NWS definition:
Shelf Cloud – A low, horizontal wedge-shaped arcus cloud, associated with a thunderstorm gust front (or occasionally with a cold front, even in the absence of thunderstorms). Unlike the roll cloud, the shelf cloud is attached to the base of the parent cloud above it (usually a thunderstorm). Rising cloud motion often can be seen in the leading (outer) part of the shelf cloud, while the underside often appears turbulent, boiling, and wind-torn.Enjoy the pics!
What kind of clouds do we have here? #Muncie @JimOBrienWX @ToddKlaassen @PaulPoteet @randyollis @ChuckWTHR pic.twitter.com/3g0nf4sWa3
— Cameron Ridle (@CameronRidle) September 18, 2015
RT @nsc_doc: Carmel view pic.twitter.com/Ke51LOC3UN
— NWS Indianapolis (@NWSIndianapolis) September 18, 2015
Nice looking pic of the shelf cloud Aaron! RT @AaronWxDavis: Cool looking shelf cloud this morning in Muncie. #INwx pic.twitter.com/I54Ao2trBx
— NWS Indianapolis (@NWSIndianapolis) September 18, 2015
Gorgeous! RT @kc9qha: Beautiful shelf cloud passing over the north side of Indy. #INwx pic.twitter.com/zsHhnNwxro
— NWS Indianapolis (@NWSIndianapolis) September 18, 2015
RT @purdueturfy: here is a good shelf pic at Sagamore in Noblesville. pic.twitter.com/csJ2n5pfEt
— NWS Indianapolis (@NWSIndianapolis) September 18, 2015
This one is from Helen Hewitt Riley on Facebook.
