Space Weather Forecast Discussion
Forecast Discussion
Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center
Issued: 2018 Apr 21 1230 UTC

Solar Activity
.24 hr Summary...
Solar activity was very low. Slight growth was observed in Region 2706 (N04E50, Dao/beta) which produced multiple low-level B-class flares. The largest was a B5 flare at 20/1704 UTC. No Earth-directed CMEs were observed in available coronagraph imagery.
Solar activity is expected to be very low, with a slight chance for an isolated C-class flare, throughout the forecast period (21-23 Apr).

Energetic Particle
.24 hr Summary...
The greater than 2 MeV electron flux reached high levels this period with a peak flux of 2,620 pfu observed at 20/2115 UTC. The greater than 10 MeV proton flux was steady at background levels.
The greater than 2 MeV electron flux is expected to reach high levels each of the next three days (21-23 Apr) and the greater than 10 MeV proton flux is expected to persist at background levels throughout the forecast period.

Solar Wind
.24 hr Summary...
Solar wind parameters continued to be enhanced through the period under the influence of a negative polarity CH HSS. Solar wind speed increased from approximately 480 km/s to near 600 km/s. Total field decreased from 15 nT to near 6 nT by 20/1925 UTC. The Bz component reached a maximum southward deflection of -12 nT at 20/1218 UTC. Phi angle was oriented in a negative (towards) solar sector.
Solar wind parameters are expected to remain enhanced through midday on day two (21-22 Apr) due to the continued influence of a negative polarity CH HSS. A slow decrease to near-background solar wind levels is expected over the latter half of day two through day three (22-23 Apr) as CH HSS influence subsides and a nominal solar wind regime prevails.

.24 hr Summary...
The geomagnetic field was at quiet to G1 (Minor) storm levels due to CH HSS activity. G1 (Minor) storm levels were observed during the 20/1800-2100 UTC period.
The geomagnetic field is expected to be at quiet to active levels for the rest of the UTC day on day one (21 Apr) as CH HSS effects continue. Quiet to unsettled conditions are expected on day two (22 Apr) as CH HSS influence wanes and generally quiet conditions are expected to prevail on day three (23 Apr) with the return of a nominal solar wind regime.
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