Daily Report

(last updated 20 May 2026 23:30 UT)

SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT ISSUED AT 2330UT/20 MAY 2026 FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE SUMMARY FOR 20 MAY AND FORECAST FOR 21 MAY - 23 MAY STATUS INDICATORS SOL:** YELLOW ** MAG:GREEN ION: GREEN ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx ----------------------------------------------------------- 1A. SOLAR SUMMARY Activity 20 May: R0 Flares: none. Observed 10.7 cm flux/Equivalent Sunspot Number for 20 May: 114/65 1B. SOLAR FORECAST 21 May 22 May 23 May Activity R0, chance of R1 R0, chance of R1 R0, chance of R1 Fadeouts Possible Possible Possible 10.7cm/SSN 110/60 108/58 115/66 COMMENT: Solar flare activity on UT day 20-May was at the R0 level, with no significant flaring activity. There are currently five numbered sunspot regions visible on the solar disk. AR4441 (N08W25, beta) showed some spot development over the UT day and is the largest and most magnetically complex region on the solar disk. All other sunspot regions are either stable or in decay. Solar flare activity is expected to be at the R0 level over 21-23 May, with a chance of R1. S0 solar radiation conditions were observed on UT day 20-May. S0 solar radiation conditions are expected over 21-23 May. No Earth-directed coronal mass ejections (CMEs) were observed on 20-May. The solar wind speed decreased over 21-May. The speed ranged from 435 to 540 km/s and is currently near 450 km/s. The peak total interplanetary magnetic field strength (IMF, Bt) was 7 nT and the north-south IMF component (Bz) range was -4 to +5 nT. The solar wind speed is expected to continue to decline towards background levels and remain there over 21-23 May. ----------------------------------------------------------- 2A. MAGNETIC SUMMARY Geomagnetic field for Australian Region 20 May: G0 Estimated Indices 20 May : A K Australian Region 2 22100001 Cocos Island 2 12110000 Darwin 4 22200112 Townsville 2 22100011 Learmonth 3 22200011 Alice Springs 2 22100001 Gingin 2 22100011 Canberra 1 21100000 Kennaook Cape Grim 2 22100000 Hobart 3 23100000 Estimated Antarctic Regional K Indices 20 May : Macquarie Island 3 23100000 Casey 6 33211111 Mawson 26 64422225 Observed Regional daily pc3 Indices 20 May : Darwin 0 (Quiet) Townsville 0 (Quiet) Learmonth 0 (Quiet) Alice Springs 0 (Quiet) Gingin 6 (Quiet) Canberra 23 (Quiet to unsettled) Hobart 53 (Unsettled) Pc3 pulsations are high frequency (10-45 second period) variations of the Earths magnetic field. Daily pc3-indices are the daily sum of 20 minute pc3-indices for that station and have been shown to be well correlated with rejection of high resolution aeromagnetic survey flight-line data. NOTE: Indices may have been generated from data obtained in cooperation with the following organisations: Geoscience Australia, University of Newcastle Space Physics Group, Australian Government Antarctic Division and International Center for Space Weather Science and Education, Japan. Estimated AFr/Ap Indices 20 May : A Fredericksburg 8 Planetary 8 Observed AFr/Ap Indices 19 May : A K Fredericksburg 18 Planetary 19 2344 4433 2B. MAGNETIC FORECAST Date Ap Conditions 21 May 7 G0 22 May 5 G0 23 May 4 G0 COMMENT: G0 geomagnetic conditions were observed in the Australian region on UT day 20-May. Mostly G0 geomagnetic conditions were observed in the Antarctic region, with G2 conditions observed at Mawson at the beginning of the UT day. G0 geomagnetic conditions are expected over 21-23 May. ----------------------------------------------------------- 3A. GLOBAL HF PROPAGATION SUMMARY Latitude Band Date Low Middle High 20 May Normal Normal-fair Normal-fair PCA Event : No event. 3B. GLOBAL HF PROPAGATION FORECAST Latitude Band Date Low Middle High 21 May Normal Normal Normal 22 May Normal Normal Normal 23 May Normal Normal Normal COMMENT: Global ionospheric conditions were normal to fair over UT day 20-May, with degradations mostly observed in the northern hemisphere. Mostly normal HF propagation conditions are expected over 21-23 May. ----------------------------------------------------------- 4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY Date T index 20 May 48 Observed Australian Regional MUFs Cocos Island Region: No data available during local day. No data available during local night. Niue Island Region: Depressed by 15% during local day. Depressed by 30% during local night. Northern Australian Region: Near predicted monthly values during local day. Depressed by 20% during local night. Southern Australian Region: Depressed by 15% during local day. Depressed by 20% during local night. Antarctic Region (Casey/Davis/Mawson): Depressed by 20% over the UT day. Monthly T index: Month T index Apr 74 May 71 Jun 68 4B. AUSTRALIAN REGION IONOSPHERIC FORECAST Date T index MUFs 21 May 55 Near predicted monthly values/depressed 5 to 15% 22 May 60 Near predicted monthly values/depressed 5 to 15% 23 May 60 Near predicted monthly values/depressed 5 to 15% COMMENT: Maximum Usable Frequencies (MUFs) on UT day were depressed by up to 20% during local night hours and by up to 15% during local day hours in the southern Australian region. Spread-F and sporadic E were observed at Hobart, with milder spread-f observed at Canberra and Perth during local night hours. MUFs are expected to be near predicted monthly values over 21-23 May, with a chance of mild depressions, particularly in the southern Australian region. ----------------------------------------------------------- 5. SPACE ENVIRONMENT SUMMARY GOES satellite data for 19 May Daily Proton Fluence >1 MeV: 2.0E+06 Daily Proton Fluence >10 MeV: 1.8E+04 Daily Electron Fluence >2 MeV: 1.20E+08 (moderate fluence) Electron Fluence Daily Deep Dielectric Discharge Probability:12% Fluence (flux accumulation over 24hrs)/ cm2-ster-day. X-ray background: B3.3 DSCOVR Satellite Solar Wind Day Averaged Data for 19 May Speed: 523 km/sec Density: 1.4 p/cc Temp: 123000 K Bz: -3 nT (Courtesy Space Weather Prediction Center, Boulder USA) -----------------------------------------------------------