[Ips-dsgr] ASWFC Daily Report - 23 April 26 issued 2330 UT on 23 Apr 2026 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Fri Apr 24 09:30:51 AEST 2026
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/23 APRIL 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 23 APRIL AND FORECAST FOR 24 APRIL - 26 APRIL
STATUS INDICATORS SOL:** YELLOW ** MAG:** RED ** ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 23 Apr: R1
Flares Max Fadeout Freq. Sectors
M1.6 0435UT possible lower E. Asia/Aust.
M4.3 0848UT possible lower Mid East/Indian
M1.7 1400UT possible lower South American/
Atlantic
M4.9 1708UT possible lower South American/
Atlantic
Observed 10.7 cm flux/Equivalent Sunspot Number for 23 Apr: 128/81
1B. SOLAR FORECAST
24 Apr 25 Apr 26 Apr
Activity R1, chance of R2 R1, chance of R2 R1, chance of R2
Fadeouts Possible Possible Possible
10.7cm/SSN 135/89 135/89 132/86
COMMENT: Solar flare activity reached the R1 level on UT day
23-Apr, with five M-class flares observed throught the UT day.
The largest of these flares was an M4.9 flare from AR 4419 (N15W64,
beta), peaking at 23/1708UT. AR 4419 also produced an M1.6, an
M4.3, and an M1.7 flare, which peaked at 23/0435UT, 23/0848UT,
and 23/1400UT, respectively. Additionally, an M1.2 flare from
AR 4420 (N16E26, beta-gamma) peaking at 23/0459UT was also observed.
There are currently four numbered and two unnumbered regions
on the solar disk, with AR 4420 being the largest and most magnetically
complex. This region continued to exhibit some growth across
the UT day. Flare-active AR 4419 also displayed some minor growth
as it rotates toward the western limb of the Sun. Two new active
regions appeared and exhibited growth over the last 24 hours
at S05E47 and N14E58, with both appearing to exhibit beta magnetic
classifications, although analysis is affected by foreshortening
effects. All other regions are either stable or in decay. Solar
flare activity over 24-26 Apr is forecast at the R1 level, with
a chance of R2, due to ongoing growth and flare activity from
AR 4419 and AR 4420, as well as potential activity from regions
rotating over the eastern solar limb. Solar proton conditions
were at the S0 level throughout 23-Apr. S0 conditions, with a
slight chance of S1, are forecast for 24-26 Apr, given the ongoing
solar activity over the last 24 hours from active regions in
geoeffective positions. Coronal mass ejections (CMEs) were associated
with each of the five M-class flares observed on UT day 23-Apr.
A north-east directed medium-velocity CME associated with the
M1.2 flare from AR 4420 was observed in SOHO/LASCO beginning
at 23/0512UT. Modelling of this event indicates a glancing impact,
with a forecast arrival at Earth on 26-Apr at 0300 +/-10 hours.
The four CMEs associated with flares from AR 4419 were all modelled
to miss the Earth. The solar wind continued a declining trend
over UT day 23-Apr, declining from about 490 km/s to 420 km/s
across the UT day. The interplanetary magnetic field strength
(IMF, Bt) peaked at 6 nT, with the north-south component (Bz)
ranging between -5 and +4 nT. The solar wind speed is expected
to continue to decline over 24-Apr, with an increase expected
on 25-Apr due to a small equatorial coronal hole. The solar wind
speed will then increase further on 26-Apr due to the anticipated
arrival of the CME first observed at 23/0512UT.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 23 Apr: G0
Estimated Indices 23 Apr : A K
Australian Region 3 12111101
Cocos Island 1 11110100
Darwin 2 200-1102
Townsville 5 22221112
Learmonth 5 22221211
Alice Springs 3 12211101
Gingin 3 22111100
Canberra 3 12111101
Kennaook Cape Grim 3 12211101
Hobart 4 12211111
Estimated Antarctic Regional K Indices 23 Apr :
Macquarie Island 3 12211100
Casey 10 34411101
Mawson 16 54431210
Observed Regional daily pc3 Indices 23 Apr :
Darwin 35 (Quiet to unsettled)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 4 (Quiet)
Canberra 20 (Quiet)
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 23 Apr : A
Fredericksburg 9
Planetary 10
Observed AFr/Ap Indices 22 Apr : A K
Fredericksburg 4
Planetary 5 2112 212-
2B. MAGNETIC FORECAST
Date Ap Conditions
24 Apr 8 G0
25 Apr 14 G0, chance of G1
26 Apr 26 G1-G2
COMMENT: G0 geomagnetic conditions were observed in the Australian
region on UT day 23-Apr, with G0 conditions reported at the planetary
scale. A single G1 interval was recorded in the Antarctic region
at Mawson. G0 geomagnetic conditions are forecast for 24-Apr,
rising to G0 with a chance of G1 on 25-Apr due to a small equatorial
coronal hole. G1-G2 conditions are forecast for 26-Apr due to
the combined effects of the coronal hole high speed wind stream
as well as the arrival of a CME first observed at 23/0512UT.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
23 Apr Fair-normal Fair-normal Fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
24 Apr Normal-fair Normal-fair Fair-normal
25 Apr Normal-fair Normal-fair Fair-normal
26 Apr Fair Fair Fair
COMMENT: Global ionospheric conditions were fair to normal on
UT day 23-Apr, with conditions generally improving throughout
the UT day. Ionospheric conditions in high latitude regions were
generally fair. Ionospheric conditions are expected to be normal
to fair across 24-25 Apr, before trending toward fair conditions
on 26-Apr due to forecast geomagnetic activity. Shortwave fadeouts
are possible.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
23 Apr 55
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 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:
Near predicted monthly values during local day.
Depressed by 30% during local night.
Antarctic Region (Casey/Davis/Mawson):
Near predicted monthly values over the UT day.
Monthly T index:
Month T index
Mar 92
Apr 83
May 81
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
24 Apr 70 Near predicted monthly values
25 Apr 75 Near predicted monthly values
26 Apr 80 Near predicted monthly values
COMMENT: Maximum Usable Frequencies (MUFs) in the Australian
region were near predicted monthly values during local daylight
hours, with depressions of 20-30% reported during local night
hours. Spread-F was observed at Canberra, and sporadic-E was
observed at Darwin during local night hours. MUFs are expected
to remain near monthly predicted values over 24-25 Apr, with
depressions likely on 26-Apr due to forecast geomagnetic activity.
Mild depressions are possible during local night hours, and shortwave
fadeouts are possible.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 22 Apr
Daily Proton Fluence >1 MeV: 4.0E+05
Daily Proton Fluence >10 MeV: 1.8E+04
Daily Electron Fluence >2 MeV: 2.10E+08 (moderate fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability:16%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B5.5
DSCOVR Satellite Solar Wind Day Averaged Data for 22 Apr
Speed: 493 km/sec Density: 1.8 p/cc Temp: 126000 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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