Sunday’s challenging ice forecastJanuary 26th, 2013 at 12:38 pm by Nicholas Ferreri under Weather
The potential for a wintry mix of precipitation that includes some ice accumulation remains for Sunday afternoon and night. The overall set up of this system and the forecasted ice accumulation amounts remain the same since Jonathan blogged last night, likely 0.1″-0.3″ across the region.
Another aspect that remains the same is the complexity of this forecast. As Jonathan mentioned, a degree or two difference in temperature will make all the difference, especially here at ground level where it will be the determining factor in freezing rain vs. rain.
The computer models agree the system is coming, but disagree as to timing and precipitation amounts. I’ve posted snapshots of both the GFS and NAM forecast model data through Bufkit (a forecast tool we use in the weather center – click on the images to see all the data enlarged and full screen). When you look at these images, note that the timestamp on the bottom runs from right to left and that the blue bars represent snow, the red bars represent freezing rain or sleet and the green bars represent rain.
If the precipitation starts earlier in the day, as the GFS model suggests, we’d have a brief period of snow before it changes over to sleet and freezing rain (and, eventually, rain). With conditions in the atmosphere warming through the day, if the precipitation holds off until later, there won’t be any snow…just sleet, freezing rain and rain.
So, timing and atmospheric temperatures will hold the key to what actually pans out tomorrow. Future runs of the computer models, which will come in now through tomorrow afternoon, will give us an increasingly better view of how the day will pan out. We’ll keep you posted with the latest video forecasts here and over on our NewsChannel 15 newscasts.