[Ips-dsgr] ASWFC Daily Report - 20 October 26 issued 2330 UT on 20 Oct 2026 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Wed Oct 21 10:30:45 AEDT 2026
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/20 OCTOBER 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 20 OCTOBER AND FORECAST FOR 21 OCTOBER - 23 OCTOBER
STATUS INDICATORS SOL:GREEN MAG:GREEN ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 20 Oct: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 20 Oct: 121/73
1B. SOLAR FORECAST
21 Oct 22 Oct 23 Oct
Activity R0, chance of R1 R0, chance of R1 R0, chance of R1
Fadeouts None expected None expected None expected
10.7cm/SSN 120/72 118/70 115/66
COMMENT: Solar flare activity on UT day 20-Oct was at the R0
level, with several low-level C-class flares observed. There
are currently three numbered sunspot regions visible on the solar
disk. Active Region (AR) 4551 (S15W70, beta) is the largest region
on the disk and has shown decay in its intermediate spots. Region
4557 (N06W39, beta) has exhibited mild development in its intermediate
spots. AR 4560 (N13W14, beta) has shown spot growth across the
UT day. Solar flare activity is expected to be at the R0 level
over 21-23 Oct, with a chance of R1 due to the size and observed
flare activity of region 4551. S0 solar radiation storm conditions
were observed on UT day 20-Oct. S0 solar radiation storm conditions
are expected over 21-23 Oct. No Earth-directed coronal mass ejections
(CMEs) have been observed. The solar wind speed on UT day 20-Oct
increased, ranging between 320 and 440 km/s, and is currently
near 410 km/s. The peak total interplanetary magnetic field strength
(IMF, Bt) was 12 nT and the north-south IMF component (Bz) ranged
between -10 to +7 nT. A period of sustained southward IMF conditions
was observed over the interval 20/1240-1630UT. The solar wind
speed is forecast to remain elevated on 21-Oct due to ongoing
coronal hole high-speed wind stream effects. The solar wind speed
is expected to decrease over 22-23 Oct.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 20 Oct: G0
Estimated Indices 20 Oct : A K
Australian Region 6 11122322
Cocos Island 6 11122231
Darwin 7 21222223
Townsville 9 21233322
Learmonth 9 22223322
Alice Springs 7 21122322
Gingin 8 12122332
Canberra 7 11132322
Kennaook Cape Grim 7 11132322
Hobart 7 11132322
Estimated Antarctic Regional K Indices 20 Oct :
Casey 10 33331222
Mawson 19 22122364
Observed Regional daily pc3 Indices 20 Oct :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 0 (Quiet)
Canberra 0 (Quiet)
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 Oct : A
Fredericksburg 12
Planetary 16
Observed AFr/Ap Indices 19 Oct : A K
Fredericksburg 2
Planetary 3 0001 0011
2B. MAGNETIC FORECAST
Date Ap Conditions
21 Oct 12 G0
22 Oct 10 G0
23 Oct 6 G0
COMMENT: G0 geomagnetic conditions were observed in the Australian
region and at the planetary level on UT day 20-Oct. Mostly G0
geomagnetic conditions were observed in the Antarctic region,
with an isolated period of G2 observed at Mawson. G0 planetary
geomagnetic conditions are expected over 21-23 Oct.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
20 Oct Normal Normal Normal-fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
21 Oct Normal Normal Normal-fair
22 Oct Normal Normal Normal-fair
23 Oct Normal Normal Normal
COMMENT: Global high-frequency (HF) radio propagation conditions
were mostly normal on UT day 21-Oct, with some degradations observed
in northern hemisphere regions in the second half of the UT day.
Global HF propagation conditions are forecast to be mostly normal
over 21-23 Oct.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
20 Oct 63
Observed Australian Regional MUFs
Cocos Island Region:
No data available during local day.
No data available during local night.
Niue Island Region:
Near predicted monthly values during local day.
Enhanced by 20% during local night.
Northern Australian Region:
Mostly near predicted monthly values.
Southern Australian Region:
Near predicted monthly values.
Antarctic Region (Casey/Davis/Mawson):
Near predicted monthly values over the UT day.
Monthly T index:
Month T index
Sep 61
Oct 60
Nov 58
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
21 Oct 55 Near predicted monthly values
22 Oct 55 Near predicted monthly values
23 Oct 55 Near predicted monthly values
COMMENT: Maximum Usable Frequencies (MUFs) in the Australian
region were mostly near predicted monthly values on UT day 20-Oct.
Spread F was observed at Hobart during local night hours. MUFs
are forecast to be near predicted monthly values over 21-23 Oct.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 19 Oct
Daily Proton Fluence >1 MeV: 3.3E+05
Daily Proton Fluence >10 MeV: 2.1E+04
Daily Electron Fluence >2 MeV: 2.45E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 4%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B5.2
Solar Wind Day Averaged Data for 19 Oct
Speed: 376 km/sec Density: 2.6 p/cc Temp: 98900 K Bz: 3 nT
(Courtesy Space Weather Prediction Center, Boulder USA)
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Australian Space Weather Forecasting Centre
Bureau of Meteorology
ASWFC at bom.gov.au
www.bom.gov.au | www.sws.bom.gov.au
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