Yeah, you can read in the comments and you have multiple people saying "look, I googled for information about it and found articles". That's not how we learn initially about events. 95+% of Americans get their news from top headlines and TV clips. You have to know something is happening to start googling for more information.
Then there's the timing of the tweet vs headlines. I can't see the date on the wapo because of their paywall (guessing the 13th from the link), but I can on the NYT. It's the same date as the tweet, and the tweet was at 7:10AM and the article was at like 11PM if Google is accurate. Not that it's because of this tweet, but I can find multiple variants of the same article all coming out in the last ~12-18 hours across media outlets. Having a hard time trying to find exact dates where the flooding started, this suggests it was bad already on Wednesday:
https://www.accuweather.com/en/weat...lood-risk-in-upper-midwest-this-week/70007663
Also, if you look at the main pages, it's not leading news at all, which makes no sense unless you don't give two shits about the tragedy and horrors of fellow countrymen and instead are excited about mob boss killer trials (CNN) and the NZ attacks (NYT). If you scroll 2/3 of the way down the NYT page, you can find the one little entry for it. Web user data says that few scroll that far even for actual content. Likely less for "headlines". Yes, that entry is top under "US", but why wouldn't that be the top on the main page as well?