If it was in Mother Nature's playbook, it was used against parts of Nebraska Tuesday evening: Torrential rain, constant lightning, near-hurricane-force winds, tornadoes, and tennis ball-sized hail...
Pretty much all at the same time.
Let's start with the torrential rain as I was wide-eyed watching the rainfall numbers come in from Omaha.
The storm began with quite the punch, bringing a burst of rainfall and a gust of wind that was clocked at 72 mph!
The rain just kept going from there, which included jaw-dropping rainfall rates that saw over a half-inch of rain (0.53") fall in 3 minutes! That's 0.01" of rain per 3.4 seconds.
Here is their full rundown of rain at Omaha's airport, with the accumulating total listed first (all times CDT):
- 4:36: Rain begins
- 4:40: Wind gust reported of 72 mph
- 4:52: 1.15" of rain (in 16 minutes!). Hail at 1" diameter
- 4:57: 1.71" (+0.56" in 5 minutes)
- 5:00: 2.24" (+0.53" in 3 minutes!)
- 5:09: 2.42" (+0.18" in 9 minutes)
- 5:14: 2.43"
- 5:27: 2.53"
- 5:52: 2.67"
- 6:19: 2.75"
- 6:25: 3.14" (0.39" in 6 minutes)
- 6:44: 4:08" (0.94" in 19 minutes)
- 6:52: 4.11"
- 7:52: 4.41"
- 8:52: 4.57"
- (Light to moderate rain for next 4 hours)
- 1:53 am: 5.30" -- storm total in 9 hours and 17 minutes.
That's right -- 5.30" of rain in just over 9 hours. To compare, that's roughly Portland's entire monthly rainfall average for December!
So an unfathomable amount of rain for us, but it wasn't just the rain and wind that wreaked havoc, but the hail as well. Some places in northeastern Nebraska reported tennis-ball sized hail!
Combine that with the extreme outflow winds from the storm gusting 50-80 mph and it takes sand blasting to a whole new level:
And here is video from the hail storm showing tennis ball-sized hail stones -- this taken from Norfolk, Nebraska: (Warning, there is a little off-color language in there)
What makes the hail so large?
In case you missed it from my hail blog earlier this week, it's intense updrafts and the altitude of the storms that help the hailstones grow so large. The updrafts push raindrops up into the higher reaches of the cloud where it's well below freezing and the raindrops freeze into an ice pellet.
The pellet eventually gets too heavy for the tip of the updraft and falls back toward the Earth, getting wet again as it falls through more raindrops. It encounters the stronger updraft at the base of the cloud and gets shot upward again into the sub-freezing temperatures where the water on the pellet freezes again, adding another layer of ice. That pellet falls, gets wet, hits the updraft, goes back up, and grows again with another layer of ice.
This process repeats until the hail stone is heavier than the updraft can support it and it finally falls to the ground. The stronger the updraft, the larger the hailstone can grow. It's said a 56 mph updraft will support a golf-ball-sized hailstone, so the updrafts in these particular hailstorms were extreme!