Behind all the rain we saw last week, high pressure now dominates the forecast across Texas. For us that means clear skies and comfortable fall conditions.
So just why this high pressure system is bringing us such wonderful weather? Most of us know that when high pressure is in the forecast, we can expect good weather. The high pressure system has several things working for it to bring this pattern.
First, winds are generally very light near the center of a high pressure system. The gentle breezes associated with these highs are pleasant and enjoyable on a warm afternoon, but winds also have an effect on our temperatures. It is important to note that winds do not just blow from side to side, but up and down as well. This up and down movement is very important because it mixes the air near the ground. Stronger winds work to moderate our temperatures throughout the day, meaning that overnight things will not cool down as much and during the day it will not heat up as much. Clouds have the same effect. They act like a blanket over the Earth. On cloudy nights things will be warmer than if things were clear and during the day it remains cooler.
Next, high pressure acts like a weight on the atmosphere. For clouds (and of course rain) to form, we need air to rise, but in the case of high pressure, the air sinks. The lack of clouds around a high means that we will likely see greater fluctuations in the temperatures than we would if things were cloudy and windy.
Finally, the position of the high is important. Winds move clockwise around the center of a high pressure system, so the type of air they bring into an area depends greatly on where this high is centered. In the above picture, the high is located to our Northeast. Since air moves clockwise around the high, our winds are coming from the Northeast. Imagine though that same high located to our east in the Gulf of Mexico. With the same clockwise motion, our winds would come from the South, bringing warm and moist air into the Brazos Valley from the Gulf.
This high is forecast to move to the Northeast, bringing a more easterly component to our winds. Not until next weekend are winds forecast to shift around from the South, so enjoy the cool, dry week ahead!