:Product: 3-Day Forecast
:Issued: 2021 Apr 21 1230 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 21-Apr 23 2021 is 3 (below NOAA
Scale levels).

NOAA Kp index breakdown Apr 21-Apr 23 2021

            Apr 21     Apr 22     Apr 23
00-03UT        2          2          2     
03-06UT        3          2          2     
06-09UT        2          2          2     
09-12UT        2          1          2     
12-15UT        2          1          2     
15-18UT        2          1          2     
18-21UT        1          1          2     
21-00UT        2          1          3     

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-16 over the past 24 hours, was
below S-scale storm level thresholds.

Solar Radiation Storm Forecast for Apr 21-Apr 23 2021

              Apr 21  Apr 22  Apr 23
S1 or greater    1%      1%      1%

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 Apr 21-Apr 23 2021

              Apr 21        Apr 22        Apr 23
R1-R2           15%           15%           15%
R3 or greater    1%            1%            1%

Rationale: There is slight chance for R1 (Minor) radio blackouts on Apr
21-23.