Big hail near Dallas, April 11

A major hail event occurred in the north suburbs of Dallas on Monday, April 11.  Some media I thought worth saving are captured below.  [Reminders: more than anything, this is archive of images and links that I might use in future classes.  I may add more later, or delete some of these.  If you have any sources that you think complete or improve on this set, please do share.]

Let’s start with the geography of the event:

The Severe Thunderstorm Warning that included Wylie, focus of some of the videos below:



Slow-motion video of baseball or softball hail crashing into a pool:

Additional good ones:



I don’t know how big this person’s hand is, but does it really matter?

Additional good ones:


  • The focusing mechanism for convection: a surface low, frontal boundary and dryline.  The WPC’s surface analysis at 1800 UTC:
  • The full complement of upper air charts for 1200 UTC (11th) and 0000 UTC (12th) is available via the Storm Prediction Center’s archive.
  • A 9-h forecast sounding from the 4km NAM for 2100 UTC (model initialized at 1200 UTC).  Over 3000 J/kg of CAPE, no matter how you calculate it!
  • And if model soundings aren’t your thing, the observed, pre-event FWD sounding at 1800 UTC.  But note that in this case, there’s a 2500 J/kg difference between surface-based and mixed-layer CAPE; the high surface dewpoint may be anomalous.
  • A regional radar loop that honestly isn’t that breathtaking, but illustrates the isolated supercell nature of this hail producer.
  • At one point, about 2200 UTC, the storm had a textbook high-precipitation supercell look.  Upper left and color bar: reflectivity at the lowest elevation angle.  Lower left: storm-relative velocity.  Upper-right: VIL (the scale maxes out at 80 kg/m2, but I found a value of 121!!!).  Lower right: radar-estimated maximum hail size, with one pixel indicating 2.98-inch size.  Probably one too many significant figures there, but I digress.