049
FXXX10 KWNP 211231
DAYTDF

:Product: 3-Day Forecast
:Issued: 2026 Jul 21 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 Jul 21-Jul 23 2026 is 5.33 (NOAA Scale
G1).

NOAA Kp index breakdown Jul 21-Jul 23 2026

             Jul 21       Jul 22       Jul 23
00-03UT       2.33         3.67         4.00
03-06UT       2.67         5.00 (G1)    3.00
06-09UT       3.00         5.33 (G1)    2.67
09-12UT       3.67         4.00         2.00
12-15UT       4.33         3.67         2.00
15-18UT       2.67         3.33         2.67
18-21UT       2.33         3.00         3.00
21-00UT       3.00         4.33         3.00

Rationale: G1 (Minor) geomagnetic storms are likely on 22 Jul due to
negative polarity coronal hole high speed stream effects.

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 Jul 21-Jul 23 2026

              Jul 21  Jul 22  Jul 23
S1 or greater    5%      5%      5%

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

Radio blackouts reaching the R1 levels were observed over the past 24
hours. The largest was at Jul 20 2026 2225 UTC.

Radio Blackout Forecast for Jul 21-Jul 23 2026

              Jul 21        Jul 22        Jul 23
R1-R2           55%           55%           55%
R3 or greater    5%            5%            5%

Rationale: Solar activity is expected to be low with further M-class
flares (R1-R2, Minor-Moderate) likely on 21-23 Jul primarily due to the
flare potential of AR 4493.