roduct: 3-Day Forecast
:Issued: 2026 May 11 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 2 (below NOAA
Scale levels).
The greatest expected 3 hr Kp for May 11-May 13 2026 is 2.67 (below NOAA
Scale levels).

NOAA Kp index breakdown May 11-May 13 2026

             May 11       May 12       May 13
00-03UT       1.67         1.67         1.67     
03-06UT       2.67         1.67         2.67     
06-09UT       2.67         1.33         2.67     
09-12UT       1.67         1.33         2.33     
12-15UT       1.33         1.33         2.33     
15-18UT       1.33         0.67         2.00     
18-21UT       2.00         1.67         2.33     
21-00UT       2.67         1.67         2.67     

Rationale: No G1 (Minor) or greater geomagnetic storms are expected.  No
significant transient or recurrent solar wind features are forecast.

B. NOAA Solar Radiation Activity Observation and Forecast

Solar radiation, as observed by NOAA GOES-19 over the past 24 hours, was
below S-scale storm level thresholds.

Solar Radiation Storm Forecast for May 11-May 13 2026

              May 11  May 12  May 13
S1 or greater   20%     20%     20%

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 R2 levels were observed over the past 24
hours. The largest was at May 10 2026 1339 UTC.

Radio Blackout Forecast for May 11-May 13 2026

              May 11        May 12        May 13
R1-R2           45%           45%           45%
R3 or greater   20%           20%           20%

Rationale: There exists a chance for R1-R2 (Minor-Moderate) radio
blackouts, with a slight chance for R3 (Strong), over 11-13 May.


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