From the Washington Post's Capitol Weather Gang:
Giant sunspot shoots out intense, X-class solar flare
UPDATE, 3:30 p.m.: NOAA’s Space Weather Prediction Center (SWPC) just posted the following:
The R3 (Strong) Radio Blackout today at 12:49 EDT (1649 UTC) was accompanied by an earth-directed CME. Hampered by limited observations of the event, SWPC forecasters are now anticipating the passage of the [coronal mass ejection] around 1:00 a.m. EDT, Saturday, July 14. G1 (minor) Geomagnetic Storm activity is expected to then ensue through the rest of the day.
SpaceWeather.com thinks it's more serious than the gang:
In short, NOAA is predicting minor effects from this space weather event - no major impacts on the power grid or satellites anticipated - although we remind you forecasting space weather is difficult and surprises are possible. Sky watchers in northern U.S. (and high latitudes) may have an opportunity to see aurora late Friday night into early Saturday morning.
Original post, from 2:30 p.m.: A massive sunspot region facing Earth - known as 1520 - has unleashed a large solar flare. NOAA’s Space Weather Prediction Center says the flare is rated an X1.4. This type of flare is considered “strong” and can cause a blackout of high frequency radio communication on the sunlit side of Earth for one to two hours.
X-FLARE! Big sunspot AR1520 unleashed an X1.4-class solar flare on July 12th at 1653 UT. Because this sunspot is directly facing Earth, everything about the blast was geoeffective. For one thing, it hurled a coronal mass ejection (CME) directly toward our planet. According to a forecast track prepared by analysts at the Goddard Space Weather Lab, the CME will hit Earth on July 14th around 10:20 UT (+/- 7 hours) and could spark strong geomagnetic storms. Sky watchers should be alert for auroras this weekend....MORE