####018002151#### FXXX10 KWNP 201231 DAYTDF :Product: 3-Day Forecast :Issued: 2026 Apr 20 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 4 (below NOAA Scale levels). The greatest expected 3 hr Kp for Apr 20-Apr 22 2026 is 4.00 (below NOAA Scale levels). NOAA Kp index breakdown Apr 20-Apr 22 2026 Apr 20 Apr 21 Apr 22 00-03UT 0.67 3.33 2.67 03-06UT 2.33 4.00 2.00 06-09UT 4.00 3.00 2.33 09-12UT 3.67 2.67 2.00 12-15UT 3.67 2.33 2.00 15-18UT 3.00 3.00 2.33 18-21UT 3.00 2.67 2.00 21-00UT 2.67 2.33 2.00 Rationale: No G1 (Minor) or greater geomagnetic storms are expected. No significant transient or recurrent solar wind features are forecast. 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 Apr 20-Apr 22 2026 Apr 20 Apr 21 Apr 22 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 Apr 20-Apr 22 2026 Apr 20 Apr 21 Apr 22 R1-R2 5% 5% 10% R3 or greater 1% 1% 1% Rationale: No R1 (Minor) or greater radio blackouts are expected. No significant active region flare activity is forecast. ####018002954#### FXXX12 KWNP 201231 DAYDIS :Product: Forecast Discussion :Issued: 2026 Apr 20 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 low levels with an isolated C1.0/Sf flare from Region 4419 (N15W19, Eko/beta-gamma). This region exhibited minor growth in overall area, but had slight decay in the number of spots. Aside from the aforementioned C1 flare, Region 4419 contributed mostly B-level enhancements during the period. Region 4415 (S18W80, Hsx/alpha) remained unchanged and was inactive. At approximately 19/1449 UTC, a disappearing solar filament was noted in GONG H-alpha and GOES SUVI imagery near N07E31. Subsequent analysis indicated a trajectory well behind Earths orbit with no impacts expected. No Earth directed CMEs were observed in coronagraph imagery. .Forecast... Solar activity is expected to be at very low levels, with a chance for isolated C-class activity on 20-22 Apr, primarily due to the flare potential from Region 4419 and limb activity. Energetic Particle .24 hr Summary... The greater than 2 MeV electron flux at geosynchronous orbit reached high levels at 19/1925 UTC with a maximum reading of 1,187 pfu. The greater than 10 MeV proton flux was at background levels. .Forecast... The greater than 2 MeV electron flux is expected to be at moderate to high levels on 20-22 Apr. The greater than 10 MeV proton flux is expected to continue at background levels on 20-22 Apr. Solar Wind .24 hr Summary... Solar wind parameters continued to reflect negative polarity CH HSS influence throughout most of the period. Total field ranged from 2-7 nT, the Bz component fluctuated between +/-5 nT, and solar wind speeds gradually decreased from 550 km/s to 400 km/s. At approximately 20/0600 UTC, a weak enhancement was observed in the solar wind environment. Total field increased slightly to 8 nT, the Bz component simultaneously saw a southward deflection to -8 nT, and wind speeds increased back to near 500 km/s. Phi was mostly in a negative orientation, with isolated oscillations into a positive position. .Forecast... Weakening enhanced solar wind conditions are expected on 20-21 Apr as the CH HSS continues to move from its geoeffective position. A return to mostly nominal conditions is expected by 22 Apr. Geospace .24 hr Summary... The geomagnetic field was at quiet to active levels as CH HSS influence persists. .Forecast... Mostly quiet to unsettled levels, with isolated active conditions, are expected on 20-21 Apr as HSS effects diminish. Mostly quiet levels are expected, with possible unsettled periods on 22 Apr as CH HSS influence dissipates.