Updated 800am CT – Thursday / 18 December 2014
…. Upper Level Storm System Moves Overhead Tonight into Friday ….
…. Somewhat Drier Weather for the Weekend ….
On this Thursday morning…. a low pressure area is over deep south Texas with a developing warm front extending eastward from the low to along the middle and upper Texas coast then southeastward into the central Gulf of Mexico. Another developing surface low pressure area is over far west Texas with a stationary front extending northwestward from west Texas into eastern Colorado. High pressure.. well to our northeast.. is over the Lake Superior southward into Illinois. As a result of this surface weather pattern, our local surface winds are light and variable to light northeasterly.
In the upper levels of the atmosphere.. a deepening upper level trough.. or line.. of low pressure is located over the western half of the USA with a strong disturbance within the trough over southeastern Arizona. As a result, our upper air winds at about 18,500 feet are southwesterly 40 to 50 mph.
Clouds and rain chances continue in the forecast as the upper level low pressure storm system out west approaches and then moves across the area by tonight into Friday. As it moves by, it will create abundant atmospheric lift and, as a result, we’ll see a much better chance of rain.. rain showers and thunderstorms by tonight into Friday. The latest NWS guidance suggests that we’ll be upwards of 1 to 2 inches of rain in areas east of IH35 with lesser amounts west of the corridor. As the system departs to the northeast tomorrow, a surface cold front will move through with a surface high pressure area once again building in with somewhat drier and more stable air with at least a little sunshine by the weekend.
Longer range guidance continues to be less bullish regarding the next upper air low pressure storm system for early next week. As a result, we’ll see some additional clouds Monday with skies clearing by Tuesday as another weak cold front passes. Wednesday and Thursday, Christmas Eve and Christmas Day, look good at this time with lots of sunshine and slightly warmer temperatures returning.
Long range outlook is still suggesting some potential for cloudy.. wetter and colder weather to arrive in the late week into weekend time period about 8 to 9 days out.
Regarding my forecast, my local forecast confidence: My forecast confidence is medium to high through tomorrow with rainfall timing and amounts being the question. My forecast confidence rises back to very high for Friday night through early next week.
Have a good Thursday….
Meteorologist Troy Kimmel
Contact me:
tkimmel@austin.utexas.edu
http://www.facebook.com/troykimmel