Routine Space Environment Product (Daily)
Issued by NWS
Issued by NWS
685
FXXX10 KWNP 171231
DAYTDF
:Product: 3-Day Forecast
:Issued: 2025 May 17 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 May 17-May 19 2025 is 6.33 (NOAA Scale
G2).
NOAA Kp index breakdown May 17-May 19 2025
May 17 May 18 May 19
00-03UT 6.33 (G2) 3.67 4.67 (G1)
03-06UT 5.33 (G1) 3.67 5.00 (G1)
06-09UT 3.33 4.00 4.67 (G1)
09-12UT 4.67 (G1) 4.67 (G1) 4.33
12-15UT 5.33 (G1) 3.67 3.67
15-18UT 5.67 (G2) 4.33 4.00
18-21UT 5.00 (G1) 4.67 (G1) 4.00
21-00UT 3.67 4.67 (G1) 3.67
Rationale: CME effects are expected to persist, keeping conditions at
active to G1-G2 (Minor-Moderate) levels on 17 May. An anticipated CIR is
likely to bring additional chances for G1 (Minor) storm levels on 18
May, with a chance for G2 (Moderate) levels on 19 May as the positive
polarity CH HSS settles in.
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 May 17-May 19 2025
May 17 May 18 May 19
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 May 17-May 19 2025
May 17 May 18 May 19
R1-R2 55% 55% 55%
R3 or greater 20% 15% 15%
Rationale: R1/R2 (Minor/Moderate) radio blackouts are likely with a
slight chance for an R3 (Strong) event on 17-19 May.