Official Space Weather Advisory issued by NOAA Space Environment Center Boulder, Colorado,


2000 May 09 at 02:06 p.m. MDT (2000 May 09 2006 UT)


Summary For May 1-7 An R2 (moderate) radio blackout occurred on May 4 at 05:08 a.m. MDT
(2000 May 4 1108 UT) due to a large solar flare. R2 radio blackouts normally result in the following
effects on the sunlit side of Earth: limited blackout of HF radio communication signals with loss of
radio contact for tens of minutes for mariners and en route aviators, and degradation of low frequency
navigation signals for tens of minutes affecting maritime and general aviation positioning. Isolated R1
(minor) radio blackouts were observed during May 1 – 5.

Outlook For May 10-16 A category G2 (moderate) geomagnetic storm is expected during May 11 –
13 due to a coronal mass ejection observed on May 8. G2 storms normally affect high latitude power
systems. Spacecraft operations are also affected to the extent that corrective actions are required, and
changes in atmospheric drag affect orbit predictions. In addition, G2 storms cause fading of HF radio
communication signals at higher latitudes, and the aurora can be seen as low as 50 degrees latitude.
Isolated R1 radio blackouts are also possible during the period.