During last 24 hours solar wind stream buffeted Earth's magnetic field causing geomagnetic storms around the poles. Geomagnetic conditions were short lived reaching G1 - Minor geomagnetic storm levels (Kp=5). At those levels weak power grid fluctuations can occur, minor impact on satellite operations is possible, migratory animals are affected at this and higher levels and aurora is commonly visible at high latitudes.
At about 05:13 UTC on August 4, Phi angle became positive (away) and total field, temperature and wind speed began to rise. Wind speed rose from 350 km/s to a maximum of 586 km/s at 23:00 UTC.
The Bz component turned mostly southward for several hours and reached -13 nT by 20:25 UTC. This sequence of events brought unsettled levels of activity and a single period of minor storm conditions between 15-18 UTC.
During the same period, major storm levels were observed at high latitudes.
Geomagnetic field activity is expected to be at mostly quiet levels in the absence of any transient solar wind features. Recurrent coronal hole high speed streams are expected to bring unsettled to active conditions on August 5, 6 and 8, August 18-19, 21-23 and 31.
There is a slight chance for minor storm conditions on August 5 and again on August 31.
Space Weather Message Code: ALTK05
Serial Number: 726
Issue Time: 2013 Aug 05 0301 UTC
ALERT: Geomagnetic K-index of 5
Threshold Reached: 2013 Aug 05 0300 UTC
Synoptic Period: 0300-0600 UTC
Active Warning: Yes
NOAA Scale: G1 - Minor
Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.
Featured image credit: SWPC - Aurora Forecast - Ovation prime model for August 5, 2013
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