Over the past 10 days we have seen the Crossroads transition from well below normal rainfall and moderate drought conditions to soaked fields, rising streams and an Invasion-of-the-Body-Snatchers outbreak of mosquitoes. What precipitated the change? The bottom line is a shift in the location of the Subtropical High, a massive summertime feature that normally is positioned from the mid latitudes into the sub tropics. When this feature is over South Texas, we experience stifling heat and humidity, since the weight of the high presses down on the atmosphere. That compression heats us up and traps humidity. The upper high has shifted into the Central Plains over the last 10 days, allowing deep tropical moisture and tropical waves to migrate westward across the Gulf of Mexico and bring us much needed rain.
That deep tropical scenario is coming to a close soon, however. The upper ridge is expanding southward and by midweek will limit our rain chances at least through Friday.