Updated 845am CDT Monday / 13 May 2013
A Dry Start to the Week ….
A Passing Disturbance Gives Us Mid Week Rain Chances ….
No Frontal Passages/Air Mass Changes over the Next Seven Days ….
On this Monday 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.
A fairly dry and stable weather pattern continues as we start a new week across south central Texas. With surface high pressure now to our east and with low pressure deepening to our west.. a southerly surface wind flow continues across our area.
As the southerly winds continue.. additional low level moisture will be moving into the area with late night and early morning low cloudiness picking up tonight into early Tuesday.
By late tomorrow into tomorrow night and 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 tomorrow night into Wednesday and Wednesday night. 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 Thursday into Friday 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 Monday Night and Tuesday…
Meteorologist Troy Kimmel