####018003107#### FXXX12 KWNP 131231 DAYDIS :Product: Forecast Discussion :Issued: 2026 May 13 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 remained at low levels, with minor C-class flares from Regions 4432 (N14W90, Eko/beta-gamma) - that is rotating off the West limb, 4433 (S16W60, Hrx/alpha) and 4436 (N18E20, Dai/beta). Region 4436 was responsible for the largest flare of the period: a C2.3 peaked at 13/0640 UTC. Two new regions were numbered during the past 24 hours: Region 4437 (N15W75, Axx/alpha) and 4438 (N19W23, Bxo/beta), resulting in a total of 5 numbered regions on the visible disk. No Earth-directed CMEs were observed in available coronagraph imagery. .Forecast... Solar activity is expected to remain predominately at low levels with a chance for M-class (R1-R2/Minor-Moderate) flares through 15 May. A slight chance for X-class (R3/Strong) flares still exists through the end of the 13 May UTC-day due to West-limb presence of Region 4432. Energetic Particle .24 hr Summary... The greater than 2 MeV electron flux was at normal to moderate levels. The greater than 10 MeV proton flux was at background levels. .Forecast... The greater than 2 MeV electron flux is expected to remain at moderate levels through 15 May. There is a slight chance for a S1 proton event until the end of the 13 May UTC-day, and no proton events above the S1 threshold are expected on 14-15 May. Solar Wind .24 hr Summary... The solar wind parameters near Earth suggested the anticipated glancing influence of the 10 May CME event: the total magnetic field strength slowly increased from about 5 to 8 nT during the day, jumping quickly towards 15 nT after 13/1100 UTC. The speeds and densities also showed enhancements during the period, with maximum speeds of 425 km/s after 13/1100 UTC. The north-south Bz component oscillated between -6/6 nT most of the day, reaching as north as 13 nT at the end of the period. Phi angle was predominantly positive until about 13/1100 UTC, when became negative. .Forecast... Solar wind parameters are expected to continue slightly disturbed through 14 May, as the glancing influence from the 10 May CME wanes and a positive polarity CH HSS remains geoeffective. On 15 May, a CIR associated with a negative polarity CH HSS is anticipated to arrive near Earth, likely resulting in more disturbed solar wind condition. Geospace .24 hr Summary... The geomagnetic field was quiet during the period. .Forecast... The geomagnetic field is expected to reach active conditions on 13-14 May, due to the glancing influences of the 10 May CME event and/or effects of a positive polarity CH HSS. A G2 (Moderate) storming conditions are likely on 15 May due to the anticipated arrival of a negative polarity CH HSS near Earth. ####018001999#### FXXX10 KWNP 131231 DAYTDF :Product: 3-Day Forecast :Issued: 2026 May 13 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 2 (below NOAA Scale levels). The greatest expected 3 hr Kp for May 13-May 15 2026 is 5.67 (NOAA Scale G2). NOAA Kp index breakdown May 13-May 15 2026 May 13 May 14 May 15 00-03UT 1.00 3.33 4.00 03-06UT 1.67 3.00 5.67 (G2) 06-09UT 1.67 2.33 4.00 09-12UT 1.67 2.00 3.67 12-15UT 3.00 1.67 3.67 15-18UT 2.00 2.00 3.67 18-21UT 3.67 2.67 4.00 21-00UT 3.33 3.67 3.67 Rationale: G2 (Moderate) geomagnetic storms are likely for 15 May due to the negative polatiry CH HSS CIR. B. NOAA Solar Radiation Activity Observation and Forecast Solar radiation, as observed by NOAA GOES-19 over the past 24 hours, was below S-scale storm level thresholds. Solar Radiation Storm Forecast for May 13-May 15 2026 May 13 May 14 May 15 S1 or greater 10% 5% 5% Rationale: There is a slight chance for S1 (Minor) or greater solar radiation storms on 13 May. C. NOAA Radio Blackout Activity and Forecast No radio blackouts were observed over the past 24 hours. Radio Blackout Forecast for May 13-May 15 2026 May 13 May 14 May 15 R1-R2 40% 40% 40% R3 or greater 10% 5% 5% Rationale: There is a chance for R1-R2 (Minor-Moderate) radio blackouts through 15 May.