Tuesday, July 19, 2011

Storm chances this afternoon/evening

Starting to notice a few cumulus clouds building late this morning and those will probably continue to build as we go into the afternoon.  There is a weak lake breeze that is beginning to develop as a northeast wind comes off of Lake Michigan.  This also combines with another weak boundary from the cool front that moved in yesterday.  Behind this weak front the heat and humidity has created a very unstable airmass with CAPE values (convective available potential energy or how much energy is available in the atmosphere) nearing 5000 J/KG (that's pretty high).  We're currently watching storms that have developed right around the Twin Cities thanks to that stationary front but also a little support from the mid-levels.  The storm in the Twin Cities will likely move southeast towards the high CAPE values, however, the further south it gets the further away it becomes from any upper level support. 

Should thunderstorms get going across the area this afternoon the potential will exist for them to develop rapidly due to the very unstable airmass in place.  Damaging winds and heavy rainfall would be the primary concerns.  Radar and visible satellite trends will be monitored throughout the afternoon to see if the any outflow boundaries from the storms to the northwest along with the lake breeze are able to interact with each other. 

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