Two fronts are poised to move through our area, one today and another Friday. Either one may produce thunderstorms but the one Friday has the greater risk of severe weather. I’ll explain why in a moment. Here is the synoptic set up (in other words, the weather features on the map -- I’ve drawn an arrow to today’s front and Friday’s front up in the northwest):
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The challenge for both weather systems is to break the “cap” -- so what exactly does that mean? As the front comes through with cold air, that cold air forces our warm air up into the atmosphere. As it goes up, it cools down even more (like when you climb a mountain). So the question is whether it keeps cooling and keeps rising and keeps cooling and keeps rising, because if it does then that air can condense, form clouds, release energy and become big thunderstorms. But what if it runs into warm air and stops the cooling and the rising? That’s the cap we always talk about. Here’s an example of the warm air in place (the cap) and the cooler air trying to break through:
This begs the question, where does that layer of warm air way above Houston come from in the first place? For us, most often, West Texas -- it’s very hot there at the ground, as you know, and their ground is at a 1,000 feet above sea level. So that ‘ground level’ air moves east to us way up in the sky and caps our atmosphere with a stable, warm layer.
Will These Fronts Break the Cap?
Friday’s front has a better chance to break the cap because today’s storms will break it down a little bit. However, neither the American Model or the European model shows a lot of big storms for us with either system:
And the European rainfall amounts are very manageable:
Nonetheless, the Storm Prediction Center has a marginal (1) to slight (2) risk for severe weather for our area on Friday. Hail and damaging winds are the greatest threat.
So keep an eye to sky -- we’ve been lucky so far this spring storm season but that luck can’t hold forever.
Frank