M9-class Long-Duration Solar X-ray Flare (2012-Jan-23 0359 UTC)

According to NASA and NOAA Spaceweather Radio Propagation sources, this is NOT going to continue as a minor occurrence and has so far affected 20 meters through 6 meters, and 2 Meters through 1.2Ghz. (14Mhz and up to 29.995Mhz,50.00Mhz through 54.00Mhz, 144.00 to 148.00Mhz, 223.00 to 225.000Mhz, 420 - 450Mhz, and higher)

Amateur repeaters on the VHF and UHF bands have become almost deaf across the nation early this morning, and will see difficulties in operations until this storm is over. The band conditions for the listed frequencies will range from useless to minimally useful. This goes to say that the Minimum Useful Frequency and Maximum Useful Frequency (MUF) will be affected for sure.

Understanding LF & HF Propagation: FREE E-Book

G0KYA and G3NYK over at RSGB have written an E-Book about LF and HF Propagation. They decided to make this detailed book available for free. Here is the original link to G0KYA's site 

To download this FREE PDF file, click on the link for Understanding LF & HF Propagation
Sponsored by the RSGB Propagation Studies Committee.