Updated 845am CT – Friday / 9 May 2014
…. Another Round of Thunderstorms.. Some Possibly Severe.. Today into Tonight ….
…. Rain and Thunderstorm Chances Return Early Next Week ….
…. A Rather Strong Cold Front Moving Through Monday Night into Early Tuesday ….
On this Friday morning…. surface high pressure is to our east over the western Atlantic Ocean. A low pressure area is over central Oklahoma /1000 mb/ with a dry line.. separating continental dry air to the west from moist tropical air to the east.. extending from the low southward into southwestern Texas near Del Rio. As a result of this surface weather pattern, our local surface winds are southerly.
In the upper levels of the atmosphere… a counterclockwise rotating trough, or line, of upper air low pressure extends from southern Canada south southeastward into eastern Oklahoma and western Arkansas.. with one last disturbance embedded in the flow around this low over southwestern New Mexico and northern Mexico. The upper level winds over south central Texas and the Austin metro area about 18,000 feet above the ground, are southwesterly 30 to 40 mph.
After the bout of isolated thunderstorms last evening.. by midday today into tonight.. the last upper level low pressure disturbance out west will approach the area and create dynamic atmospheric lift. This will combine with low level moisture as well as intense daytime heating and increasing atmospheric instability to produce scattered to numerous rain showers and thunderstorms. Some of the thunderstorms, based on guidance from the NWS/Storm Prediction Center and the NWS/Austin-San Antonio, will become severe with larger hail and strong thunderstorm straight line winds and even an isolated tornado being the threat. Where precipitation occurs, rainfall amounts will average 1/2 to 1 inch with isolated higher amounts. Once the upper air low pressure disturbance moves to our northeast by late this evening, the thunderstorm and severe weather threat will end.
We’re looking at late night and early morning low clouds with an otherwise partly cloudy sky for our area Saturday through Sunday with afternoon high temperatures a bit above average.
By Monday into Monday.. in advance of a stronger cold front.. low level atmospheric moisture will combine with daytime heating.. increased atmospheric instability and atmospheric lift to produce a renewed chance of rain showers and thunderstorms. Latest indications are that heavier rain may occur with this passing system with upwards of 1 to 2 inches of rain or more possible. The cold front is currently forecast to pass the area just before daybreak Tuesday with precipitation tapering off.
Clearing.. cooler and less humid conditions will move into the area for Tuesday into Wednesday of next week.
Regarding my forecast, my local forecast confidence: My forecast confidence is medium to high for today into tonight (reference uncertainty regarding rain chances, exact rainfall timing, rainfall amounts as well as the potential for stronger, potentially severe, thunderstorms). My forecast confidence for late tonight and Saturday into Sunday is back to high to very high before falling back to medium for Monday into Monday night regarding that next cold front and the associated rain chances, timing and amounts. Forecast confidence returns to high to very high in the wake of the front for next Tuesday and Wednesday.
Have a good Friday…
Meteorologist Troy Kimmel
Contact me:
tkimmel@austin.utexas.edu
http://www.facebook.com/troykimmel