 roduct: 3-Day Forecast
:Issued: 2026 Sep 09 0030 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 5 (NOAA Scale
G1).
The greatest expected 3 hr Kp for Sep 09-Sep 11 2026 is 5.67 (NOAA Scale
G2).
NOAA Kp index breakdown Sep 09-Sep 11 2026
Sep 09 Sep 10 Sep 11
00-03UT 5.00 (G1) 3.00 2.00
03-06UT 5.67 (G2) 2.67 2.33
06-09UT 4.00 2.67 2.00
09-12UT 3.33 2.33 2.00
12-15UT 2.67 1.33 2.33
15-18UT 3.00 2.00 2.67
18-21UT 3.00 2.00 2.67
21-00UT 3.33 2.33 3.00
Rationale: G1-G2 (Minor-Moderate) geomagnetic storms are likely on 09
Sep due to the combination of positive polarity coronal hole high speed
stream effects and the anticipated arrival of CMEs that left the Sun
05-06 Sep.
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 Sep 09-Sep 11 2026
Sep 09 Sep 10 Sep 11
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 Sep 09-Sep 11 2026
Sep 09 Sep 10 Sep 11
R1-R2 10% 10% 10%
R3 or greater 1% 1% 1%
Rationale: Solar activity is likely to be at low levels with
occasional C-class flare activity and a slight chance for M-class
flares (R1-R2/Minor-Moderate) through 11 Sep.
--- MBSE BBS v1.1.7.2 (Linux-x86_64)
* Origin: Outpost BBS * Johnson City, TN (618:618/1)
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