Updated 915am CT – Wednesday / 22 April 2015
.. A More Unstable Air Mass ..
.. Rain and Thunderstorm Chances Through Late Week ..
On this Wednesday…. a southward moving cold front extends from the Missouri bootheel into northern Arkansas and Oklahoma and northwestward into Colorado. A weak low pressure are is over west Texas and eastern New Mexico west southwest of Amarillo with a trough.. or line.. of low pressure from the low southward into far southwest Texas. As a result of this surface weather pattern, our local surface winds are southeasterly.
In the upper levels of the atmosphere.. an strong counterclockwise rotating upper air low pressure area is located just northeast of Lake Superior. Another strong upper level low pressure disturbance is over southern California. As a result, our upper air winds at about 18,500 feet are westerly at 50 to 60 mph.
With our return south southeasterly surface wind, we’re seeing low level moisture continuing to increase across the area. We’re also seeing a moderate westerly upper level winds are bringing some mid and high level Pacific moisture.. in the form of mid and high clouds.. to our local area.
A series of weak cold fronts will approach the area from the north by tomorrow through the latter part of the week. Even though I don’t see the fronts making their way this far south through the end of the week, beginning today, we’ll be seeing the influence of passing upper air disturbances from the counter clockwise rotating system over southern California. This resultant increased upward motion in the atmosphere along with a more moist and unstable air mass will bring us increased clouds as well as rain and thunderstorms chances beginning today and continuing through the remainder of the week.
The latest NWS/Storm Prediction Center guidance suggests the possibility of stronger.. potentially severe.. thunderstorms for parts of Texas (including parts of our local area) for today through Thursday and Friday. In addition, the latest NWS rainfall forecast guidance now shows the potential of 3/4 to 1 1/2 inch of rain between now and Saturday.
A drier and more stable air mass return Saturday into Sunday with more sunshine expected. Another approaching front along with a passing upper air low pressure disturbance will result in the return of rain and thunderstorm chances to the forecast by Sunday night into Monday.
Have a good Wednesday….
Meteorologist Troy Kimmel
Contact me:
tkimmel@austin.utexas.edu
http://www.facebook.com/troykimmel