Message:21054 In: SPACWX.USA
From: N4SDDate: Sat, 18 Apr 26 12:32:00 Z
Newsgroups: SPACWX.USA
Subject: Space Weather 3-Day Forecast
Message-ID: <11414_N4SD>
Path: N2MH4|N3MEL|KA3VSP|N4SD
R:260418/1856Z 30374@N2MH4.#SENC.NC.USA.NOAM LinBPQ6.0.24
R:260418/1856Z 15922@N3MEL.#EPA.PA.USA.NOAM LinBPQ6.0.25
R:260418/1851Z 934@KA3VSP.DE.USA.NOAM BPQ6.0.25
R:260418/1232Z 11414@N4SD.#TIDE.VA.USA.NOAM BPQ6.0.24
FXXX10 KWNP 181231
DAYTDF
:Product: 3-Day Forecast
:Issued: 2026 Apr 18 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 6 (NOAA Scale
G2).
The greatest expected 3 hr Kp for Apr 18-Apr 20 2026 is 6.00 (NOAA Scale
G2).
NOAA Kp index breakdown Apr 18-Apr 20 2026
Apr 18 Apr 19 Apr 20
00-03UT 3.33 5.00 (G1) 3.67
03-06UT 5.00 (G1) 4.67 (G1) 3.67
06-09UT 5.67 (G2) 4.00 3.33
09-12UT 5.00 (G1) 3.33 3.33
12-15UT 5.00 (G1) 3.67 3.33
15-18UT 4.33 3.00 2.00
18-21UT 4.00 3.00 3.33
21-00UT 6.00 (G2) 3.33 3.33
Rationale: G1-G2 (Minor-Moderate) geomagnetic storming levels are
expected on 18 Apr as negative polarity CH HSS geomagnetic conditions
persist. Active to G1 (Minor) levels are expected to continue through 19
Apr, followed by unsettled to active conditions on 20 Apr, as HSS
effects linger.
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 18-Apr 20 2026
Apr 18 Apr 19 Apr 20
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 18-Apr 20 2026
Apr 18 Apr 19 Apr 20
R1-R2 25% 25% 25%
R3 or greater 5% 5% 5%
Rationale: There is a chance for R1-R2 (Minor-Moderate) flares on 18-20
Apr, primarily due to the flare potential of Region 4419.
------
73 de Sperry N4SD
N4SD@N4SD.#TIDE.VA.USA.NOAM
Received via NOAA GOES-East satellite downlink
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