[Ips-dsgr] ASWFC Daily Report - 17 May 26 issued 2330 UT on 17 May 2026 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Mon May 18 09:30:50 AEST 2026
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/17 MAY 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 17 MAY AND FORECAST FOR 18 MAY - 20 MAY
STATUS INDICATORS SOL:** YELLOW ** MAG:** YELLOW ** ION: ** YELLOW **
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 17 May: R1
Flares Max Fadeout Freq. Sectors
M1.4 0339UT possible lower E. Asia/Aust.
Observed 10.7 cm flux/Equivalent Sunspot Number for 17 May: 104/53
1B. SOLAR FORECAST
18 May 19 May 20 May
Activity R0, chance of R1 R0, chance of R1 R0, chance of R1
Fadeouts Possible Possible Possible
10.7cm/SSN 105/54 110/60 115/66
COMMENT: Solar flare activity on UT day 17-May was at the R1
level due to an M1.4 flare at 17/0339UT. There are currently
six numbered sunspot regions visible on the solar disk. The one
M-class flare of the day was produced by a region which has rotated
off the western limb. There are no large or magnetically complex
sunspot regions visible on the solar disk. AR4441 (N08E16, beta),
AR4442 (S16E47, alpha) and AR4443 (S16E63, alpha) all showed
spot development over the UT day. All other regions are stable.
Solar flare activity is expected to be at the R0 level over 18-20
May, with a chance of R1. S0 solar radiation storm conditions
were observed on UT day 17-May. S0 solar radiation storm conditions
are expected over 18-20 May. No geoeffective CMEs were observed
on 17-May. The solar wind speed declined over the UT day 17-May,
mostly ranging between 540 and 730 km/s . The wind speed is currently
at around 550 km/s. The peak total interplanetary magnetic field
strength (IMF, Bt) was 5 nT and the north-south IMF component
(Bz) range was -3 to +3 nT. The solar wind speed is expected
to continue to decline on 18-May until the anticipated arrival
of a CME first observed on 16-May causes an increase. A general
decline in wind speed is expected over 19-20 May.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 17 May: G0
Estimated Indices 17 May : A K
Australian Region 7 22232221
Cocos Island 4 11222210
Darwin 6 22222221
Townsville 7 22232221
Learmonth 8 22323220
Alice Springs 6 22222220
Gingin 9 22233231
Canberra 6 22232120
Kennaook Cape Grim 8 22133221
Hobart 7 22232221
Estimated Antarctic Regional K Indices 17 May :
Macquarie Island 10 12234230
Casey 14 34323332
Mawson 26 34544352
Observed Regional daily pc3 Indices 17 May :
Darwin 2 (Quiet)
Townsville 0 (Quiet)
Learmonth 10 (Quiet)
Alice Springs 0 (Quiet)
Gingin 77 (Active)
Canberra 74 (Active)
Hobart 55 (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 17 May : A
Fredericksburg 11
Planetary 13
Observed AFr/Ap Indices 16 May : A K
Fredericksburg 19
Planetary 34 6554 2543
2B. MAGNETIC FORECAST
Date Ap Conditions
18 May 22 G1, chance of G2
19 May 19 G0-G1
20 May 12 G0
COMMENT: ASWFC Geomagnetic Warning 33 was issued on 17 May and
is current for 18-19 May. G0 geomagnetic conditions were observed
in the Australian region on 17-May. Mostly G0 conditions were
observed in the Antarctic region, with G1 conditions observed
at Mawson. G1 conditions, with a chance of G2 are expected on
18-May and G0-G1 conditions are expected on 19-May due to an
anticipated CME impact in the second half of 18-May. G0 conditions
are expected on 20-May,
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
17 May Normal Normal Normal-fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
18 May Normal Normal-fair Fair
19 May Normal Normal-fair Fair
20 May Normal Normal Normal-fair
COMMENT: Global ionospheric conditions were mostly normal to
fair over UT day 16-May, with some degraded conditions observed
at higher latitudes. Mostly normal conditions are expected for
most of 18-May. Mild degradations are possible from late on 18-May
through 19-May due to anticipated geomagnetic activity. Conditions
are expected to recover towards normal on 20-May.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
17 May 48
Observed Australian Regional MUFs
Cocos Island Region:
No data available during local day.
No data available during local night.
Niue Island Region:
Depressed by 15% during local day.
Depressed by 35% during local night.
Northern Australian Region:
Near predicted monthly values during local day.
Depressed by 15% during local night.
Southern Australian Region:
Depressed by 20% during local day.
Depressed by 20% during local night.
Antarctic Region (Casey/Davis/Mawson):
Depressed by 20% 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
18 May 45 Depressed 15%/near predicted monthly values
19 May 45 Depressed 15%/near predicted monthly values
20 May 54 Near predicted monthly values
COMMENT: Maximum Usable Frequencies (MUFs) were near predicted
monthly values in the northern Australian region during local
day, but depressed by up to 15% during local night. MUFs were
depressed by up to 20% in the southern Australian region throughout
the day. Significant spread-F was observed at Hobart and Canberra
during local night hours. MUFs are expected to be near predicted
monthly values in the first half of 18-May, with depressions
of up to 15% expected possible from late on 18-May through 19-May
due to anticipated geomagnetic activity. Conditions are expected
to recover towards predicted monthly values on 20-May.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 16 May
Daily Proton Fluence >1 MeV: 5.3E+06
Daily Proton Fluence >10 MeV: 1.8E+04
Daily Electron Fluence >2 MeV: 4.50E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 6%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B4.1
DSCOVR Satellite Solar Wind Day Averaged Data for 16 May
Speed: 667 km/sec Density: 2.1 p/cc Temp: 235000 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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