Subj : 3 Day Space Weather Forecast
To   : All
From : Sean Dennis
Date : Mon Oct 19 2026 12:19 am

:Product: 3-Day Forecast
:Issued: 2026 Oct 19 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 2 (below NOAA
Scale levels).
The greatest expected 3 hr Kp for Oct 19-Oct 21 2026 is 4.67 (NOAA Scale
G1).

NOAA Kp index breakdown Oct 19-Oct 21 2026

             Oct 19       Oct 20       Oct 21
00-03UT       2.33         4.33         3.33         
03-06UT       2.00         4.67 (G1)    3.67         
06-09UT       1.33         3.67         3.00         
09-12UT       2.67         3.00         2.67         
12-15UT       3.00         3.00         2.33         
15-18UT       3.67         3.00         2.00         
18-21UT       4.67 (G1)    3.33         3.33         
21-00UT       4.33         3.67         3.00         

Rationale: Periods of G1 (Minor) geomagnetic storming are likely on
19-20 Oct due to CH HSS 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 19-Oct 21 2026

              Oct 19  Oct 20  Oct 21
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

No radio blackouts were observed over the past 24 hours.

Radio Blackout Forecast for Oct 19-Oct 21 2026

              Oct 19        Oct 20        Oct 21
R1-R2           25%           25%           25%
R3 or greater    5%            5%            5%

Rationale: There is a chance for R1-R2 (Minor-Moderate) radio blackouts
on 19-21 Oct.


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