[Ips-dsgr] ASWFC Daily Report - 21 July 26 issued 2330 UT on 21 Jul 2026 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Wed Jul 22 09:30:50 AEST 2026
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/21 JULY 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 21 JULY AND FORECAST FOR 22 JULY - 24 JULY
STATUS INDICATORS SOL:** YELLOW ** MAG:** YELLOW ** ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 21 Jul: R1
Flares Max Fadeout Freq. Sectors
M3.4 20/2225UT possible lower East Pacific/
North American
M1.9 1727UT possible lower South American/
Atlantic
Observed 10.7 cm flux/Equivalent Sunspot Number for 21 Jul: 149/104
1B. SOLAR FORECAST
22 Jul 23 Jul 24 Jul
Activity R1, chance of R2 R1, chance of R2 R1, chance of R2
Fadeouts Possible Possible Possible
10.7cm/SSN 150/105 148/102 145/99
COMMENT: Solar flare activity on UT day 21-Jul reached the R1
level, due to an M1.9 flare peaking at 21/1727UT from Active
Region (AR) 4493 (N05W04, beta-gamma-delta). This region is the
largest and most magnetically complex of five on the visible
solar disk, and has continued to show growth over the past UT
day, including development of a second delta spot. All other
regions on the disk have remained mostly stable over the same
period. Solar flare activity is forecast to be at the R1 level
over 22-24 Jul, with a chance of R2, due to the magnetic complexity
and flare activity of AR 4493. S0 solar radiation storm conditions
were observed over 21-Jul, with the proton flux consistent with
background values. S0 solar radiation storm conditions are forecast
over 22-24 Jul. A faint, high-velocity, north-west-directed coronal
mass ejection (CME) was observed in SOHO/LASCO and STEREO/COR2
imaging from 21/1436UT, following flare activity from AR 4493.
Modelling of this CME suggests a glancing impact with Earth at
23/1500 +/- 12 hours, although confidence is reduced due to the
faint nature of the CME, as well as gaps in coronagraph imaging.
The solar wind speed increased over UT day 21-Jul, as the Earth
connected with a coronal hole high speed wind stream. The solar
wind speed began the day at ~280 km/s, and has increased to be
currently at 410-430 km/s. The interplanetary magnetic field
strength (IMF, Bt) peaked at 17 nT, with the north-south component
(Bz) ranging between -12 and +14 nT over the UT day, with extended
periods of southward Bz observed between 21/0610UT and 21/0836UT,
and between 21/1252UT and 21/1700UT. The solar wind is expected
to continue to increase over 22-24 Jul as the high speed wind
stream effects continue. An additional small discrete increase
in the solar wind speed may be observed on 23-Jul due to the
possible glancing impact of the previously mentioned CME first
observed on 21-Jul.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 21 Jul: G0
Estimated Indices 21 Jul : A K
Australian Region 9 12242321
Cocos Island 6 12231211
Darwin 7 22141211
Townsville 10 22242322
Learmonth 10 22242322
Alice Springs 9 12242311
Gingin 9 12242321
Canberra 9 12242311
Kennaook Cape Grim 9 12242321
Hobart 8 12232321
Estimated Antarctic Regional K Indices 21 Jul :
Macquarie Island 14 11352421
Casey 11 33232223
Mawson 29 22342565
Observed Regional daily pc3 Indices 21 Jul :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 0 (Quiet)
Canberra 0 (Quiet)
Hobart 2 (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 Jul : A
Fredericksburg 12
Planetary 15
Observed AFr/Ap Indices 20 Jul : A K
Fredericksburg 4
Planetary 4 1111 1111
2B. MAGNETIC FORECAST
Date Ap Conditions
22 Jul 24 G1, chance of G2
23 Jul 20 G1, chance of G2
24 Jul 15 G0, chance of G1
COMMENT: ASWFC Geomagnetic Warning 45 was issued on 21 July and
is current for 22-23 Jul. Geomagnetic conditions in the Australian
region were at the G0 level on UT day 21-Jul, with G0 conditions
also reported at the planetary level. G1-G2 conditions were reported
in the Antarctic region, as the effects of a coronal hole high
speed wind stream commenced. G1 geomagnetic conditions, with
a chance of G2, are forecast over 22-23 Jul due to the ongoing
coronal hole high speed wind stream effects, combined with a
possible glancing CME impact on 23-Jul. G0 geomagnetic conditions,
with a chance of G1, are forecast for 24-Jul as these effects
subside.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
21 Jul Normal Normal Normal-fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
22 Jul Fair Fair Fair
23 Jul Fair Fair Fair
24 Jul Normal-fair Normal-fair Normal-fair
COMMENT: Global high-frequency (HF) radio propagation conditions
were mostly normal on UT day 21-Jul, with some degradations in
high latitude regions in the northern hemisphere. Global HF propagation
conditions are forecast to be fair over 22-23 Jul due to forecast
geomagnetic activity. HF propagation conditions will then improve
to normal to fair on 24-Jul as these effects subside. Shortwave
fadeouts are possible.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
21 Jul 76
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.
Northern Australian Region:
Near predicted monthly values.
Southern Australian Region:
Near predicted monthly values during local day.
Enhanced by 25% during local night.
Antarctic Region (Casey/Davis/Mawson):
Near predicted monthly values over the UT day.
Monthly T index:
Month T index
Jun 81
Jul 66
Aug 63
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
22 Jul 50 Depressed 15%/near predicted monthly values
23 Jul 50 Depressed 15%/near predicted monthly values
24 Jul 65 Near predicted monthly values
COMMENT: ASWFC SWF HF Communications Warning 66 was issued on
21 July and is current for 21-22 Jul. Maximum Usable Frequencies
(MUFs) in the Australian region were near predicted values on
21-Jul, with some enhancements of up to 25% observed in the southern
Australian region during local night hours. Sporadic E was observed
in the northern Australian region, Norfolk Island, and Niue Island
during local night hours. MUFs are forecast to become depressed
by up to 15% over 22-23 Jul due to expected geomagnetic activity
over this period, before recovering to near predicted values
on 24-Jul. Shortwave fadeouts are possible.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 20 Jul
Daily Proton Fluence >1 MeV: 2.6E+05
Daily Proton Fluence >10 MeV: 1.8E+04
Daily Electron Fluence >2 MeV: 5.90E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 8%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: C1.0
DSCOVR Satellite Solar Wind Day Averaged Data for 20 Jul
Speed: 266 km/sec Density: 3.4 p/cc Temp: 29600 K Bz: -2 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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