####018002082#### FXXX10 KWNP 151231 DAYTDF :Product: 3-Day Forecast :Issued: 2026 Mar 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 5 (NOAA Scale G1). The greatest expected 3 hr Kp for Mar 15-Mar 17 2026 is 4.67 (NOAA Scale G1). NOAA Kp index breakdown Mar 15-Mar 17 2026 Mar 15 Mar 16 Mar 17 00-03UT 4.00 3.67 2.67 03-06UT 2.00 3.67 3.00 06-09UT 2.33 3.00 2.33 09-12UT 3.67 2.33 2.33 12-15UT 4.67 (G1) 2.00 2.33 15-18UT 3.33 2.67 2.33 18-21UT 2.00 3.00 2.33 21-00UT 2.33 3.00 2.00 Rationale: G1 (Minor) geomagnetic storms are likely on 15 Mar due to influence from a positive polarity coronal hole. 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 Mar 15-Mar 17 2026 Mar 15 Mar 16 Mar 17 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 Mar 15-Mar 17 2026 Mar 15 Mar 16 Mar 17 R1-R2 15% 15% 15% R3 or greater 1% 1% 1% Rationale: There exists a slight chance for R1-R2 (Minor-Moderate) radio blackouts over 15-17 Mar. ####018002454#### FXXX12 KWNP 151231 DAYDIS :Product: Forecast Discussion :Issued: 2026 Mar 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 reached moderate levels. Region 4392 (S15E33, Cao/beta) produced the strongest flare of the period, an M1.0 flare at 15/0939 UTC. Only minor changes were observed among the spotted numbered regions on the visible disk. No Earth-directed CMEs were observed in available coronagraph imagery. .Forecast... Solar activity is expected to be at low levels, with a slight chance for M-class (R1-R2/Minor-Moderate) flares through 17 Mar. 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 normal to moderate levels through 15 Mar before reaching high levels on 16 and 17 Mar due to high speed stream effects. The greater than 10 MeV proton flux is expected to continue at background levels through 17 Mar. Solar Wind .24 hr Summary... Solar wind parameters reflected the continued influence of a positive polarity CH HSS. Total magnetic field strength was between 5-9 nT. The Bz component was mostly positive but briefly reached as far south as -7 nT early in the reporting period. Solar wind speeds were in gradual decline, with speeds decreasing from ~700 km/s to ~650 km/s over the past 24 hours. Phi angle was predominantly oriented in the positive solar sector. .Forecast... Solar wind parameters are expected to remain elevated, but gradually decline over the next three days (15-17 Mar). There is a small potential for additional enhancement on 15-16 Mar from the periphery of a CME that left the Sun on 13 Mar. Geospace .24 hr Summary... The geomagnetic field was at quiet to G1 (Minor) geomagnetic storm levels due to positive polarity CH HSS effects. .Forecast... The geomagnetic field is likely to continue reaching active levels, with potential to reach G1 (Minor) levels, over 15-16 Mar under the waning phase of the coronal holes HSS. Unsettled levels are likely over 17 Mar.