[Ips-dsgr] ASWFC Daily Report - 20 May 26 issued 2330 UT on 20 May 2026 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Thu May 21 09:30:50 AEST 2026
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
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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.
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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.
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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.
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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.
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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)
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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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