[Ips-dsgr] ASWFC Daily Report - 20 August 26 issued 2330 UT on 20 Aug 2026 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Fri Aug 21 09:30:51 AEST 2026
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/20 AUGUST 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 20 AUGUST AND FORECAST FOR 21 AUGUST - 23 AUGUST
STATUS INDICATORS SOL:** RED ** MAG:GREEN ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 20 Aug: R2
Flares Max Fadeout Freq. Sectors
M1.8 0805UT possible lower Mid East/Indian
M8.1 1142UT probable lower European
M2.9 1611UT possible lower South American/
Atlantic
Observed 10.7 cm flux/Equivalent Sunspot Number for 20 Aug: 125/78
1B. SOLAR FORECAST
21 Aug 22 Aug 23 Aug
Activity R1-R2 R1-R2 R1-R2
Fadeouts Probable Probable Probable
10.7cm/SSN 125/78 120/72 120/72
COMMENT: Solar flare activity on UT day 20-Aug was at the R2
level due to an M8.1 flare at 20/1142UT produced by Active Region
(AR) 4513 (N04E65, beta). This region also produced two flares
at the R1 level over the UT day. There are currently four numbered
sunspot regions visible on the solar disk and one unnumbered
region. Region 4513 was the most flare active over the UT day
and has shown spot growth in its leader spots. AR 4507 (N05W78,
beta) has shown decay in its intermediate spots and will soon
rotate beyond the western limb. Region 4514 (S10W51, beta) has
exhibited mild spot growth over the 24-hour period. An unnumbered
region recently rotated over the eastern limb near S09E80 (alpha)
and appears stable. All other regions are either stable or in
decay. Solar flare activity is expected to be at R1-R2 levels
over 21-23 Aug due to the observed flare activity from region
4513. S0 solar radiation storm conditions were observed on UT
day 20-Aug. S0 solar radiation storm conditions are expected
over 21-23 Aug. No Earth-directed coronal mass ejections (CMEs)
have been observed. A west-directed CME was observed, visible
in STEREO-A coronagraph imagery from 20/1223UT. This CME is considered
to be associated with the aforementioned M8.1 flare from AR 4513.
Modelling indicates this CME will pass behind the Earth, with
no geoeffective component. An east-directed CME observed in LASCO
C2 coronagraph imagery at 20/1848UT is considered a farside event
and therefore not geoeffective. The solar wind speed on UT day
20-Aug mildly declined, ranging between 595 and 500 km/s, and
is currently near 525 km/s. The peak total interplanetary magnetic
field strength (IMF, Bt) was 7 nT and the north-south IMF component
(Bz) range was -5 to +5 nT. The solar wind speed is expected
to decline over 21-23 Aug due to waning coronal hole high speed
wind stream effects.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 20 Aug: G0
Estimated Indices 20 Aug : A K
Australian Region 7 22213122
Cocos Island 5 12212121
Darwin 7 22213122
Townsville 7 22213122
Learmonth 8 22213132
Alice Springs 7 22213122
Gingin 8 22213132
Canberra 7 22113222
Kennaook Cape Grim 7 22213122
Hobart 7 22113222
Estimated Antarctic Regional K Indices 20 Aug :
Macquarie Island 8 22214212
Casey 15 34423232
Mawson 44 64423375
Observed Regional daily pc3 Indices 20 Aug :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 19 (Quiet)
Canberra 50 (Unsettled)
Hobart 19 (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 Aug : A
Fredericksburg 10
Planetary 13
Observed AFr/Ap Indices 19 Aug : A K
Fredericksburg 15
Planetary 20 3544 3223
2B. MAGNETIC FORECAST
Date Ap Conditions
21 Aug 12 G0
22 Aug 8 G0
23 Aug 6 G0
COMMENT: ASWFC Geomagnetic Warning 51 was issued on 19 August
and is current for 19-21 Aug. G0 geomagnetic conditions were
observed in the planetary and Australian regions on UT day 20-Aug.
G3 geomagnetic conditions were observed in the Antarctic region.
G0 planetary geomagnetic conditions are expected over 21-23 Aug.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
20 Aug Normal Normal Normal-fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
21 Aug Normal Normal Normal-fair
22 Aug Normal Normal Normal-fair
23 Aug Normal Normal Normal
COMMENT: HF radio propagation conditions on UT day 20-Aug were
mostly normal. HF radio propagation conditions are expected to
be mostly normal over 21-23 Aug. Shortwave fadeouts are probable.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
20 Aug 73
Observed Australian Regional MUFs
Cocos Island Region:
No data available during local day.
No data available during local night.
Niue Island Region:
Mostly near predicted monthly values.
Northern Australian Region:
Near predicted monthly values.
Southern Australian Region:
Mostly near predicted monthly values.
Antarctic Region (Casey/Davis/Mawson):
Depressed by 15% over the UT day.
Monthly T index:
Month T index
Jul 75
Aug 64
Sep 61
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
21 Aug 75 Near predicted monthly values
22 Aug 75 Near predicted monthly values
23 Aug 75 Near predicted monthly values
COMMENT: ASWFC SWF HF Communications Warning 75 was issued on
20 August and is current for 20-22 Aug. Maximum usable frequencies
(MUFs) in the Australian region on UT day 20-Aug were near predicted
monthly values. Spread F was observed at Hobart and Perth during
local night hours. MUFs are expected to be near predicted monthly
values over 21-23 Aug. Shortwave fadeouts are probable.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 19 Aug
Daily Proton Fluence >1 MeV: 4.8E+05
Daily Proton Fluence >10 MeV: 2.0E+04
Daily Electron Fluence >2 MeV: 1.70E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 3%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B9.4
Solar Wind Day Averaged Data for 19 Aug
Speed: 562 km/sec Density: 6.7 p/cc Temp: 264000 K Bz: 0 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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