Message 28367 in SPACWX.USA
From: N4SD
Date: Fri, 21 Aug 26 00:31:00 Z
Newsgroups: SPACWX.USA
Subject: Space Weather 3-Day Forecast
Message-ID: <21072_N4SD>
Path: K7EK|N2GWK|N5MDT|NS2B|N3IP|KA3VSP|N4SD
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FXXX10 KWNP 210031
DAYTDF
:Product: 3-Day Forecast
:Issued: 2026 Aug 21 0030 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 3 (below NOAA
Scale levels).
The greatest expected 3 hr Kp for Aug 21-Aug 23 2026 is 4.00 (below NOAA
Scale levels).
NOAA Kp index breakdown Aug 21-Aug 23 2026
Aug 21 Aug 22 Aug 23
00-03UT 3.00 2.67 3.00
03-06UT 3.67 4.00 2.00
06-09UT 2.67 2.33 2.00
09-12UT 2.33 2.33 2.00
12-15UT 2.33 2.00 2.00
15-18UT 1.67 1.00 2.00
18-21UT 2.33 2.00 2.00
21-00UT 2.67 2.00 2.33
Rationale: No G1 (Minor) or greater geomagnetic storms are expected. No
significant transient or recurrent solar wind features are forecast.
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 Aug 21-Aug 23 2026
Aug 21 Aug 22 Aug 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 R2 levels were observed over the past 24
hours. The largest was at Aug 20 2026 1142 UTC.
Radio Blackout Forecast for Aug 21-Aug 23 2026
Aug 21 Aug 22 Aug 23
R1-R2 40% 40% 40%
R3 or greater 10% 10% 10%
Rationale: There is a chance for R1-R2 (Minor-Moderate), and a slight
chance for R3 (Strong) or greater radio blackouts on 21-23 Aug.
------
73 de Sperry N4SD
N4SD@N4SD.#TIDE.VA.USA.NOAM
Received via NOAA GOES-East satellite downlink
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