Daily Report

(last updated 19 Apr 2026 23:30 UT)

SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT ISSUED AT 2330UT/19 APRIL 2026 FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE SUMMARY FOR 19 APRIL AND FORECAST FOR 20 APRIL - 22 APRIL STATUS INDICATORS SOL:GREEN MAG:** YELLOW ** ION: GREEN ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx ----------------------------------------------------------- 1A. SOLAR SUMMARY Activity 19 Apr: R0 Flares: none. Observed 10.7 cm flux/Equivalent Sunspot Number for 19 Apr: 105/54 1B. SOLAR FORECAST 20 Apr 21 Apr 22 Apr Activity R0 R0 R0 Fadeouts None expected None expected None expected 10.7cm/SSN 105/54 110/60 120/72 COMMENT: Solar flare activity on UT day 19-Apr was at the R0 level, with no C-class or greater flares observed over the past 24 hours. There are currently two Active Regions (ARs) on the visible solar disk, with AR 4419 (N15W11, beta) being the largest and most magnetically complex. Both this region and AR 4415 (S18W76, alpha) have remained stable throughout UT day 19-Apr. Solar flare activity is forecast to remain at the R0 level over 20-22 Apr. S0 solar proton conditions were observed throughout the past UT day, with solar proton flux remaining at background levels. S0 solar proton conditions are expected over 20-22 Apr. No coronal mass ejections were observed in the past 24 hours in available coronagraph imagery. The solar wind speed was elevated on 19-Apr due to a coronal hole high speed wind stream. The solar wind speed was broadly constant, broadly ranging between 450 and 520 km/s across the UT day. The interplanetary magnetic field strength (IMF, Bt) peaked early in the UT day, reaching 12 nT, before declining over the course of the UT day. The north-south component (Bz) ranged between -7 and +9 nT over this time. An extended period of southward Bz was observed between 19/0410-0550UT. The solar wind speed is expected to slowly decline over 20-22 Apr, as the coronal hole high speed wind stream moves past its geoeffective position. ----------------------------------------------------------- 2A. MAGNETIC SUMMARY Geomagnetic field for Australian Region 19 Apr: G2 Estimated Indices 19 Apr : A K Australian Region 12 33432320 Cocos Island 6 22312210 Darwin 12 33432221 Townsville 12 33432221 Learmonth 13 33432321 Alice Springs 11 33432220 Gingin 12 32343320 Canberra 15 33532320 Kennaook Cape Grim 18 24543320 Hobart 15 34442320 Estimated Antarctic Regional K Indices 19 Apr : Macquarie Island 28 34564330 Casey 14 43332411 Mawson 60 55743656 Observed Regional daily pc3 Indices 19 Apr : Darwin 0 (Quiet) Townsville 0 (Quiet) Learmonth 0 (Quiet) Alice Springs 0 (Quiet) Gingin 21 (Quiet to unsettled) Canberra 38 (Quiet to unsettled) Hobart 24 (Quiet to 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 19 Apr : A Fredericksburg 18 Planetary 26 Observed AFr/Ap Indices 18 Apr : A K Fredericksburg 24 Planetary 33 ---- ---- 2B. MAGNETIC FORECAST Date Ap Conditions 20 Apr 20 G0, chance of G1 21 Apr 15 G0 22 Apr 12 G0 COMMENT: Geomagnetic conditions in the Australian region were at the G0 level throughout 19-Apr. A G1 interval was observed at Cape Grim. G2 geomagnetic conditions were reported at the planetary level, with an isolated G3 interval reported in the Antarctic region at Mawson. These geomagnetic conditions are due to an ongoing coronal hole high speed wind stream. The effects of this wind stream are expected to wane, with G0 geomagnetic conditions, with a chance of G1, are forecast for 20-Apr. This will decline further to G0 conditions over 21-22 Apr as this high speed wind stream moves past a geoeffective position. ----------------------------------------------------------- 3A. GLOBAL HF PROPAGATION SUMMARY Latitude Band Date Low Middle High 19 Apr Poor Poor Poor PCA Event : No event. 3B. GLOBAL HF PROPAGATION FORECAST Latitude Band Date Low Middle High 20 Apr Fair-poor Fair-poor Fair-poor 21 Apr Normal-fair Normal-fair Fair 22 Apr Normal Normal Normal-fair COMMENT: Global ionospheric conditions on UT day 19-Apr were poor, with widespread degradations observed at all latitudes due to ongoing geomagnetic activity. Conditions are expected to slowly recover over 20-22 Apr, with fair conditions on 20-Apr improving towards normal-fair conditions on 21-Apr, and normal conditions by 22-Apr. ----------------------------------------------------------- 4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY Date T index 19 Apr 71 Observed Australian Regional MUFs Cocos Island Region: Near predicted monthly values during local day. Depressed by 35% during local night. Niue Island Region: Mostly near predicted monthly values. Depressed by 25% after local dawn. Northern Australian Region: Near predicted monthly values during local day. Depressed by 35% during local night. Southern Australian Region: Near predicted monthly values during local day. Depressed by 15% during local night. Depressed by 20% after local dawn. Antarctic Region (Casey/Davis/Mawson): Depressed by 25% over the UT day. Monthly T index: Month T index Mar 92 Apr 83 May 81 4B. AUSTRALIAN REGION IONOSPHERIC FORECAST Date T index MUFs 20 Apr 65 Depressed 15 to 20%/near predicted monthly values 21 Apr 75 Near predicted monthly values 22 Apr 80 Near predicted monthly values COMMENT: ASWFC HF Communications Warning 37 was issued on 19 April and is current for 19-20 Apr. Maximum Usable Frequencies (MUFs) in the Australian region on UT day 19-Apr were initially near predicted monthly values, but became depressed over the UT day due to ongoing geomagnetic activity. Depressions of up to 35% were recorded across the Northern Australian region and at the Cocos Islands during local night and dawn hours. Depressions of 20-25% were also reported across the Southern Australian region, as well as the Antarctic region and Niue Island. Strong spread-F was present in the southern Australian region, and sporadic-E was recorded at Canberra and Norfolk Island. MUFs are expected to remain depressed by 15-20% for UT day 20-Apr due to the ongoing geomagnetic activity, before trending towards predicted monthly values over 21-22 Apr. ----------------------------------------------------------- 5. SPACE ENVIRONMENT SUMMARY GOES satellite data for 18 Apr Daily Proton Fluence >1 MeV: 1.8E+06 Daily Proton Fluence >10 MeV: 1.7E+04 Daily Electron Fluence >2 MeV: 1.10E+07 (normal fluence) Electron Fluence Daily Deep Dielectric Discharge Probability: 2% Fluence (flux accumulation over 24hrs)/ cm2-ster-day. X-ray background: B3.0 DSCOVR Satellite Solar Wind Day Averaged Data for 18 Apr Speed: 490 km/sec Density: 5.4 p/cc Temp: 190000 K Bz: -1 nT (Courtesy Space Weather Prediction Center, Boulder USA) -----------------------------------------------------------