Updated 845am CST Wednesday / 20 November 2013
…. Clouds Continues with Rain Chances Ahead of a Strong Cold Front Early Friday ….
…. Overrunning Clouds and Rain with Much Colder Temperatures by the Weekend ….
On this Wednesday morning…. a developing warm front extends westward across the western Gulf of Mexico and into south Texas near Corpus Christi and Laredo. Surface high pressure is centered over the northeastern USA. As a result of this surface weather pattern, surface winds are east southeasterly over our area.
In the upper levels of the atmosphere… the wind pattern over the USA is shifting from a more zonal (west-to-east) upper air wind to one where a deepening trough is developing over the western USA. As a result of the overall upper level wind flow, the upper level winds over south central Texas and the Austin metro area about 18,000 feet above the ground are westerly 25 to 35 mph.
As the warm front, over south Texas, lifts northward, we’re seeing our surface winds return southeasterly with clouds and even rain chances showing up in the forecast as early as tonight. With the moisture return, clouds will continue to thicken and lower across the area.
By Friday, a strong upper air disturbance will pass by to our north and reshape the upper air wind pattern to allow for a strong cold front to move rapidly southward through the area about daybreak Friday. Heavier rain showers and thunderstorms are likely as the front moves overhead of the local area with upwards of 1 to 2 inches of rain possible.
As the cold front moves offshore of the Texas coast by late Friday, another approaching upper air disturbance will keep moisture overrunning the shallow wedge of much colder surface air with rain chances and clouds persisting through the weekend and even into next week as well. Temperatures be much below average levels by late Friday and through next weekend and into next week. The forecast pattern needs to be monitored closely since guidance is suggesting that we could see wintry precipitation develop over the northern and western parts of the area by Saturday night into Sunday.
Latest guidance suggests that another upper air low pressure disturbance will move through the area next Tuesday and this will cause surface development of a low pressure off the Texas coast. As these systems move eastward, clouds will decrease and rain chances will drop from the forecast.
Regarding my forecast, my local forecast confidence: High to very high forecast confidence through tomorrow.. then a high confidence forecast for tomorrow night into Friday. My confidence remains low to moderate for Friday through the weekend into next week (I have some questions regarding whether the air could be colder than anticipated and if winter type precipitation may come as a result of the overrunning pattern).
Have a good Wednesday…
Meteorologist Troy Kimmel
Contact me:
tkimmel@austin.utexas.edu
http://www.facebook.com/troykimmel