421
FXXX10 KWNP 091231
DAYTDF

:Product: 3-Day Forecast
:Issued: 2026 Oct 09 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 Oct 09-Oct 11 2026 is 6.00 (NOAA Scale
G2).

NOAA Kp index breakdown Oct 09-Oct 11 2026

             Oct 09       Oct 10       Oct 11
00-03UT       3.33         4.00         4.67 (G1)
03-06UT       2.67         3.67         5.67 (G2)
06-09UT       3.00         3.00         4.33
09-12UT       3.67         3.00         3.00
12-15UT       4.67 (G1)    1.67         2.67
15-18UT       5.00 (G1)    2.33         2.33
18-21UT       6.00 (G2)    2.67         2.00
21-00UT       5.67 (G2)    2.67         2.67

Rationale: G1-G2 (Minor-Moderate) geomagnetic storming conditions are
expected late on 09 Oct and early on 11 Oct due to the anticipated
arrivals of several different CMEs with some potential negative polarity
coronal hole high speed stream 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 Oct 09-Oct 11 2026

              Oct 09  Oct 10  Oct 11
S1 or greater   10%     10%     10%

Rationale: There is a slight chance for S1 (Minor) or greater solar
radiation storms through 11 Oct, largely due to the flaring potential of
Region 4549.

C. NOAA Radio Blackout Activity and Forecast

Radio blackouts reaching the R2 levels were observed over the past 24
hours. The largest was at 08/1548Z UTC.

Radio Blackout Forecast for Oct 09-Oct 11 2026

              Oct 09        Oct 10        Oct 11
R1-R2           55%           55%           55%
R3 or greater   10%           10%           10%

Rationale: R1-R2 (Minor-Moderate) radio blackouts are likely, with a
slight chance for R3 (Strong) or greater events, through 11 Oct, largely
due to the flaring potential of Region 4549.