If you watched me on the air last weekend, I spoke about temperatures for this weekend fondly. I said something along the lines of “we’re not expecting dry weather for Saturday and if that stays and we get some sunshine, our temps will soar into the 60s.”
Okay so in the end, I was wrong. Highs yesterday were in the 40s for most of the state away from the shoreline, we did get into the mid 50s in spots but the clouds won out hugely throughout the day. So why would I say “if we get sun, bla bla bla”. Well that’s because as a forecaster, it’s my job (and responsibility) to go much deeper than look at predicted temperatures to give you an accurate temperature forecast. This time of the year, as the weather heats up slowly but surely, it especially makes all the difference when the sun is out and shining. In the case of this weekend, that clearly did not happen. So what made me say that it would be so much warmer than the forecasted temps if we saw sun?
In order to figure that, you simply just have to look up. Okay don’t literally look up, but look higher than the ground. Everything that we forecast is from six feet down to the ground. From rain, to icy spots, to the temperatures. We even forecast wind at just a handful of feet off the ground. The problem is, there are a TON of factors that change how the weather will be at the ground. From humidity to elevation, trees to even the color of the ground (ie grass, pavement, etc.). So a fantastic resource we have is the sky. Forecast for 5000 feet off the ground, and eliminate most of the “turbulence” from the forecast. Trees don’t get in your way, elevation doesn’t matter because you’re at a constant height!
One way we look at how things will be high up is by looking at a temperature profile over time at that 5000 feet level. This is a great indication of whether we have warm air moving in, or cold air moving in. This past weekend, we were looking at milder air high up at that level. Don’t forget this time of the year a little bit of sun goes a long way. Imagine the difference between a cloudy day and a sunny day during the middle of September, and that might make it more clear. Right now, our sun angle is as high as it is around September 16th but our temperature isn’t. That’s because the ground takes time to heat up, clouds get in the way of warming us quickly, and cold water also cools us down.
The punchline is, when the suns angle is this high in the sky and we have mild air available in the atmosphere, the difference between clouds and sun can be the difference of 20 degrees or more! At least we have some spring in the forecast!