####018002283#### FXXX10 KWNP 151231 DAYTDF :Product: 3-Day Forecast :Issued: 2024 May 15 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 3 (below NOAA Scale levels). The greatest expected 3 hr Kp for May 15-May 17 2024 is 4.67 (NOAA Scale G1). NOAA Kp index breakdown May 15-May 17 2024 May 15 May 16 May 17 00-03UT 1.67 2.33 2.33 03-06UT 2.00 2.00 1.33 06-09UT 2.67 2.67 1.67 09-12UT 2.33 2.33 1.67 12-15UT 2.33 2.00 2.33 15-18UT 2.00 2.67 2.33 18-21UT 2.67 3.00 3.33 21-00UT 4.67 (G1) 2.33 4.33 Rationale: G1 (Minor) geomagnetic storms are likely on 15 May as CME influence wanes. 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 15-May 17 2024 May 15 May 16 May 17 S1 or greater 99% 25% 15% Rationale: S1 (Minor) solar radiation storms are expected on 15 May 14 May with a chance on 16 May and a slight chance on 17 May due to the eruptive potential from now departed Region 3664. 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 14 2024 1651 UTC. Radio Blackout Forecast for May 15-May 17 2024 May 15 May 16 May 17 R1-R2 75% 40% 35% R3 or greater 40% 15% 10% Rationale: R1-R2 (Minor-Moderate) conditions are expected on 15 May due to the flare potential from now departed Region 3664. Probabilities drop to a chance on 16-17 May from the remaining active regions on the Suns visible disk. ####018003652#### FXXX12 KWNP 151231 DAYDIS :Product: Forecast Discussion :Issued: 2024 May 15 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 at very high levels. Region 3664 (S19, L=349) has exited the western limb. However, the region produced four X-class flares as it exited the visible disk. The first flare was an X1.7 flare at 14/0209 UTC. Associated with this event was a Castelli radio burst, a 447 sfu shock speed Type II sweep, a Type IV sweep and a 250 sfu Tenflare. The second was an impulsive X1.2 flare at 14/1255 UTC with a 1040 sfu shock speed Type II sweep. The third was an X8.7 flare at 14/1651 UTC. Associated with this event was a Castelli radio burst, a 279 sfu shock speed Type II sweep and a 1100 sfu Tenflare. This flare was the largest event of the current solar cycle. The fourth X-class flare was an X3.4 at 15/0837 UTC. Radio activity included a Type 4 sweep and 10.7 cm burst. The CME activity associated with the flares mentioned above is not expected to have an Earth-directed component. Region 3670 (N19W37, Dao/beta-gamma) exhibited slight growth while beginning to develop maturing penumbra. Region 3682 (N15E59, Dao/beta-gamma) was numbered this period and was the culprit for an M4.4/2n flare at 14/1738 UTC. Other notable activity included a filament eruption in the far northeastern quadrant which produced a CME that was first visible in SOHO coronagraph imagery at approximately 14/0948 UTC. Modeling of this event suggests that a glancing blow at Earth is possible by late 17 May. .Forecast... Solar activity is expected to be at high levels due to M-class flare activity (R1-2/Minor-Moderate Radio Blackouts) with a chance for X-class flares (R3 Strong). Energetic Particles .24 hr Summary... The greater than 10 MeV proton flux was at S1-2 (Minor-Moderate) solar radiation storm levels with a peak flux of 121 pfu at 14/0505 UTC. The 2 MeV electron flux was at moderate levels. .Forecast... The greater than 10 MeV proton flux is expected to remain at S1 (Minor) solar radiation storm levels over most of 15 May with a continued chance of S2 (Moderate) levels. Background levels are expected thereafter. The 2 MeV electron flux is expected to be at moderate to high levels all three dayd. Solar Wind .24 hr Summary... Solar wind parameters were slightly elevated. Total field was 4-7 nT and the Bz component was mostly -5 to 5 nT. Solar wind speeds remained elevated, around 550 km/s, due to possible positive polarity CH HSS and lingering CME effects. .Forecast... An enhanced solar wind environment with CME influences from a filament eruption from 12 May, another CME from 12 May, and a weak positive polarity CH HSS are anticipated for 15 May. A return to a quieter conditions is anticipated on 16 May. Another enhancement is possible by 17 May due to glancing influences from a CME that left the Sun on early 14 May. Geospace .24 hr Summary... The geomagnetic field was quiet to unsettled. .Forecast... G1 (Minor) geomagnetic storming is likely on 15 May due to positive polarity CH HSS and possible CME effects. Quiet to unsettled conditions are expected on 16 May as any weak CME effects wane. Unsettled to active conditions are expected by late 17 May with any glancing CME effects from the aforementioned 14 May event.