[Ips-dsgr] ASWFC Daily Report - 20 July 26 issued 2330 UT on 20 Jul 2026 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Tue Jul 21 09:30:50 AEST 2026
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/20 JULY 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 20 JULY AND FORECAST FOR 21 JULY - 23 JULY
STATUS INDICATORS SOL:** YELLOW ** MAG:** YELLOW ** ION: ** YELLOW **
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 20 Jul: R1
Flares Max Fadeout Freq. Sectors
M2.5 1436UT possible lower South American/
Atlantic
M1.1 1920UT possible lower East Pacific/
North American
M3.4 2225UT possible lower East Pacific/
North American
Observed 10.7 cm flux/Equivalent Sunspot Number for 20 Jul: 137/91
1B. SOLAR FORECAST
21 Jul 22 Jul 23 Jul
Activity R1, chance of R2 R1, chance of R2 R1, chance of R2
Fadeouts Possible Possible Possible
10.7cm/SSN 140/94 142/96 145/99
COMMENT: Solar flare activity on UT day 20-Jul was at the R1
level, with an M2.5 flare peaking at 20/1436UT, an M1.1 flare
peaking at 20/1920UT, and an M3.4 flare peaking at 20/2225UT.
All of these flares have originated from Active Region (AR) 4493
(N05E10, beta-gamma-delta), which is the most magnetically complex
region on the disk. This region is one of four numbered and two
unnumbered regions on the disk, and has continued to show growth
over the last UT day, including the development of a delta spot.
All other numbered regions are stable or in decay. Two new regions
have rotated onto the front side of the disk in the last 24 hours.
These regions are presently located at S25E68 and S05E87, and
both appear to have a beta magnetic classification. The latter
region may be the return of the previously flare-active region
4478. Solar flare activity is forecast to be at the R1 level
over 21-23 Jul, with a chance of R2, due to the continued growth
and ongoing flare activity of AR 4493. S0 solar radiation storm
conditions persisted throughout 20-Jul, with S0 conditions forecast
for 21-23 Jul. No Earth-directed coronal mass ejections (CMEs)
have been observed in coronagraph imagery over the past UT day.
A west-directed medium-velocity CME was observed in SOHO/LASCO
from 20/1236UT, with modelling indicating this will pass ahead
of the Earth. The solar wind environment was consistent with
background conditions over 20-Jul, with the solar wind speed
ranging between 260-290 km/s throughout the UT day. The interplanetary
magnetic field strength (IMF, Bt) peaked at 7 nT, with the north-south
component (Bz) ranging between -4 and +3 nT over the UT day.
The solar wind speed is expected to remain at background levels
over 21-Jul, before rising on 22-Jul due to a coronal hole high
speed wind stream connecting with Earth. The solar wind speed
will remain elevated on 23-Jul as the high speed wind stream
effects continue.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 20 Jul: G0
Estimated Indices 20 Jul : A K
Australian Region 0 00100000
Cocos Island 1 10110010
Darwin 0 01100000
Townsville 1 11100001
Learmonth 0 10100000
Alice Springs 0 00100001
Gingin 0 00100000
Canberra 1 11100000
Kennaook Cape Grim 1 01110000
Hobart 0 00000000
Estimated Antarctic Regional K Indices 20 Jul :
Macquarie Island 0 00010000
Casey 2 12100010
Mawson 9 11111125
Observed Regional daily pc3 Indices 20 Jul :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 0 (Quiet)
Canberra 0 (Quiet)
Hobart 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 Jul : A
Fredericksburg 4
Planetary 4
Observed AFr/Ap Indices 19 Jul : A K
Fredericksburg 4
Planetary 4 1111 1111
2B. MAGNETIC FORECAST
Date Ap Conditions
21 Jul 5 G0
22 Jul 24 G1, chance of G2
23 Jul 18 G0-G1
COMMENT: Geomagnetic conditions in the Australian region were
at the G0 level on UT day 20-Jul, with G0 conditions also reported
at the planetary level. Mostly G0 conditions were reported in
the Antarctic region, with an isolated G1 interval at Mawson.
G0 conditions are forecast for 21-Jul before rising to G1, with
a chance of G2 on 22-Jul due to the onset of a coronal hole high
speed wind stream. G0-G1 geomagnetic conditions are forecast
for 23-Jul due to the ongoing high speed wind stream effects.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
20 Jul Normal Normal Normal
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
21 Jul Normal Normal Normal
22 Jul Fair Fair Fair
23 Jul Fair-normal Fair-normal Fair-normal
COMMENT: Global high-frequency (HF) radio propagation conditions
were normal on UT day 20-Jul, with some mild degradations over
the equatorial South American region. Global HF conditions are
expected to be mostly normal on 21-Jul, before becoming degraded
late on 22-Jul due to forecast geomagnetic activity. Degraded
conditions are forecast for 23-Jul as these effects continue.
Shortwave fadeouts are possible.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
20 Jul 67
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 during local day.
Depressed by 15% during local night.
Southern Australian Region:
Mostly near predicted monthly values.
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
21 Jul 65 Near predicted monthly values
22 Jul 45 Depressed 15%/near predicted monthly values
23 Jul 55 Depressed 10%/near predicted monthly values
COMMENT: Maximum Usable Frequencies (MUFs) in the Australian
region on UT day 20-Jul were near predicted monthly values, with
overnight depressions up to 15% observed in the northern Australian
region. Spread-F was observed across the Australian region during
local night hours, with strong spread-F observed in Hobart, Perth,
Learmonth, and Townsville. Sporadic E was also observed in Learmonth
during local night hours. MUFs are forecast to be near predicted
monthly values on 21-Jul, with some depressions possible during
local night hours. MUFs are forecast to be up to 15% depressed
on 22-Jul due to anticipated geomagnetic activity, with depressions
of up to 10% possible on 23-Jul as geomagnetic activity continues.
Shortwave fadeouts are possible.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 19 Jul
Daily Proton Fluence >1 MeV: 1.6E+05
Daily Proton Fluence >10 MeV: 1.8E+04
Daily Electron Fluence >2 MeV: 5.70E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 7%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B7.2
DSCOVR Satellite Solar Wind Day Averaged Data for 19 Jul
Speed: 302 km/sec Density: 3.3 p/cc Temp: 56800 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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