Updated 800am CT – Monday / 15 September 2014
…. Clouds Continue with an Unsettled Weather Pattern ….
…. Passing Upper Air Low Pressure Disturbances with Better Rain Chances Tomorrow ….
On this Monday morning…. a weakening stationary front extends west southwestward from southern Alabama and coastal Mississippi across southeastern Louisiana into the northwest Gulf of Mexico off the Texas coast. As a result of this surface weather pattern, our local surface winds are east northeasterly.
In the upper levels of the atmosphere… a broad trough.. or line.. of upper level low pressure is moving eastward from the northern US plains and the western part of the northeastern US seaboard. Another strong trough of low pressure is situated off the western coast from northern and central California northward. Upper level high pressure.. acting like a lid on the atmosphere.. is weakening a bit in response to the trough to the north and covers the southern USA from the southeastern USA westward into south Texas and northern Mexico and the southwestern USA. As a result of this pattern, the upper level winds over south central Texas and the Austin metro area, about 18,000 feet above the ground, are southwesterly less than 20 mph.
With the upper level trough to our north and northeast, the upper level high pressure area (think “the lid on the atmosphere”) has continued to weaken a little and shrinking in size as upper level winds increase a bit from the west southwest.
As the weakening front over the northwest Gulf of Mexico drifts back northward, more clouds and abundant low level moisture hold in over the area today and tonight through the middle part of the week. At the same time, upper air disturbances and upper level moisture.. from the west.. traverse the area and result in the return to rain and thunderstorm chances over the next 24 hours. Afternoon high temperatures are expected to warm a bit over the coming days but still remaining at or slightly below seasonal averages.
By Thursday and Friday into the weekend, the upper level high pressure ridge (The “lid” on the atmosphere) will strengthen a bit with rain chances dropping from the forecast and clouds thinning out a bit.
Regarding my forecast, my local forecast confidence: My forecast confidence over the next two to three days is high (still concerned with exact rain timing and amounts). My confidence is high to very high Thursday and Friday through the upcoming weekend.
Have a good Monday….
Meteorologist Troy Kimmel
Contact me:
tkimmel@austin.utexas.edu
http://www.facebook.com/troykimmel