[Ips-dsgr] ASWFC Daily Report - 21 August 26 issued 2337 UT on 21 Aug 2026 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Sat Aug 22 09:37:22 AEST 2026
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/21 AUGUST 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 21 AUGUST AND FORECAST FOR 22 AUGUST - 24 AUGUST
STATUS INDICATORS SOL:** RED ** MAG:GREEN ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 21 Aug: R1
Flares Max Fadeout Freq. Sectors
M1.6 1001UT possible lower European
Observed 10.7 cm flux/Equivalent Sunspot Number for 21 Aug: 126/79
1B. SOLAR FORECAST
22 Aug 23 Aug 24 Aug
Activity R0-R1 R0-R1 R0-R1
Fadeouts Probable Probable Probable
10.7cm/SSN 120/72 120/72 115/66
COMMENT: Solar flare activity on UT day 21-Aug was at the R1
level due to a long duration M1.6 flare observed at 21/1018UT.
There are currently six numbered active regions (ARs) visible
on the solar disk. AR 4507 (N04W82, beta) is responsible for
the M1.6 flare at 21/1018UT but has almost completely rotated
off the visible disk. 4511 (S18W44, beta) showed spot development,
but remains magnetically simple and small. 4513 (N04W58, beta-gamma)
is the largest and most magnetically complex region on the solar
disk, but was flare quiet over the UT day. All other ARs are
stable. Solar flare activity is expected to be at R0-R1 levels
over 22-24 Aug due to the magnetic complexity and recent flare
activity from region 4513. S0 solar radiation storm conditions
were observed on UT day 21-Aug, although the > 10MeV flux as
measured at GOES increased over the UT-day. S0 conditions, with
a chance of S1 are expected on 22-Aug. S0 conditions are expected
over 23-24 Aug. The reason for the increase is likely the long
duration M1.6 flare at 21/1018UT and the concurrent CME. No Earth-directed
coronal mass ejections (CMEs) have been observed. A fast, west
directed CME was observed in SOHO and STEREO-A imagery from 21/0936UT.
This CME is associated with the M1.6 flare at 21/1018UT and a
concurrent eruption at around N05W80 visible in GOES SUVI, SDO
and H-Alpha imagery. Modelling suggests this CME will impact
the STEREO-A satellite at 22/2000UT but will pass ahead of the
Earth. The solar wind speed on UT day 21-Aug decreased slightly,
ranging between 450 and 560 km/s, and is currently near 470 km/s.
The peak total interplanetary magnetic field strength (IMF, Bt)
was 5 nT and the north-south IMF component (Bz) range was -4
to +4 nT. The solar wind speed is expected to continue to decline
over 22-24 Aug as coronal hole high speed wind stream effects
wane.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 21 Aug: G0
Estimated Indices 21 Aug : A K
Australian Region 4 22211011
Cocos Island 2 12111010
Darwin 4 22211012
Townsville 5 23211012
Learmonth 3 22101011
Alice Springs 4 22211011
Gingin 3 22101021
Canberra 4 22220011
Kennaook Cape Grim 4 22121011
Hobart 5 32221011
Estimated Antarctic Regional K Indices 21 Aug :
Macquarie Island 4 22221001
Casey 9 33322122
Mawson 14 54212123
Observed Regional daily pc3 Indices 21 Aug :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 12 (Quiet)
Canberra 6 (Quiet)
Hobart 6 (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 21 Aug : A
Fredericksburg 9
Planetary 11
Observed AFr/Ap Indices 20 Aug : A K
Fredericksburg 11
Planetary 11 3222 3233
2B. MAGNETIC FORECAST
Date Ap Conditions
22 Aug 6 G0
23 Aug 6 G0
24 Aug 4 G0
COMMENT: G0 geomagnetic conditions were observed at the planetary
level and Australian region on UT day 21-Aug. Mostly G0 conditions
were observed in the Antarctic region, with a period of G1 observed
at Mawson. G0 planetary geomagnetic conditions are expected over
22-24 Aug.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
21 Aug Normal Normal Normal-fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
22 Aug Normal Normal Normal
23 Aug Normal Normal Normal
24 Aug Normal Normal Normal
COMMENT: HF radio propagation conditions on UT day 21-Aug were
mostly normal, with some degradations observed at low and high
latitudes in the northern hemisphere. HF radio propagation conditions
are expected to be mostly normal over 22-24 Aug. Shortwave fadeouts
are possible.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
21 Aug 78
Observed Australian Regional MUFs
Cocos Island Region:
No data available during local day.
No data available during local night.
Niue Island Region:
Enhanced by 15% during local day.
Depressed by 20% during local night.
Enhanced by 30% after local dawn.
Northern Australian Region:
Near predicted monthly values.
Southern Australian Region:
Near predicted monthly values during local day.
Enhanced by 20% during local night.
Antarctic Region (Casey/Davis/Mawson):
Near predicted monthly values 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
22 Aug 80 Near to 15% above predicted monthly values
23 Aug 80 Near to 15% above predicted monthly values
24 Aug 80 Near to 15% above 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 21-Aug were near predicted
monthly values, with enhancements observed in the southern Australian
region during local night hours. MUFs are expected to be near
predicted monthly values over 22-24 Aug. Shortwave fadeouts are
possible.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 20 Aug
Daily Proton Fluence >1 MeV: 1.7E+05
Daily Proton Fluence >10 MeV: 2.1E+04
Daily Electron Fluence >2 MeV: 3.40E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 5%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: C1.1
Solar Wind Day Averaged Data for 20 Aug
Speed: 548 km/sec Density: 4.7 p/cc Temp: 205000 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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