WEST MICHIGAN (May 24, 2014) — In a post from six days ago (last Sunday), I outlined in detail the fabulous holiday forecast we were anticipating (click here to see the story). It was all thanks to a ridge of high pressure building in over the region. But what does it mean?
Whenever you want dry conditions and sunshine, high pressure is the thing to wish for. If you have a barometer at home (a device that measures air pressure), you’ll notice the arrow is climbing higher as the air sinks to the ground and sends the barometer upward. This sinking air (or subsidence as we call it) is no coincidence with great weather. When air sinks, it tends to dry the atmosphere out. Sinking air is not conducive to cloud formation or precipitation.
We should note that not all pressure systems are created equal. Some weaker highs, especially if moisture gets trapped underneath a temperature inversion in the boundary layer, are known as “dirty highs” because they cannot break up the cloud cover and clear the skies. Recall that high pressure systems are the opposite of the low system counterpart. Lows pull the air inward, and force it to rise in a counterclockwise fashion. Lows tend to produce clouds, precipitation, and mainly unsettled weather.
The surface weather map attached to this story is valid for Sunday morning. Note the “H” drifting south/east of the Great Lakes, firmly anchored over the region. As the high drifts to our southeast and the circulation around these highs are in a clockwise fashion, we’ll start tapping the return flow around the high which means temperatures will warm to 80 or better the next few days. That said, a southerly wind brings warmer, more moisture laden air here as well. While a majority of Monday (Memorial Day) looks dry, shower and thunderstorm chances increase for us Monday late afternoon/evening.
For the complete West Michigan forecast, including Memorial Day and beyond, click over to www.fox17online.com/weather.