Updated 845am CDT Tuesday / 14 May 2013
A Passing Disturbance Raises Rain Chances Locally ….
No Frontal Passages/Air Mass Changes over the Next Seven Days ….
On this Tuesday morning…. surface high pressure is over the lower Mississippi valley with low pressure over west Texas and west Oklahoma. Given this surface pressure pattern, surface winds are southerly across our area of the state.
In the upper levels of the atmosphere… a deep upper air trough.. or north/south line of low pressure.. is over the east coast while another trough is off the west coast of the USA. An upper level low is over northern Mexico. Given this upper air pattern, winds over south central Texas and the Austin metro area about 18,000 feet above the ground are westerly 8 to 18 mph.
As the southerly surface winds continue.. additional low level moisture is being brought northward into the area.
By later this afternoon into tonight and early Wednesday.. a upper air low pressure storm system will pass slowly west-to-east to the north of the local area. As this system passes and creates lift in the atmosphere, enough low level moisture and atmospheric instability will become available for scattered rain showers and thunderstorms especially by tonight into tomorrow. Latest NWS rainfall forecast guidance suggests that 1/4 to 1/2 inch of rain could fall over our area as this system passes slowly eastward overhead.
In the wake of the upper air disturbance, rain chances will diminish mid into late week with a more stable late spring weather pattern taking hold late week and through the weekend. With this pattern, you can expect late night and early morning low cloudiness, otherwise a partly cloudy sky with seasonal temperatures.
Have a good Tuesday Night and Wednesday…
Meteorologist Troy Kimmel