Updated  900am Monday / 19 March 2012

…. Rainy and Stormy Start to the New Week …
…. Severe Thunderstorms Very Likely Later Today into Tonight ….
…. Elevated SPC “Moderate” Severe Risk Area Includes all of our Area ….
…. Heavy Rainfall Amounts Expected with Some Flooding Problems ….

On this Monday morning… a surface cold front extends southward from western Nebraska southward into western Kansas and west Texas and then extending southward into Mexico. Surface high pressure is over the southeastern USA with a resulting well pronounced moist southerly surface wind across Texas.

In the upper levels of the atmosphere, a deep counterclockwise rotating trough. or line.. of upper air low pressure is situated from Washington south southeastward into Arizona with an dynamic eastward moving closed upper air low developing by tonight over New Mexico. As a result, upper level winds are strong southwesterly across Texas.

By later today into tonight.. the cold front will move slowly eastward as a strong upper level low pressure area.. lagging back behind the front.. moves slowly eastward out of west Texas. In advance of both of these weather features, upward lift and atmospheric instability will greatly intensify allowing for widespread rain showers and thunderstorms. Given the expected atmospheric instability, atmospheric lift and the forecast atmospheric wind field, a severe thunderstorm outbreak is very likely across our area with tornadoes possible.

In addition, with the slow eastward movement of this system, the precipitation will be prolonged across the area. The strongest thunderstorms will not end until the surface cold front moves through our local area early tomorrow (Tuesday).

With the upper level low pressure disturbance lingering behind the front, it is likely that scattered rain showers and thunderstorms as well as clouds will continue in the cooler post-frontal environment tomorrow and tomorrow night and into Wednesday before skies partially clear with the passage of the upper air low pressure disturbance later on  Wednesday.

Skies will be partly cloudy with a more stable and drier air mass in place Wednesday into Thursday with return southerly wind and warmer temperatures late week through next weekend.

My forecast confidence through tomorrow is high to very high. My forecast confidence Tuesday night through the remainder of the week into the weekend is very high.

For Austin and south central Texas… tonight will see rain showers and thunderstorms with isolated severe thunderstorms and periods of heavy rain possible. Lows in the 50s to near 60. South southeasterly winds will continue. For  tomorrow, morning rain showers and thunderstorms with a cold front passing by afternoon. Highs around 70. South southwesterly surface winds will become northwesterly as the cold front passes.

Have a good Monday night and Tuesday…
Meteorologist Troy Kimmel