roduct: 3-Day Forecast
:Issued: 2026 Aug 28 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 1 (below NOAA
Scale levels).
The greatest expected 3 hr Kp for Aug 28-Aug 30 2026 is 5.67 (NOAA Scale
G2).

NOAA Kp index breakdown Aug 28-Aug 30 2026

             Aug 28       Aug 29       Aug 30
00-03UT       2.33         5.67 (G2)    3.67     
03-06UT       2.67         4.67 (G1)    3.33     
06-09UT       4.00         4.00         3.00     
09-12UT       4.00         3.00         3.00     
12-15UT       4.67 (G1)    2.33         3.00     
15-18UT       5.00 (G1)    2.67         2.00     
18-21UT       4.67 (G1)    2.67         3.33     
21-00UT       5.67 (G2)    3.00         3.33     

Rationale: G1 (Minor) storm levels are likely due to the onset of
positive polarity CH HSS effects. Later on 28 Aug, G2 (Moderate) storm
levels are likely due to additional disturbances caused by the
anticipated arrival of the CMEs that left the Sun on 25-26 Aug. G1 to G2
storm levels are likely to persist through 29 Aug before waning
conditions are expected on 30 Aug.

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 Aug 28-Aug 30 2026

              Aug 28  Aug 29  Aug 30
S1 or greater   10%     10%     10%

Rationale: here is a slight chance for the greater than 10 MeV proton
flux to reach S1 (Minor) storm levels through 30 Aug, mostly due to the
potential for activity from Region 4513.

C. NOAA Radio Blackout Activity and Forecast

No radio blackouts were observed over the past 24 hours.

Radio Blackout Forecast for Aug 28-Aug 30 2026

              Aug 28        Aug 29        Aug 30
R1-R2           45%           45%           45%
R3 or greater   10%           10%           10%

Rationale: There is a chance for isolated R1/R2 (Minor-Moderate) radio
blackouts, with a slight chance for an isolated R3 (Strong) event
through 30 Aug primarily due to the current potential and flare history
of Region 4513.


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