Updated  130pm Thursday / 9 February 2012

…. Clouds Thicken as Another Upper Level Low to the West Causes Overrunning ….
…. Rain Chances Increase Through Late Week as Disturbances Move Overhead ….
…. Cooler Than Average Temps Now; Warmer by Late Weekend/Next Week ….

On this Thursday… surface high pressure is located to our east northeast over the middle Mississippi Valley region. A surface low pressure area with an associated north/south trough (or line) of low pressure over west Texas and eastern New Mexico.
As a result of this surface pressure pattern, a southeasterly surface wind is returning to the area.

In the upper levels of the atmosphere… a upper level low pressure area is located over the southern part of the Baja Peninsula. As a result of this pressure pattern, the upper air winds over our area of Texas are moderate southwesterly.

As the surface high pressure.. to our east northeast..  continues to move east of the area, a southeasterly surface wind is becoming reestablished over our area. Clouds, which have been slower to return to the area than I thought over the last couple of days, are finally thickening as the upper level low pressure area, over the southern part of the Baja, has already reestablished over southwesterly wind aloft with Pacific moisture moving northeastward out of Mexico contributing to an overrunning pattern.

The overrunning pattern is expected to last through late week into the weekend with upper air low pressure disturbances moving northeastward over the area and helping to create atmospheric lift and instability tonight into tomorrow. Rain chances are greatest tonight with rain probabilities decreasing by tomorrow afternoon. Rainfall amounts of 1/2 to 3/4 inch are possible. Under the clouds and with the chance of precipitation, expect temperatures to be below seasonal averages through tomorrow.

A reinforcing cold front will move into Texas by later tomorrow into early Saturday. The front will only act to reinforce the air mass in place across our area. However, clouds are expected to persist following the frontal passage with some breaks in the overcast Saturday.

By late in the weekend, we’ll see a warm up as a southerly surface wind becomes reestablished. Clouds will continue to be a factor with a renewed rain chance as the air mass becomes more unstable.

As another surface low pressure area and cold front approach us for the middle part of next week, we’ll see a better chance of rain showers and thunderstorms.

My forecast confidence through the remainder of this week is very high. My forecast confidence for the coming weekend through the middle part of next week is still medium to high (frontal timing on Wednesday and timing of precipitation being an issue).

For Austin and south central Texas… tonight will see a cloudy sky with rain.. rain showers and isolated thunderstorms. Lows in the 40s with a southeasterly wind. For tomorrow, expect a mostly cloudy sky with rain in the morning with rain chances decreasing in the afternoon. Highs around 60 with an easterly wind becoming southeasterly by afternoon.

Have a good Thursday night and Friday…
Meteorologist Troy Kimmel