Message:21186 In: SPACWX.USA
From: N4SDDate: Tue, 21 Apr 26 00:32:00 Z
Newsgroups: SPACWX.USA
Subject: Space Weather 3-Day Forecast
Message-ID: <11600_N4SD>
Path: N2MH4|N3MEL|KA3VSP|N4SD
R:260421/0252Z 30451@N2MH4.#SENC.NC.USA.NOAM LinBPQ6.0.24
R:260421/0251Z 16048@N3MEL.#EPA.PA.USA.NOAM LinBPQ6.0.25
R:260421/0235Z 1037@KA3VSP.DE.USA.NOAM BPQ6.0.25
R:260421/0032Z 11600@N4SD.#TIDE.VA.USA.NOAM BPQ6.0.24
FXXX10 KWNP 210031
DAYTDF
:Product: 3-Day Forecast
:Issued: 2026 Apr 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 5 (NOAA Scale
G1).
The greatest expected 3 hr Kp for Apr 21-Apr 23 2026 is 4.00 (below NOAA
Scale levels).
NOAA Kp index breakdown Apr 21-Apr 23 2026
Apr 21 Apr 22 Apr 23
00-03UT 3.33 2.67 1.67
03-06UT 4.00 2.00 1.33
06-09UT 3.00 2.33 1.33
09-12UT 2.67 2.00 1.33
12-15UT 2.33 2.00 1.33
15-18UT 3.00 2.33 1.33
18-21UT 2.67 2.00 1.67
21-00UT 2.33 2.00 1.67
Rationale: Active periods (below NOAA G-scale levels) of geomagnetic
activity are expected on 21 Apr, with a slight chance for a G1 (Minor)
geomagnetic storm as the CH HSS effects wane. No geomagnetic storms are
expected on 22-23 Apr.
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 Apr 21-Apr 23 2026
Apr 21 Apr 22 Apr 23
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 Apr 21-Apr 23 2026
Apr 21 Apr 22 Apr 23
R1-R2 5% 5% 5%
R3 or greater 1% 1% 1%
Rationale: No R1 (Minor) or greater radio blackouts are expected. No
significant active region flare activity is forecast.
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73 de Sperry N4SD
N4SD@N4SD.#TIDE.VA.USA.NOAM
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