397
FXXX10 KWNP 271231
DAYTDF

:Product: 3-Day Forecast
:Issued: 2025 Aug 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 2 (below NOAA
Scale levels).
The greatest expected 3 hr Kp for Aug 27-Aug 29 2025 is 2.67 (below NOAA
Scale levels).

NOAA Kp index breakdown Aug 27-Aug 29 2025

             Aug 27       Aug 28       Aug 29
00-03UT       1.33         2.00         2.33
03-06UT       1.33         2.67         2.67
06-09UT       1.00         2.67         2.00
09-12UT       2.67         2.67         1.67
12-15UT       2.33         2.33         1.67
15-18UT       1.67         2.00         2.00
18-21UT       1.67         1.00         2.00
21-00UT       2.00         0.67         2.33

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
above S-scale storm level thresholds.

Solar Radiation Storm Forecast for Aug 27-Aug 29 2025

              Aug 27  Aug 28  Aug 29
S1 or greater   99%     35%     10%

Rationale: The greater than 10 MeV proton flux is expected to continue
at the S1 (Minor) solar radiation storm threshold of 10 pfu on
27 Aug. A gradual return to background levels is anticipated thereafter.

C. NOAA Radio Blackout Activity and Forecast

Radio blackouts reaching the R1 levels were observed over the past 24
hours. The largest was at Aug 26 2025 1407 UTC.

Radio Blackout Forecast for Aug 27-Aug 29 2025

              Aug 27        Aug 28        Aug 29
R1-R2           60%           60%           65%
R3 or greater   10%           10%           15%

Rationale: Solar activity is likely to reach moderate levels (R1-R2,
Minor-Moderate) through 29 Aug due to M-class flare activity with a
slight chance for an isolated X-class flare (R3-Strong) event.