Updated 800am CT – Tuesday / 09 September 2014
…. A Stable Late Summer Weather Pattern Returns for Now….
…. Stronger Cold Front with Rain Chances Late Friday into Early Saturday ….
On this Tuesday morning…. a high pressure area is to our east of the eastern Gulf of Mexico while a trough.. or line.. of low pressure extends southward from eastern Colorado into eastern New Mexico. As a result of this surface weather pattern, our local surface winds are south southeasterly.
In the upper levels of the atmosphere… an upper air low pressure disturbance moving through the westerly wind flow over the Great Lakes states with another disturbance extends southwestward over the northwestern USA. Upper level high pressure.. acting like a lid on the atmosphere.. covers the southern USA from the southeastern USA westward across Texas and into the southwestern USA and northern Mexico. As a result of this pattern, the upper level winds over south central Texas and the Austin metro area, about 18,000 feet above the ground, are variable generally less than 15 mph.
The upper level high pressure area above us is strengthening a bit resulting in increased atmospheric stability with abundant sunshine as well as warmer afternoon high temperatures as well.
By Thursday into Friday, as an upper air low pressure disturbance moves from the Rockies into the plains and the Mississippi Valley, it sets the stage for a cold front.. the strongest so far of the laet summer/early fall season.. move south southeastward through our area and off the Texas coast into far south Texas by Friday night into early Saturday. This is slightly slower movement than I earlier predicted so we need to monitor for future changes. Scattered rain showers and thunderstorms will occur ahead of.. along and just behind the front as it moves through our area. Drier and slightly cooler high pressure.. behind the front.. will settle into Texas for Friday night and the weekend and into Monday as the front becomes stationary over the northern Gulf of Mexico and far south Texas.
Regarding my forecast, my local forecast confidence: My forecast confidence is very high through Thursday. By Thursday night and early Friday, my confidence goes back to high (concerned with exact rain chances and timing). By Friday afternoon and Friday night into early Saturday, my forecast confidence is falls to medium (due primarily to frontal timing which is a little more uncertain now). My confidence rises back to very high by later in the day Saturday through Sunday into early next week.
Have a good Tuesday….
Meteorologist Troy Kimmel