earth's surface. The top of the diagram is essentially the level at which planes fly. The green and red lines represent the temperature and dewpoint, respectively as you go up in the atmosphere.I have highlighted the freezing line.Notice as the precipitation arrives around midday, there is a small layer of above-freezing air. It's at around 5-6,000 feet. This is a sleet sounding. A reminder of what the different types of precipitation are and how they are formed:  As the warm layer gets deeper, we should see a change to freezing rain:  By late afternoon the surface temperature will finally rise above freezing. Now the atmosphere is above freezing from the ground up to 10,000 feet so we'll just have rain.  Simulated radar at 8pm:  So will this be enough ice to cause a lot of problems? It might be. We are probably looking at around 0.10" or so of ice accumulation and that can make everything very slick.  Rain will fall for much of Tuesday night. While rain amounts will likely be under an inch....we will have to watch for street and highway flooding. Many storm drains are clogged with snow right now.Thanks for reading!Eric