768
FXXX10 KWNP 261231
DAYTDF

:Product: 3-Day Forecast
:Issued: 2026 Apr 26 1230 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC contact on the Web
# http://www.swpc.noaa.gov/wwire.html
#
#             3-Day Forecast
#
A. NOAA Geomagnetic Activity Observation and Forecast

The greatest observed 3 hr Kp over the past 24 hours was 4 (below NOAA
Scale levels).
The greatest expected 3 hr Kp for Apr 26-Apr 28 2026 is 5.00 (NOAA Scale
G1).

NOAA Kp index breakdown Apr 26-Apr 28 2026

             Apr 26       Apr 27       Apr 28
00-03UT       2.67         3.67         2.67
03-06UT       3.67         3.00         2.67
06-09UT       2.67         2.67         2.33
09-12UT       3.67         2.33         2.00
12-15UT       3.00         2.00         2.00
15-18UT       3.00         2.33         1.67
18-21UT       3.33         3.33         2.00
21-00UT       5.00 (G1)    3.33         2.00

Rationale: Isolated G1 (Minor) geomagnetic storming conditions are
likely on 26 Apr in response to +CH HSS influence combined with the
anticipated arrival of the glancing CMEs from 23-24 Apr.

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    5%      5%      5%

Rationale: No S1 (Minor) or greater solar radiation storms are expected.
No significant active region activity favorable for radiation storm
production is forecast.

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 26 2026 0023 UTC.

Radio Blackout Forecast for Apr 26-Apr 28 2026

              Apr 26        Apr 27        Apr 28
R1-R2           55%           55%           55%
R3 or greater   10%           10%           10%

Rationale: R1-R2 (Minor-Moderate) radio blackouts are likely, with a
slight chance for R3 (Strong or greater) events through 28 Apr.