:Product: Forecast Discussion :Issued: 2018 Sep 22 0030 UTC # Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center # Solar Activity .24 hr Summary... Solar activity was very low. The visible disk was spotless and no Earth-directed CMEs were observed in available satellite imagery. .Forecast... Solar activity is expected to be at very low levels on 22-24 Sep. Energetic Particles .24 hr Summary... The greater than 2 MeV electron flux reached high levels this period with a peak flux of 10,600 pfu at 21/2200 UTC. The greater than 10 MeV proton flux was steady at background levels throughout the period. .Forecast... The greater than 2 MeV electron flux is expected to reach high levels on day one (22 Sep), and decrease to moderate levels on days two and three (23-24 Sep) due to positive polarity CH HSS influence. The greater than 10 MeV proton flux is expected to persist at background levels. Solar Wind .24 hr Summary... The solar wind environment reflected ambient background conditions until late in the period. After 21/1500 UTC, an enhancements was observed in total magnetic field strength, with a peak of 11 nT observed at 21/2147 UTC. The Bz component was predominantly southward during this time, reach a maximum southward deflection of -10 nT. Phi angle became variable during this time which suggested a possible interaction with a solar sector boundary crossing. Wind speeds remained below 400 km/s throughout the period. .Forecast... Solar wind parameters are expected to continue at current levels until the anticipated arrival of a recurrent, positive polarity CH HSS late on day one (22 Sep). This CH HSS enhancement is expected through day two (23 Sep) and to become further enhanced on day three (24 Sep) as influence from a negative polarity CH HSS persists. Geospace .24 hr Summary... The geomagnetic field was mostly quiet until late in the day when G1 (Minor) storm levels were reached due to prolonged periods of southward Bz. .Forecast... The geomagnetic field is expected to be at mostly quiet to active levels, with isolated periods of G1 (Minor) storm levels expected, over day one (22 Sep) due to a SSBC ahead of influence from a recurrent, positive polarity CH HSS. Unsettled to G1 (Minor) storm levels are likely on day two (23 Sep) as persistent CH HSS effects continue. Day three (24 Sep)is expected to be at quiet to active levels due to the anticipated arrival of an additional negative polarity, CH HSS feature.