Solar Activity Alerts

:Product: Forecast Discussion :Issued: 2026 Sep 15 0030 UTC # Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center # Solar Activity .24 hr Summary... Solar activity was at very low levels during the period with only B-class flares observed. There are currently four numbered regions on the visible disk with none exhibiting magnetic complexity. A CME that was most likely associated with dimming near Region 4528 (S11W44, Hsx/alpha) was observed off the W Limb. Modeling results indicated a possible glancing arrival on 17 Sep. .Forecast... Solar activity is expected to be at very low levels, with a chance for isolated C-class flares and a slight chance for M-class flares through 17 Sep. Energetic Particle .24 hr Summary... The greater than 2 MeV electron flux reached high levels with a maximum flux of 1,827 pfu observed at 13/1800 UTC. The greater than 10 MeV proton flux was at background levels until approximately 14/0430 UTC when it began to rise, eventually reaching a peak of 4 pfu near 14/1500 UTC. .Forecast... The greater than 2 MeV electron flux is expected to reach high levels on 15 Sep before returning to moderate levels on 16-17 Sep. The greater than 10 MeV proton flux is expected to see a slow decline to background levels through 17 Sep. However, a slight chance (20%) for a rise above the 10 pfu threshold is possible due to its elevated state. Solar Wind .24 hr Summary... Solar wind parameters were enhanced and are possibly a reflection of the filament that departed the Sun on 09 Sep combined with the anticipated SSBC. Total field strength slowly increased to a peak of 14 nT after 14/1800 UTC. The Bz component was variable and briefly deflected southward to a maximum of -8 nT near 14/1435 UTC. Solar wind speeds remained below 400 km/s. The phi angle was variable throughout the period. .Forecast... Negative polarity CH HSS effects are anticipated to continue through 17 Sep. CMEs from the 13 and 14 Sep are likely to have flanking influences on 16 and 17 Sep. Geospace .24 hr Summary... The geomagnetic field reached active levels during a period of southward Bz. .Forecast... The geomagnetic field likely to reach active to G1 (Minor) storm levels on 15 and 16 Sep, with a chance for G1 conditions on 17 Sep. All due to combined CH and CME influences.

Space Weather Message Code: ALTK04 Serial Number: 2683 Issue Time: 2026 Sep 14 1802 UTC ALERT: Geomagnetic K-index of 4 Threshold Reached: 2026 Sep 14 1743 UTC Synoptic Period: 1500-1800 Active Warning: YES Comment: NOAA Space Weather Scale descriptions can be found at www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude. Induced Currents - Weak power grid fluctuations can occur. Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

Space Weather Message Code: WARK04 Serial Number: 5416 Issue Time: 2026 Sep 14 1654 UTC WARNING: Geomagnetic K-index of 4 expected Valid From: 2026 Sep 14 1653 UTC Valid To: 2026 Sep 14 2349 UTC Warning Conditions: Onset Comment: NOAA Space Weather Scale descriptions can be found at www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude. Induced Currents - Weak power grid fluctuations can occur. Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

Space Weather Message Code: WATA20 Serial Number: 1124 Issue Time: 2026 Sep 14 1547 UTC WATCH: Geomagnetic Storm Category G1 Predicted Highest Storm Level Predicted by Day: Sep 15: G1 (Minor) Sep 16: G1 (Minor) Sep 17: None (Below G1) THIS SUPERSEDES ANY/ALL PRIOR WATCHES IN EFFECT Comment: NOAA Space Weather Scale descriptions can be found at www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude. Induced Currents - Weak power grid fluctuations can occur. Spacecraft - Minor impact on satellite operations possible. Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

:Product: Forecast Discussion :Issued: 2026 Sep 14 1230 UTC # Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center # Solar Activity .24 hr Summary... Solar activity briefly reached low levels during the period. From 13/1841-1951 UTC, an 8 degree-long, N-S oriented filament, centered near S04W08, lifted off the disk. The eruption occurred to the west of Region 4528 (S11W38, Hsx/alpha), and was associated with a long-duration C1.4 flare, the only C-class flare of the period, at 13/1945 UTC. An associated CME first became visible in LASCO C2 at approximately 13/1948 UTC and in CCOR2 at approximately 13/2030 UTC. Modeling suggests the potential for a minor glancing blow early on 17 Sep. Occasional B-class flares were observed from Regions 4521 (N09, L=266), 4529 (N12W39, Cao/beta) and 4530 (N19W70, Cao/beta). The largest of these flares was a B9.2 at 13/1801 UTC from Region 4529. All four of the numbered regions experienced decay throughout the period. .Forecast... Solar activity is expected to be at very low levels, with a chance for isolated C-class flares through 16 Sep. Energetic Particle .24 hr Summary... The greater than 2 MeV electron flux reached high levels with a maximum flux of 1,827 pfu observed at 13/1800 UTC. The greater than 10 MeV proton flux was at background levels until approximately 14/0430 UTC when it began to rise, eventually reaching a peak near 3.5 pfu at 14/1025 UTC. The slight bump is likely associated with the long-duration C1.4 flare at 13/1945 UTC. .Forecast... The greater than 2 MeV electron flux is expected to reach high levels on 14 Sep and decline to low to moderate levels on 15 Sep before returning to high levels on 16 Sep. The greater than 10 MeV proton flux is expected to see the current enhancement weaken throughout the remainder of 14 Sep, returning to near background levels on 15-16 Sep. Solar Wind .24 hr Summary... Solar wind parameters remained near-background levels, with isolated weak perturbations noted around 14/0230 UTC and 14/1015 UTC. These minor disturbances are possibly a reflection of the filament that departed the Sun on 09 Sep combined with the anticipated SSBC. As expected, little magnetic reaction resulted from these events. Total field strength generally varied between 2-8 nT, eventually seeing a peak over 11 nT, and the Bz component saw isolated deviations as far south as -7 nT. Solar wind speed averaged around 425 km/s the first half of the period before decreasing to as low as 290 km/s the second half of the period. The phi angle was on the cusp of a positive/negative orientation for most of the period, spending several hours in each sector. .Forecast... Negative polarity CH HSS effects are anticipated to continue early on 14 Sep and last through 16 Sep. Geospace .24 hr Summary... The geomagnetic field was at quiet levels. .Forecast... The geomagnetic field is expected to be quiet to unsettled, with an isolated active period possible for the remainder of 14 Sep as -CH HSS influence builds in. Unsettled to active levels are then expected, with a chance for an isolated period of G1 (Minor) storming by 15 Sep. The likelihood of G1 storming increases on 16 Sep as a subsequent -CH HSS moves into a geoeffective position.