Updated  130pm Friday / 3 February 2012

…. Upper Air Low Pressure Storm System and Cold Front Move Through Tonight ….
…. Rain and Thunderstorm Chances Continue into Early Saturday Morning ….
…. Cooler Temperatures for the Weekend Through Much of Next Week ….

On this Friday… a deepening surface low pressure area is over western Oklahoma with a warm front extending from the low southeastward into central Louisiana. A cold front extends southwestward from the Oklahoma low into far west Texas and southern New Mexico. As a result of this surface pressure pattern, a southerly surface wind is blowing across our area.

In the upper levels of the atmosphere… a rather large and deep upper air low pressure disturbance extends from the four corners region into eastern Colorado. As a result of this pressure pattern, the upper air winds over our area of Texas are moderate southwesterly.

A southerly wind has continued to bring plenty of warm and moist air into our area in the wake of the warm front that passed back northward over our area Thursday afternoon.

A strong cold front.. in combination with the strong upper air low pressure disturbance.. is due by later tonight into early tomorrow with scattered to numerous rain showers and thunderstorms. The latest guidance suggests that upwards of 1 inch of rainfall expected with isolated heavier totals in areas east and northeast of the Austin metro area. The NWS / Austin-San Antonio has issued a flash flood watch for areas along and east of the IH35 corridor, but, at this time, due to quick forward progress of the front, I do not see any major problems as a result of this system. I might point out that Travis County’s flash flood guidance, also a NWS product, says that it would take 2.10″ of rain in a 1 hour period (or 2.7 inches in 3 hours, or 3.6 inches in 6 hours) to initiate flash flooding. I just don’t see this happening in any type of widespread manner across our area.

Surface high pressure.. behind the cold front..  will move settle southward in the wake of the front with cooler temperatures area wide into the weekend into early next week with lingering clouds being the main feature of our weekend weather. Even a few sprinkles are possible back in cooler air as passing upper air low pressure disturbances make their way over the area over the weekend.

The best chance of seeing sun will be in the Monday through Tuesday time period with another increase in cloud cover due for the middle and latter part of next week.

My forecast confidence today through tomorrow is high to very high. My forecast confidence for Sunday through the early and mid part of next week is medium (due to the possibility of more cloudiness and the timing of those rain chances as suggested by some models as weak upper air disturbances move west-to-east across the area).

For Austin and south central Texas… tonight will scattered to numerous rain showers and thunderstorms. Lows in the 50s with a southerly wind shifting northerly after midnight in the wake of the cold front. For tomorrow, a mostly cloudy sky and cooler with a chance of early morning rain and then a slim chance in the afternoon. Highs in the 50s to near 60 with northerly wind.

Have a good Friday night and Saturday…
Meteorologist Troy Kimmel