<AUR>.Forecast Discussion

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