:Product: Forecast Discussion
:Issued: 2026 Apr 21 0030 UTC
# Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center
#
Product: Forecast Discussion
Issued: 2026 Apr 21 0030 UTC
Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction
Center

.24 hr Summary...
Solar activity reached low levels, where the largest flare of the
reporting period was a C1.6 flare at 20/1514 UTC from off the eastern
limb around S08, likely associated with a simultaneous 245 MHz radio
burst; Solar Orbiter science data indicates that a new active region is
rotating onto the Earth-visible disk in that vicinity, however there is
insufficient data to do a formal analysis currently. Region 4419
(N14W24, Eho/beta-gamma) exhibited minor growth in its trailer spots,
but its leader spot consolidated so the overall area did not change
appreciably. Region 4415 (S18W85, Hsx/alpha) remained unchanged and was
inactive.

No Earth directed CMEs were observed in coronagraph imagery.

.Forecast...
Solar activity is expected to be at very low levels, with a chance for
isolated C-class activity on 21-23 Apr, primarily due to the flare
potential from Region 4419 and limb activity.


Energetic Particle

.24 hr Summary...
The greater than 2 MeV electron flux at geosynchronous orbit reached
high levels at 19/1925 UTC with a maximum reading of 1,187 pfu. The
greater than 10 MeV proton flux was at background levels.

.Forecast...
The greater than 2 MeV electron flux is expected to be at moderate to
high levels on 21-23 Apr. The greater than 10 MeV proton flux is
expected to continue at background levels on 21-23 Apr.


Solar Wind

.24 hr Summary...
Solar wind parameters were at nominal/background levels at the beginning
of the reporting period then started becoming enhanced at approximately
20/0545 UTC. Total magnetic field (Bt) reached a max of 10 nT at 20/1330
UTC. The north-south component (Bz) had two sustained periods of south
deflection, reaching maximums of -8 nT both periods. The wind speed
slowly increased from ~415 km/s to a max of ~570 km/s at 20/1430 UTC,
where it largely stayed for the remainder of the reporting period______.
Phi was mostly in a negative orientation (towards the Sun), with
isolated oscillations into a positive position.

.Forecast...
Weakening enhanced solar wind conditions are expected on 21 Apr as the
CH HSS continues to move from its geoeffective position. A return to
mostly nominal conditions is expected 22-23 Apr.


Geospace

.24 hr Summary...
The geomagnetic field went from Quiet to G1 (Minor) storming levels due
to sustained periods of negative Bz during the ongoing -CH HSS
conditions.

.Forecast...
Mostly quiet to unsettled levels are expected on 21 Apr, with isolated
active conditions possible and a slight chance for G1 (Minor) storm
levels,as HSS effects diminish. Mostly quiet levels are expected, with
possible unsettled periods, on 22 Apr as CH HSS influence dissipates,
with predominantly quiet levels on 23 Apr.