:Product: Forecast Discussion :Issued: 2026 Jun 02 0030 UTC # Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center # Solar Activity .24 hr Summary... Solar activity remained at low levels, with isolated low-level C-class flaring observed. The strongest event of the period was a C1.5/Sf flare at 01/1724 UTC from Region 4449 (S09W43, Cro/beta). There are ten numbered regions on the visible disk. Region 4446 (S14W43, Cso/beta) showed minor growth and slight magnetic shear within its trailing spots. Region 4449 had rapid fragmentation of its leading spot group, and new flux emergence made the region magnetically bipolar. Region 4455 (N15E11, Cko/beta) continued to display fragmentation of its leading spot with transitory changes along its periphery. Region 4457 (S09W27, Bxo/beta) showed significant consolidation within both polarities, increasing its overall longitudinal length. Two new regions were numbered this period: Region 4458 (S04E20, Cro/beta) emerged rapidly on the disk and Region 4459 (N14E63, Bxo/beta) was numbered after emerging near the east limb. All other regions were stable. No Earth-directed CMEs were observed in available coronagraph imagery. .Forecast... Solar activity is expected to remain at low levels through 04 June, with a chance for isolated M-class flares (R1-R2/Minor-Moderate). Flaring potential is balanced over the next three days; while activity may decrease as several active regions rotate over the western limb, this is potentially offset by the complexity of Region 4455, the rapid development of interest in Region 4458, and active regions soon to rotate into view over the east limb indicated by bright loops and recent far-sided eruptions. Energetic Particle .24 hr Summary... The greater than 2 MeV electron flux at geosynchronous orbit was at low to moderate levels, with a peak flux of 551 pfu observed at 01/1620 UTC. The greater than 10 MeV proton flux remained at baseline background levels. .Forecast... The greater than 2 MeV electron flux is expected to remain at low to moderate levels through 04 June. The greater than 10 MeV proton flux is anticipated to remain at background levels through 04 June. Solar Wind .24 hr Summary... Solar wind parameters initially reflected nominal background conditions with total magnetic field (Bt) steady around 4 nT and solar wind speeds decreasing from 450 to 400 km/s. Around 01/1230 UTC, a minor enhancement occurred with Bt increasing to a peak of 7 nT. The North-South (Bz) component was southward the entire period, and reached a maximum deflection of -6 nT shortly after the transient onset. Solar wind speeds showing a minor speed bump following the start of the enhancement before slowly dropping back down to about 400 km/s. The phi angle remained predominantly in the negative (towards the Sun) sector. .Forecast... Solar wind parameters are anticipated to continue their decline back toward nominal background conditions through 02 June. Enhancements are possible early to midday on 03 June due to glancing influences from a slow-moving CME that departed the Sun on 30 May, though confidence remains low. Later on 03 June or early on 04 June, more significant enhancements are expected with the arrival of a co-rotating interaction region (CIR) ahead of a positive polarity coronal hole high-speed stream (+CH HSS). Geospace .24 hr Summary... The geomagnetic field was mostly quiet early in the period, but transitioned to unsettled levels later following the arrival of the slow-moving transient. .Forecast... Mostly quiet conditions with isolated unsettled periods are anticipated for 02 June as transient and weak negative polarity high-speed stream influences clear. Active conditions, with a chance for isolated periods of G1 (Minor) geomagnetic storming, are expected over 03–04 June due to the combined geoeffective arrivals of the low-confidence 30 May CME, the preceding CIR, and the subsequent +CH HSS.