Updated 130pm CDT Thursday / 19 April 2012

…. Humidity on the Increase as Low Pressure Develops to our Northwest ….
…. A Cold Front with Relatively Slim Chance of Rain Due Tomorrow ….
…. Sunny Skies with Cooler Temperatures For the Weekend into the New Week ….

On this Thursday… surface high pressure is situated from the northeastern USA southwestward into the lower Mississippi Valley. A southeastward moving cold front extends from Missouri into Kansas and into northwest Oklahoma and northwest Texas and northern New Mexico. As a result, a southerly surface wind has returned to our area.

In the upper levels of the atmosphere, an upper level trough of low pressure is deepening over the southwestern USA and northwestern Mexico. As a result of the upper air wind flow, the upper level winds are moderate westerly over our area of Texas.

The surface high pressure has now shifted well east of the area with a return of low level moisture underway from the Gulf of Mexico.

I’m still watch the approaching cold front to our northwest.. which I still expect will move through the area by Friday mid afternoon. With low level moisture now on the increase, I’m still watching to see whether the quantity of enough low level moisture will be great enough to allow for rain showers and thunderstorms tomorrow. It now looks like that the moisture will be great enough but the atmospheric wind field and atmospheric instability will be the limiting factors. The NWS/Storm Prediction Center has placed most of south Texas.. mainly south and southeast of our area.. in a “slight” risk area for severe thunderstorms tomorrow as the front passes. I still think the best rain chances will be greatest along and east of the IH35 corridor with severe chances greatest to our south and east. I will increase rainfall probabilities slightly for the IH35 corridor and will specifically mention higher rain chances in our southeastern most counties. NWS rainfall guidance still suggests rainfall will be limited due to the fast forward movement of the front; rainfall of 1/4″ or less in most areas with a little more in our easternmost counties.

High pressure, characterized by cooler and drier air, will build into the area with the passage of the front with a typical spring outdoor weekend in store Saturday.. Sunday and into the new week.

High pressure will move east of the area by late Monday into Tuesday along with the development of a trough of low pressure to our west; as a result, a south southeasterly surface winds will return with a return of low level moisture.

My forecast confidence continues high to very high through the seven day forecast period.

For Austin and south central Texas… tonight will see a partly cloudy sky early.. low clouds late. Lows in the 60s. South southeasterly wind. For tomorrow, it’ll be partly cloudy with widely scattered to scattered rain showers and thunderstorms with an afternoon cold front. Highs around 80 with a southerly wind becoming northerly.

Have a good Thursday night and Friday…
Meteorologist Troy Kimmel