407
FXXX10 KWNP 271231
DAYTDF

:Product: 3-Day Forecast
:Issued: 2026 Apr 27 1230 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 3 (below NOAA
Scale levels).
The greatest expected 3 hr Kp for Apr 27-Apr 29 2026 is 3.33 (below NOAA
Scale levels).

NOAA Kp index breakdown Apr 27-Apr 29 2026

             Apr 27       Apr 28       Apr 29
00-03UT       3.00         1.67         2.00
03-06UT       2.00         1.33         2.33
06-09UT       1.00         1.33         1.67
09-12UT       1.33         1.33         1.33
12-15UT       2.00         1.67         1.00
15-18UT       1.33         1.33         2.67
18-21UT       2.33         1.33         3.00
21-00UT       2.33         1.67         3.33

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 Apr 27-Apr 29 2026

              Apr 27  Apr 28  Apr 29
S1 or greater   10%     10%     10%

Rationale: There is a slight chance the greater than 10 MeV proton flux
could reach S1 (Minor) levels, but is mainly expected to remain at
background levels 27-29 Apr.

C. NOAA Radio Blackout Activity and Forecast

Radio blackouts reaching the R2 levels were observed over the past 24
hours. The largest was at Apr 26 2026 2257 UTC.

Radio Blackout Forecast for Apr 27-Apr 29 2026

              Apr 27        Apr 28        Apr 29
R1-R2           70%           70%           70%
R3 or greater   25%           25%           25%

Rationale: There is a high likelihood for R1/R2 (Minor/Moderate) radio
blackouts, and a slight chance for R3 (Strong or greater) events through
29 Apr, due primarily to the complexity of regions 4420 and 4425.