[Ips-dsgr] ASWFC Daily Report - 31 May 26 issued 2330 UT on 31 May 2026 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Mon Jun 1 09:30:49 AEST 2026
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/31 MAY 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 31 MAY AND FORECAST FOR 01 JUNE - 03 JUNE
STATUS INDICATORS SOL:** YELLOW ** MAG:GREEN ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 31 May: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 31 May: 136/90
1B. SOLAR FORECAST
01 Jun 02 Jun 03 Jun
Activity R0, chance of R1 R0, chance of R1 R0, chance of R1
Fadeouts Possible Possible Possible
10.7cm/SSN 136/90 134/88 130/84
COMMENT: Solar flare activity on UT day 31-May was at the R0
level, with only C-class flares observed. There are currently
eight Active Regions (ARs) on the visible solar disk, with AR
4455 (N16E21, beta) being the largest. This region displayed
some minor decay in trailing spots over the last 24 hours. Region
4457 (S08W12, beta) exhibited some mild growth and spot redistribution
over the same period. All other regions are either stable or
in decay. Solar flare activity is forecast to be at the R0 level,
with a chance of R1 over 01-03 Jun. Solar radiation storm conditions
were at the S0 level on 31-May, with the solar proton flux consistent
with background values across the UT day. S0 solar radiation
conditions are forecast over 01-03 Jun. No geoeffective coronal
mass ejections (CMEs) were observed over the past UT day. A low-velocity,
south-west-directed CME first visible in SOHO/LASCO imaging from
31/1212UT, associated with a solar eruption observed in GOES/SUVI
304A imaging at 31/1136UT, was assessed to be a far side event,
and not geoeffective. The solar wind began the day elevated due
to effects from an equatorial coronal hole, with speeds ranging
between 450 to 550 km/s throughout much of 31-May. The solar
wind speed is expected to slowly decline over 01-02 Jun, as the
high speed wind stream effects from this coronal hole subside.
An increase is forecast to occur late on 03-Jun, as another equatorial
coronal hole moves into a geoeffective position.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 31 May: G0
Estimated Indices 31 May : A K
Australian Region 5 22211211
Cocos Island 3 12111110
Darwin 4 22211111
Townsville 6 23211211
Learmonth 6 22221221
Alice Springs 5 23211110
Gingin 7 22212231
Canberra 4 22111210
Kennaook Cape Grim 4 22111211
Hobart 4 22111211
Estimated Antarctic Regional K Indices 31 May :
Macquarie Island 5 22102310
Casey 9 33322221
Mawson 24 45422154
Observed Regional daily pc3 Indices 31 May :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 4 (Quiet)
Canberra 15 (Quiet)
Hobart 28 (Quiet to unsettled)
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 31 May : A
Fredericksburg 10
Planetary 12
Observed AFr/Ap Indices 30 May : A K
Fredericksburg 13
Planetary 15 3312 2244
2B. MAGNETIC FORECAST
Date Ap Conditions
01 Jun 8 G0
02 Jun 8 G0
03 Jun 12 G0, chance of G1
COMMENT: G0 geomagnetic conditions were observed in the Australian
region on UT day 31-May, with G0 conditions also reported at
the planetary level. Mostly G0 conditions were recorded in the
Antarctic region, with some G1 intervals observed at Mawson.
G0 geomagnetic conditions are forecast for the period 01-03 Jun,
with a chance of G1 on 03-Jun due to a high-speed wind stream
from an equatorial coronal hole expected to connect with Earth
on this date.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
31 May Normal Normal-fair Normal-fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
01 Jun Normal Normal Normal-fair
02 Jun Normal Normal Normal-fair
03 Jun Normal Normal Normal-fair
COMMENT: Global ionospheric conditions were normal-fair on UT
day 31-May, with some degradations observed at mid-latitudes
at different times of the day. Global ionospheric conditions
are expected to be mostly normal over 01-03 Jun, with some mild
degradations possible at high latitudes.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
31 May 90
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:
Enhanced by 25% during local day.
Near predicted monthly values during local night.
Southern Australian Region:
Near predicted monthly values.
Antarctic Region (Casey/Davis/Mawson):
Near predicted monthly values over the UT day.
Monthly T index:
Month T index
Apr 74
May 71
Jun 68
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
01 Jun 90 Near predicted monthly values
02 Jun 90 Near predicted monthly values
03 Jun 90 Near predicted monthly values
COMMENT: Maximum Usable Frequencies (MUFs) in the Australian
and Antarctic regions were near predicted monthly values over
UT day 31-May, with some enhancements seen in the northern Australian
region. Significant mixed spread-F was observed across the Australian
region during local night hours, with the most significant spread-F
observed in the southern Australian region. MUFs are expected
to remain near predicted values over 01-03 Jun, with some enhancements
of up to 15% possible.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 30 May
Daily Proton Fluence >1 MeV: 5.5E+05
Daily Proton Fluence >10 MeV: 2.0E+04
Daily Electron Fluence >2 MeV: 1.50E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 3%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B7.4
DSCOVR Satellite Solar Wind Day Averaged Data for 30 May
Speed: 423 km/sec Density: 2.0 p/cc Temp: 120000 K Bz: 1 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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