Message:21218 In: SPACWX.USA
From: N4SDDate: Tue, 21 Apr 26 12:32:00 Z
Newsgroups: SPACWX.USA
Subject: Space Weather 3-Day Forecast
Message-ID: <11655_N4SD>
Path: N2MH4|N3MEL|N3FUD|KA3VSP|N4SD
R:260421/1549Z 30468@N2MH4.#SENC.NC.USA.NOAM LinBPQ6.0.24
R:260421/1549Z 16076@N3MEL.#EPA.PA.USA.NOAM LinBPQ6.0.25
R:260421/1547Z 6631@N3FUD.#EPA.PA.USA.NOAM LinBPQ6.0.25
R:260421/1545Z 1068@KA3VSP.DE.USA.NOAM BPQ6.0.25
R:260421/1232Z 11655@N4SD.#TIDE.VA.USA.NOAM BPQ6.0.24
FXXX10 KWNP 211231
DAYTDF
:Product: 3-Day Forecast
:Issued: 2026 Apr 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 5 (NOAA Scale
G1).
The greatest expected 3 hr Kp for Apr 21-Apr 23 2026 is 4.67 (NOAA Scale
G1).
NOAA Kp index breakdown Apr 21-Apr 23 2026
Apr 21 Apr 22 Apr 23
00-03UT 4.67 (G1) 2.67 1.67
03-06UT 4.33 2.00 1.33
06-09UT 2.33 2.33 1.33
09-12UT 2.67 2.00 1.33
12-15UT 4.67 (G1) 2.00 1.33
15-18UT 3.67 2.33 1.33
18-21UT 2.67 2.00 1.67
21-00UT 2.33 2.00 1.67
Rationale: G1 (Minor) geomagnetic storms are possible on 21 Apr due to
lingering 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 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.
------
73 de Sperry N4SD
N4SD@N4SD.#TIDE.VA.USA.NOAM
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