roduct: 3-Day Forecast
:Issued: 2026 Apr 26 0030 UTC
# Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction 
Center
#
A. NOAA Geomagnetic Activity Observation and Forecast

The greatest observed 3 hr Kp over the past 24 hours was 3 (below NOAA
Scale levels).
The greatest expected 3 hr Kp for Apr 26-Apr 28 2026 is 4.67 (NOAA Scale
G1).

NOAA Kp index breakdown Apr 26-Apr 28 2026

             Apr 26       Apr 27       Apr 28
00-03UT       4.67 (G1)    3.67         2.33     
03-06UT       4.33         3.00         2.00     
06-09UT       3.33         2.67         2.00     
09-12UT       3.33         2.33         2.00     
12-15UT       2.33         2.00         2.33     
15-18UT       2.33         2.33         2.00     
18-21UT       3.00         3.33         2.00     
21-00UT       3.33         3.33         2.00     

Rationale: Isolated G1-G2 (Minor-Moderate) geomagnetic storming
conditions are possible (G1 likely with a chance for G2)early 26 Apr in
response to the arrival of the glancing CMEs.

B. NOAA Solar Radiation Activity Observation and Forecast

Solar radiation, as observed by NOAA GOES-18 over the past 24 hours, was
below S-scale storm level thresholds.

Solar Radiation Storm Forecast for Apr 26-Apr 28 2026

              Apr 26  Apr 27  Apr 28
S1 or greater   10%     10%     10%

Rationale: There is a chance to exceed the S1 (Minor) solar radiation
storm thresholds due to the flare potential of Region 4419 further
beyond the western limb, and Region 4420 near the central solar
meridian.

C. NOAA Radio Blackout Activity and Forecast

Radio blackouts reaching the R1 levels were observed over the past 24
hours. The largest was at Apr 25 2026 0759 UTC.

Radio Blackout Forecast for Apr 26-Apr 28 2026

              Apr 26        Apr 27        Apr 28
R1-R2           55%           55%           55%
R3 or greater   15%           15%           15%

Rationale: R1-R2 (Minor-Moderate) radio blackouts are likely, with a
slight chance for R3 (Strong or greater) events through 28 Apr,
primarily driven by the complexity of Regions 4420, 4423, and 4425.


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