Space weather reached moderate levels due to category R2 (moderate) radio blackouts and a category G2 (moderate) geomagnetic storm. A total of three category R2 radio blackouts occurred during July 19 - 21 due to large solar flares.

Category R2 radio blackouts typically result in the following effects on the sunlit portion of Earth: limited blackout of high-frequency radio communication signals resulting in loss of 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.

A category S1 (minor) solar radiation storm was detected by the NOAA GOES spacecraft during July 22 - 23 and resulted in minor impacts on high-frequency radio communications in the polar regions. Category G2 (moderate) geomagnetic storm conditions occurred on July 20 due to a CME (coronal mass ejection) passage at Earth.

Moderate geomagnetic storm conditions normally result in some or all of the following system effects: voltage alarms are possible on high latitude power systems (but tripping is not likely); spacecraft operations require corrective actions by ground control and changes in atmospheric drag affect orbital predictions; and high-frequency radio communication signals fade at high latitudes.

Outlook For July 26-August 1

Category R1 (minor) to R2 (moderate) radio blackouts are expected during the period with effects similar to those mentioned above. Category G1 (minor) geomagnetic storm conditions are expected during July 27 - 28 following a CME observed earlier today. G1-level geomagnetic storms will normally result in minor impacts on satellite operations and high-latitude power systems.

Data used to provide space weather services are contributed by NOAA, USAF, NASA, NSF, USGS, the International Space Environment Services and other observatories, universities, and institutions. More information is available at SEC's Web site http://sec.noaa.gov