:Product: 3-Day Forecast
:Issued: 2026 Mar 11 0040 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 4 (below NOAA
Scale levels).
The greatest expected 3 hr Kp for Mar 11-Mar 13 2026 is 5.00 (NOAA Scale
G1).

NOAA Kp index breakdown Mar 11-Mar 13 2026

             Mar 11       Mar 12       Mar 13
00-03UT       2.67         1.67         1.67     
03-06UT       2.33         1.33         1.33     
06-09UT       2.00         1.33         1.33     
09-12UT       2.00         1.33         2.67     
12-15UT       1.00         1.33         3.33     
15-18UT       1.33         1.67         5.00 (G1)
18-21UT       1.00         1.33         4.33     
21-00UT       1.67         1.67         4.33     

Rationale: Isolated periods of G1 (Minor) storming are possible on 13
Mar because of the onset of a positive polarity coronal hole high speed
stream (+CH HSS).

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 Mar 11-Mar 13 2026

              Mar 11  Mar 12  Mar 13
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 Mar 11-Mar 13 2026

              Mar 11        Mar 12        Mar 13
R1-R2           20%           20%           20%
R3 or greater    1%            1%            1%

Rationale: There exists a slight chance for R1-R2 (Minor-Moderate) radio
blackouts over 11-13 Mar.