Product: Forecast Discussion Issued: 2013 Sep 19 1230 UTC Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center Solar Activity .24 hr Summary... Solar activity was low. A sole low level C-class flare occurred during the period; a C1 at 19/0817 UTC which appears to be sourced from a region that has not yet rotated around the East limb. At least two CMEs were observed coming off of the sun during the period with source locations all in the southeast quadrant of the solar disk or around the East limb. Initial analysis of all events during the period suggests that no Earth directed CMEs occurred. .Forecast... Solar activity is expected to be very low with a chance for a C-class flare on days one, two, and three (19 Sep, 20 Sep, 21 Sep). Energetic Particles .24 hr Summary... The greater than 2 MeV electron flux at geosynchronous orbit was at normal levels. The greater than 10 MeV proton flux at geosynchronous orbit was at background levels. .Forecast... The greater than 2 MeV electron flux at geosynchronous orbit is expected to be at normal to moderate levels for Sep 19. A chance for high levels exists on Sep 20-21 in response to a coronal hole high-speed stream (CH HSS). The greater than 10 MeV proton flux at geosynchronous orbit is expected to continue at background levels. Solar Wind .24 hr Summary... Solar wind, as measured by the ACE spacecraft, indicated the continued presence of a positive-polarity CH HSS. Solar wind speeds remained relatively steady in a range between 550 and 600 km/s. However, Total IMF decreased from near 10 nT at the beginning of the period to less than 5nT at the end. The maximum southward component of Bz was near -4nT for brief periods. The phi angle remained at a positive-polarity (away) orientation. .Forecast... Enhanced solar wind conditions from CH HSS effects should persist on Sep 19. CH HSS effects should begin to subside on Sep 20 and return to background levels on Sep 21. Geospace .24 hr Summary... The geomagnetic field was quiet to unsettled. .Forecast... The geomagnetic field is expected to be at quiet to unsettled levels on days one and two (Sep 19-20) as a result of CH HSS effects. Day three (Sep 21) should see a return to mostly quiet conditions after CH effects wane.
Posted on: Thu, 19 Sep 2013 13:19:24 +0000