Updated 915am CT – Thursday / 30 July 2015
.. A Dry and Stable Weather Pattern Continues ..
.. Rain and Thunderstorm Chances Continue Late Tonight Through Saturday ..
On this Thursday…. a cold front extends southwestward from middle Tennessee into northern Mississippi and southern Arkansas into a surface low pressure area over central Oklahoma. From there, the cold front extends southwestward through west Texas /near Midland/ into far west Texas /near El Paso/. Surface high pressure is over the western and central Gulf of Mexico. As a result of this surface weather pattern, our local surface winds are southerly.
In the upper levels of the atmosphere.. an upper level high pressure area.. acting like a “lid” on the atmosphere.. has shifted a little further west and is centered from west Texas westward to the four corners area. An upper level low pressure trough is deepening and extends southwestward from Hudson Bay into the Great Lakes region. As a result, our upper air winds at about 18,500 feet, are light and variable.
As we’ve seen over the last few weeks, a typical summer weather pattern continues with a moist and tropical air mass holding across the area.
The upper level high pressure area will continue to shift a little more westward as the trough from Canada to over the Great Lakes continues to deepen. We’ll likely see afternoon high temperatures near 100 degrees along the IH35 corridor today.
However, by later tonight and through tomorrow and into the upcoming weekend, the upper level high pressure.. and the “lid” effect it has on the atmosphere.. will continue its retreat westward more over the southwestern USA and the four corners region. As this occurs and we find ourselves east of the high pressure area, we’ll see a more pronounced northerly wind aloft along with a slightly more unstable atmosphere. A weakening cold front.. supported by this more northerly wind aloft.. will move southeastward into northern Texas before pulling up stationary just to the north and northeast of the Austin area. Given the forecast instability as well as increased low level moisture, I will call for widely scattered rain showers and thunderstorms for the period late tonight into tomorrow and into the weekend time period. With the increased cloud cover, daytime high temperatures will be down a few degrees as well.
Beyond the weekend into early next week, upper level high pressure appears to rebuild with a vengeance over the area with rain chances dropping from the forecast and afternoon high temperatures climbing back to or above the century mark.
Have a good Thursday….
Meteorologist Troy Kimmel
Contact me:
tkimmel@austin.utexas.edu
http://www.facebook.com/troykimmel