Tuesday, August 05, 2008

20080805 Wx Discussion I (1818Z)


Today should prove very, very interesting. We have some moisture and we have some lingering boundaries from yesterday's convection. We also have mid-level moisture ... lots of mid-level moisture ... ready to be tapped and exploited. What we don't have is instability today. The surface temperature would have to approach 90ºF to lift us today and with noon-time temperatures in the upper 70's (thank you cold front!), 90ºF is a stretch. Also working against us is a lack of reasonable shear. Head north and you'll find it, but the metro area is lacking, not to mention warm temperatures at 700mb, effectively capping the atmosphere. Winds are erratic and weak until you reach 500mb where they blow out of the west

So, what does this all mean?

Well, we'll have to look to the mountains and foothills to see decent lapse rates capable of driving convection. With the moisture in place, this shouldn't be a problem at all. Mid-level outflow could inject more moisture and cool the mid-level temps, weakening the cap over the plains, while at the surface, outflow boundaries pushing from mountain convection will collide with existing boundaries from yesterday giving just enough lift to break the cap.

Storms that do form will be able to take advantage of close to 3cm of precipitable water and lack of steering winds could hold them in place. Storms could also ride the boundaries, leaving pure chaos on the plains. Some pulse storms that reach decent height could also produce some hail today, though wind and minor flooding appear to be the main threats.

I'll be working at the flood center today, so call if you need a nowcast.


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