494
FXXX10 KWNP 200031
DAYTDF

:Product: 3-Day Forecast
:Issued: 2025 Apr 20 0030 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 20-Apr 22 2025 is 6.00 (NOAA Scale
G2).

NOAA Kp index breakdown Apr 20-Apr 22 2025

             Apr 20       Apr 21       Apr 22
00-03UT       2.67         2.00         3.00
03-06UT       4.00         1.00         2.00
06-09UT       2.33         1.00         3.00
09-12UT       1.67         1.00         4.00
12-15UT       1.33         1.00         4.33
15-18UT       1.00         2.00         5.00 (G1)
18-21UT       1.67         3.00         5.33 (G1)
21-00UT       2.00         3.67         6.00 (G2)

Rationale: Periods of G1-G2 (Minor-Moderate) geomagnetic storms are
likely on 22 Apr due to positive polarity CH HSS influences.

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 20-Apr 22 2025

              Apr 20  Apr 21  Apr 22
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

Radio blackouts reaching the R1 levels were observed over the past 24
hours. The largest was at Apr 19 2025 0030 UTC.

Radio Blackout Forecast for Apr 20-Apr 22 2025

              Apr 20        Apr 21        Apr 22
R1-R2           40%           40%           40%
R3 or greater    5%            5%            5%

Rationale: There is a chance for R1-R2 (Minor-Moderate) radio blackouts
over 20-22 Apr.