Sunspots 684 and 687 pose a threat for for M-class solar flares.
Yesterday it was barely visible; today it's five times wider than Earth. Sunspot 684 is growing remarkably fast. Witness this 24-hour animation from the Solar and Heliospheric Observator (SOHO):
Sunspot 684 is the one near the middle. When sunspots evolve so rapidly, their magnetic fields can become unstable and erupt. This active region merits watching as a possible source of solar flares.