Updated 130pm CDT Wednesday / 9 May 2012

…. A Break in the Weather Gives Way to Clouds and Rain Chances Late Week ….
…. Low Pressure Disturbance to Pass Overhead Tomorrow into Early Saturday ….
…. Additional Beneficial Rainfall Upwards of 1 1/2 to 2 1/2 Inches ….

On this Wednesday… a weakening cold front extends from southeast of the mouth of the Mississippi River across the northwestern Gulf of Mexico to south of Brownsville and into Mexico then northwestward to southwest of the Texas Big Bend. A surface high pressure area.. centered over the Texas panhandle.. is building in behind the front.  As a result, a north northeasterly surface wind is blowing across our area.

In the upper levels of the atmosphere, an upper level trough is located over the southwestern USA with an upper level low pressure area.. embedded within the trough.. over northwestern Mexico. As a result of the upper air wind flow, the upper level winds are moderate west southwesterly over Texas.

With the shallow wedge of cooler air in place across the area, we’ve seen a break in the weather pattern today with some sunshine across the area.

By later tonight and tomorrow and then into late Friday and early Saturday, the strong upper air low pressure disturbance over northwestern Mexico will move slowly east northeastward from northern Mexico and across Texas. With its slow movement, several waves of rain showers and thunderstorms are likely with precipitation tapering off by Saturday morning. Brief heavy rain is possible.. upwards to 1 1/2 to 2 1/2 inches.. as the upper air disturbance weakens and moves east northeast of our area. I don’t believe that we’ll see anything other than some localized flooding (urban, small creek and stream as well as low water crossings) with this event. Our soils are more than able to handle this amount of beneficial rainfall. Although I’ll need to continue to monitor this, the current NWS/Storm Prediction Center outlooks suggests that any severe  weather threat with this system is expected to remain well south of our area.

After this upper air system weakens and departs to the northeast of the area.. upper level winds are forecast to shift more northwesterly which will support a cold front passing southeastward through the area by early and mid morning Sunday. A dry and more stable weather pattern will prevail for late in the weekend into early next week with daytime temperatures warming back to slightly below to near seasonal levels.

My forecast confidence is medium to high this week (timing of precipitation is always an issue along with exact rainfall amounts) and then high to very high confidence once the system passes on Saturday and continuing through early next week.

For Austin and south central Texas… tonight will see a mostly cloudy sky with isolated rain showers and thunderstorms after midnight. Lows in the 60s. Northeasterly wind. For tomorrow, becoming mostly cloudy with a rain showers and thunderstorm chances increasing by afternoon. Highs in the 70s to around 80 with an easterly wind.

Have a good Wednesday night and Thursday…
Meteorologist Troy Kimmel