####018002087#### FXXX10 KWNP 111231 DAYTDF :Product: 3-Day Forecast :Issued: 2024 May 11 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 9 (NOAA Scale G5). The greatest expected 3 hr Kp for May 11-May 13 2024 is 9.00 (NOAA Scale G5). NOAA Kp index breakdown May 11-May 13 2024 May 11 May 12 May 13 00-03UT 9.00 (G5) 6.00 (G2) 3.00 03-06UT 8.33 (G4) 5.00 (G1) 7.00 (G3) 06-09UT 8.67 (G4) 6.00 (G2) 5.00 (G1) 09-12UT 9.00 (G5) 7.00 (G3) 4.00 12-15UT 7.33 (G3) 3.67 3.00 15-18UT 6.00 (G2) 5.00 (G1) 3.00 18-21UT 5.67 (G2) 4.00 4.00 21-00UT 7.00 (G3) 3.67 4.00 Rationale: G5 (Extreme) storm levels are expected on 11 May, followed by G3 (Strong) storm levels on 12-13 May-all due to CME impacts. B. NOAA Solar Radiation Activity Observation and Forecast Solar radiation, as observed by NOAA GOES-18 over the past 24 hours, was above S-scale storm level thresholds. Solar Radiation Storm Forecast for May 11-May 13 2024 May 11 May 12 May 13 S1 or greater 99% 99% 60% Rationale: S1 (Minor) or greater solar radiation storms are in progress and expected to continue through 13 May. C. NOAA Radio Blackout Activity and Forecast Radio blackouts reaching the R3 levels were observed over the past 24 hours. The largest was at May 11 2024 0123 UTC. Radio Blackout Forecast for May 11-May 13 2024 May 11 May 12 May 13 R1-R2 95% 95% 95% R3 or greater 75% 75% 75% Rationale: R3 (Strong) or greater radio blackouts are expected all three day. ####018003112#### FXXX12 KWNP 111231 DAYDIS :Product: Forecast Discussion :Issued: 2024 May 11 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 # # Forecast Discussion # Solar Activity .24 hr Summary... Solar activity was high. Region 3664 (S18W60, Fkc/beta-gamma-delta) produced the strongest event of the period, an X5.8/2b flare (R3/Strong) at 11/0123 UTC. Associated with the event was a Type II and Type IV radio sweep, a Castelli-U signature, and a 800 sfu Tenflare. A subsequent halo CME signature was identified in SOHO/LASCO C2 imagery beginning at 11/0136 UTC. The event is currently being analyzed and modeled. Another R3 event was ongoing at the time of this writing. The region produced numerous low-level M-class active throughout the entire past 24 hours. Two new regions were numbered in the SE quadrant near the limb. They were both relatively quiet and stable during the reporting period. .Forecast... Solar activity is expected to persist at high to very high levels over 11-13 May, with M-class (R1-R2/Minor-Moderate) and X-class flares (R3/Strong) expected, due primarily to the flare potential of Region 3664. Energetic Particle .24 hr Summary... The greater than 10 MeV proton flux reached S2 (Moderate) solar radiation storm levels on 10 and 11 May. The greater than 2 MeV electron flux was at normal to moderate levels throughout the day. .Forecast... The greater than 10 MeV proton flux is expected to persist at S1 (Minor) storm levels through 12 May. Additional proton enhancements are likely on 12-13 May due to the flare potential and location of Region 3664. The greater than 2 MeV electron flux is expected to be at normal to moderate levels over 11-13 May. Solar Wind .24 hr Summary... This period saw the arrival of an strong interplanetary shock beginning at around 10/1635 UTC. Following initial shock arrival, total field strength increased to a peak of 74 nT and Bz was sustained southward, by as much as -50 nT. Solar wind speeds reached a peak of around 800 km/s late in the reporting period. .Forecast... A strongly enhanced solar wind environment and CME influences are expected to continue on 11 May. Additional enhancements are likely on 12-13 May due to the anticipated arrival of multiple other halo CMEs that left the Sun over 09-11 May. Geospace .24 hr Summary... The geomagnetic field reached G5 (Extreme) geomagnetic storm periods over the 10/2100-11/0000 UTC, 11/0000-11/0300 UTC, and 09/0900-1200 UTC synoptic periods due to the passage of multiple CMEs in the past 24 hours. .Forecast... Periods of G3-G4 (Strong-Severe) geomagnetic storms are expected on 11 May due to continued CME activity. Periods of G3 (Strong) or greater are likely on 12 and 13 May due to the anticipated arrival of additional CMEs associated with eruptive activity from Region 3664 over 09-11 May.