448
FXXX10 KWNP 071231
DAYTDF

:Product: 3-Day Forecast
:Issued: 2026 Sep 07 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 4 (below NOAA
Scale levels).
The greatest expected 3 hr Kp for Sep 07-Sep 09 2026 is 5.00 (NOAA Scale
G1).

NOAA Kp index breakdown Sep 07-Sep 09 2026

             Sep 07       Sep 08       Sep 09
00-03UT       1.33         4.33         3.67
03-06UT       2.00         4.33         4.67 (G1)
06-09UT       3.33         4.67 (G1)    5.00 (G1)
09-12UT       4.00         4.67 (G1)    3.67
12-15UT       3.33         4.67 (G1)    3.33
15-18UT       3.67         4.00         3.33
18-21UT       3.67         4.33         3.00
21-00UT       3.33         3.33         2.67

Rationale: Isolated G1 (Minor) periods are likely and a slight chance of
reaching G2 (Moderate) levels on 08-09 Sep if the CMEs from 05-06 Sep
impact Earth as forecast. Confidence is low on the timing and magnitude
of the CME arrivals.

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 07-Sep 09 2026

              Sep 07  Sep 08  Sep 09
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 07-Sep 09 2026

              Sep 07        Sep 08        Sep 09
R1-R2           15%           15%           15%
R3 or greater    1%            1%            1%

Rationale: There is a slight chance for R1-R2 (Minor-Moderate) radio
blackouts through 09 Sep.