Product: Forecast Discussion Issued: 2013 Sep 15 0030 UTC Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center Solar Activity .24 hr Summary... Solar activity remained at very low levels during the period. Slight decay was observed in Region 1839 (S12W83, Hrx/alpha) as it approached the west limb. Region 1841 (S06E28, Cso/beta) was relatively stable. Two filaments disappeared in the southwest quadrant, however no Earth directed coronal mass ejections have been noted in coronagraph imagery. .Forecast... Solar activity is expected to be very low through the period (Sep 15-17) with a slight chance for a C-class flare. Energetic Particle .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 increase to normal to high levels on Sep 15-16 due to coronal hole high-speed stream (CH HSS) effects. The greater than 10 MeV proton flux at geosynchronous orbit is expected to be at background levels during the period (Sep 15-17). Solar Wind .24 hr Summary... A coronal hole high speed stream continued to affect geospace. Wind speed began near 550-600 km/s and had decreased to near 480 km/s by 14/1900 UTC. Bt also decreased from near 5 nT to about 2 nT and Bz ranged from 4 nT to -3 nT. The phi angle was predominantly negative (toward) throughout the period. .Forecast... Solar wind speed is expected to slowly decrease to nominal levels on Sep 15. On Sep 16, another increase is expected in response to a positive polarity CH HSS which is expected to persist through the end of the period. Geospace .24 hr Summary... The geomagnetic field was quiet to active due to CH HSS activity. .Forecast... Geomagnetic field activity is expected to begin at mostly quiet levels on Sep 15. By Sep 16, quiet to unsettled conditions are expected with active periods likely and a slight chance for minor storm (G1) conditions as a positive polarity CH HSS becomes geoeffective. Unsettled conditions, with a chance for active levels, are expected the following day (Sep 17).
Posted on: Sun, 15 Sep 2013 08:47:36 +0000
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