The article doesn't mention anything about the physical dimensions or the power requirements, but I wonder if putting this on a mobile platform would be at all practical. It's one thing to put them on common storm paths, but imagine aiming a few of these at different axis at a tornado. Being able to analyze the motion of individual bits of debris in a tornado would teach us a lot, I think.
The radar they are using is a component of the ballistic defense network. Unfortunately, there are a lot of 'mid-course radars' in those schemes. On a hunch, I think they're referring to this one http://www.globalsecurity.org/space/systems/sbx.htm.
That figure is almost certainly the peak pulse power, not the actual supply requirements. Modern radar almost all operate by firing very very short pulses at relatively low repetition rates[1]
I don't know about the system in question (and if it's still a prototype, it's going to be bigger than it could be), but I think I've heard of systems with similar pulse power being installed in (fighter) aircraft.
Fighter nose radars are still in the kilowatt range. Those systems are also rather light (~700lbs all totaled, not counting coolant). There may be pylon-mounted systems that get to the upper end of that (>100kW). High power airborne radars are typically carried by larger, purpose-built platforms such as the E-2C, E-3, and E-8.
