Summary For May 22-28

A category G3 (strong) geomagnetic storm occurred from 6:00 p.m. to midnight MDT on 23 May (2000 May 24 0000 - 0600UT). The storm was the result of a coronal mass ejection passage at Earth. Category G3 storms adversely affect various ground-based, space-based, and other types of systems. Space-based system effects include surface charging on satellite components, increased atmospheric drag on satellites, and satellite orientation problems that require corrective actions.

Ground-based system, i.e. electrical power grid, effects include high "gas in oil" transformer readings, voltage corrections required, and false alarms triggered on protection systems. Other G3 storm effects include intermittent satellite and low-frequency navigation problems, intermittent HF radio reception, and aurora seen as low as the middle latitudes.

Two category R1 (minor) radio blackouts occurred on 24 May due to solar flares, which resulted in the following effects on the sunlit side of Earth: weak degradation of HF radio communications with occasional loss of radio contact for mariners and en route aviators, and low-frequency navigation signals degraded for brief intervals affecting maritime and general aviation positioning.

Outlook For May 31-June 6

There is a chance for a category G1 (minor) geomagnetic storm on May 31 due to high-speed solar winds associated with a coronal hole. G1 storms normally cause weak power grid fluctuations and minor impacts on satellite operations.

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