Subj : 3 Day Space Weather Forecast
To   : All
From : Sean Dennis
Date : Sun Jun 28 2026 00:19:02

:Product: 3-Day Forecast
:Issued: 2026 Jun 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 3 (below NOAA
Scale levels).
The greatest expected 3 hr Kp for Jun 28-Jun 30 2026 is 4.33 (below NOAA
Scale levels).

NOAA Kp index breakdown Jun 28-Jun 30 2026

             Jun 28       Jun 29       Jun 30
00-03UT       3.00         1.67         1.67     
03-06UT       3.67         1.33         3.00     
06-09UT       3.67         1.33         4.00     
09-12UT       3.00         1.33         4.33     
12-15UT       2.00         1.33         4.33     
15-18UT       1.67         1.33         3.67     
18-21UT       2.67         1.67         3.33     
21-00UT       2.67         1.67         1.67     

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-18 over the past 24 hours, was
below S-scale storm level thresholds.

Solar Radiation Storm Forecast for Jun 28-Jun 30 2026

              Jun 28  Jun 29  Jun 30
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

No radio blackouts were observed over the past 24 hours.

Radio Blackout Forecast for Jun 28-Jun 30 2026

              Jun 28        Jun 29        Jun 30
R1-R2           50%           50%           50%
R3 or greater   10%           10%           10%

Rationale: A high chance for R1-2 (Minor-Moderate) radio blackouts due
to M-class flare activity will presist through 30 Jun primarily due to
the flare potential presently observed in Regions 4475 and 4478.


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