Sunday, January 6, 2013

January 9 Severe Weather Event

The Storm Prediction Center is outlining a severe weather threat for January 9, 2013 in southeast Texas. This includes the cities of Houston and Corpus Christi. Let's see what will be causing this severe weather situation.

A storm system is currently digging into the Southwest as a positively-tilted system, meaning the highest vorticity values are tilted towards the southwest. As the storm moves along the US/Mexico border, it will turn from a positive tilt to a neutral tilt, and eventually a negative tilt as seen above. When you get that negative tilt, colder air flows in the upper levels of the atmosphere, leading to increased instability over the region within the warm sector.

The models are still uneasy on this system, but what is agreed on is the presence of either a negatively-tilted storm or a closed low. Either one can create significant precipitation and a severe weather situation. The ECMWF model is showing a closed low, whereas the GFS model above has the negative tilt within the system. This slight difference could be a huge game-changer for this severe weather set-up, whether it's a bust or an outbreak.

At the moment, I think this event will have a fair severe weather potential, but the lack of strong upper level winds and only moderate lower level winds, I expect this to be a more low-end severe weather event, not as big as it may seem. Model uncertainty only adds to my lack of confidence.

My forecast:
Red: Likely Severe Weather
Yellow: Possible Severe Weather


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