Just to reiterate -- from my understanding, the "400,000" for outages in Oklahoma refers to the number of customers affected. Just to guess, consider that 75% of those are homes (apartments, etc; the remainder being businesses), and take an average of 3 people per household... That puts the total number of people w/o power in Oklahoma near 1 million.
OGE SystemWatch shows 226,176 customers without power in their area (central OK), and
PS-AEP (which covers Tulsa) shows 200,000 customers w/o power in their area. I sure there are plenty more rural co-op electric services that are down, so the statewide "customers affected" number may be nearing 500,000. FWIW, the local TV media in OKC are saying that this is either the largest power outage event in Oklahoma history, or this is the largest power outage event in OG&E history.
The sheer amount of precipitation that has fallen in some areas amazes me. For example, KOKC (Oklahoma City airport) recorded 0.86" yesterday, and 2.39" from 06z-18z today. That's 3.25" liquid-equivalent precipitation in 36 hours, with the vast majority of that fell when the surface temperature was below freezing. Interestingly, KOKC recorded 1.99" of liquid precipitation between 6-12z today. Now, if only the OK Mesonet sites had heated rain gauges...
Edit: climate summary for OKC gives daily precip of 1.18" today so far... So, that 1.99" between 6-12z must have been not passed the data quality check (not surprising, since I can't imagine 2" of rain fell in 6 hrs overnight, given the evolution of everything I watched on radar).