There are a lot of modern facilities providing solar flare predictions, many are old and many are new. Some are space based and a lot are ground based (radio te

There are a lot of modern facilities providing solar flare predictions, many are old and many are new. Some are space based and a lot are ground based (radio telescopes and coronagraphs) Government agencies amalgamate data from all the sources to come up with the best predictions. We always have more than 12 hours to prepare after spotting something from surface on the Sun, the accuracy of predictions improves as time goes by, the 20 minute mark is generally the time it takes for a fast CME to go from L1 Lagrange point to Earth. L1 is where multiple aging solar observatories collect insitu data, but we usually know before then if a strong event is Earth directed.