[Ips-dsgr] ASWFC Daily Report - 18 October 25 issued 2332 UT on 18 Oct 2025 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Sun Oct 19 10:32:40 AEDT 2025
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/18 OCTOBER 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 18 OCTOBER AND FORECAST FOR 19 OCTOBER - 21 OCTOBER
STATUS INDICATORS SOL:** RED ** MAG:** RED ** ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 18 Oct: R1
Flares Max Fadeout Freq. Sectors
M1.0 0041UT possible lower West Pacific
M1.1 0239UT possible lower E. Asia/Aust.
M1.2 0639UT possible lower Mid East/Indian
M1.5 1051UT possible lower European
Observed 10.7 cm flux/Equivalent Sunspot Number for 18 Oct: 156/110
1B. SOLAR FORECAST
19 Oct 20 Oct 21 Oct
Activity R0-R1 R0-R1 R0-R1
Fadeouts Probable Probable Probable
10.7cm/SSN 150/105 155/109 160/114
COMMENT: Solar activity on UT day 18-Oct was at the R1 level
due to five low level M-class flares, the largest of which was
an M1.5 flare at 18/1051UT. There are currently six numbered
sunspot regions and one unnumbered region visible on the solar
disk. All the M-class flares of the UT day were produced by AR4246
(N24W81, beta-gamma) which rotated off the visible solar disk
over 18-Oct. AR4256 (S16E43, beta) showed spot development over
the UT day as did an unnumbered region visible at around S12E65
with beta magnetic classification. All other sunspot regions
are either stable or in decay. Solar activity is expected to
be at R0-R1 levels over 19-21 Oct. S0 solar proton conditions
were observed on UT day 18-Oct. S0 solar proton conditions are
expected over 19-21 Oct. Several east directed CMEs were observed
on 18-Oct, but none are considered geoeffective. The solar wind
speed on UT day 18-Oct increased, mostly ranging between 370
to 520 km/s and is currently near 500 km/s. The peak total interplanetary
magnetic field strength (IMF, Bt) was 21 nT and the north-south
IMF component (Bz) range was -12 to +13 nT. Two sustained periods
of mostly negative Bz conditions were observed from 18/0230UT
- 18/0650UT and 18/1520UT - 18/2020UT. The solar wind speed is
expected to remain elevated over 19-21 Oct due to current elevated
conditions combined with coronal hole high speed wind stream
effects from an equatorial coronal hole.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 18 Oct: G1
Estimated Indices 18 Oct : A K
Australian Region 27 45433453
Cocos Island 18 34332443
Darwin 22 44433443
Townsville 27 45433453
Learmonth 34 55433554
Alice Springs 26 35433453
Gingin 29 44433463
Canberra 24 44432453
Kennaook Cape Grim 29 45443453
Hobart 29 45443453
Estimated Antarctic Regional K Indices 18 Oct :
Macquarie Island 42 34553664
Casey 37 56543353
Mawson 39 45644363
Observed Regional daily pc3 Indices 18 Oct :
Darwin 2 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 14 (Quiet)
Canberra 53 (Unsettled)
Hobart 84 (Minor storm)
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 18 Oct : A
Fredericksburg 23
Planetary 33
Observed AFr/Ap Indices 17 Oct : A K
Fredericksburg 8
Planetary 9 2233 2312
2B. MAGNETIC FORECAST
Date Ap Conditions
19 Oct 35 G1, chance of G2
20 Oct 18 G0, chance of G1
21 Oct 10 G0
COMMENT: ASWFC Geomagnetic Warning 81 was issued on 17 October
and is current for 17-19 Oct. Mostly G1 geomagnetic conditions
were observed in the Australian region on UT day 18-Oct, with
a period of G2 conditions at Gingin. G2 conditions were observed
at the planetary level and in the Antarctic region. G1 geomagnetic
conditions, with a chance of G2 are expected on 19-Oct due to
current elevated IMF conditions, combined with anticipated coronal
hole high speed wind stream effects. G0 conditions, with a chance
of G1 are expected on 20-Oct and G0 conditions are expected on
21-Oct as conditions ease.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
18 Oct Normal Fair-normal Fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
19 Oct Fair Fair Fair-poor
20 Oct Normal Normal-fair Fair
21 Oct Normal Normal Normal-fair
COMMENT: HF radio propagation conditions on UT day 18-Oct were
mildly degraded in the first half of the UT day at mid and high
latitudes. Conditions eased to normal over the UT day. Mostly
fair HF conditions are expected on 19-Oct, with conditions easing
towards normal over 20-21 Oct. Shortwave fadeouts are possible.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
18 Oct 99
Observed Australian Regional MUFs
Cocos Island Region:
Enhanced by 30% during local day.
Enhanced by 15% during local night.
Niue Island Region:
Enhanced by 15% during local day.
Enhanced by 15% during local night.
Northern Australian Region:
Near predicted monthly values.
Southern Australian Region:
Depressed by 15% during local day.
Near predicted monthly values during local night.
Depressed by 35% after local dawn.
Antarctic Region (Casey/Davis/Mawson):
Depressed by 15% over the UT day.
Monthly T index:
Month T index
Sep 109
Oct 89
Nov 89
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
19 Oct 90 Near predicted monthly values/depressed 5 to
15%
20 Oct 94 Near predicted monthly values
21 Oct 100 Near predicted monthly values
COMMENT: ASWFC SWF HF Communications Warning 95 was issued on
18 October and is current for 18-19 Oct. Maximum usable frequencies
(MUFs) in the Australian region on UT day 18-Oct were mostly
near predicted monthly values in the northern Australian region
and during local night in the southern Australian region. Conditions
were depressed by 15-35% during local daylight hours in the southern
Australian region. MUFs are expected to be near predicted monthly
values to 15% depressed on 19-Oct and near predicted monthly
values over 20-21 Oct. Shortwave fadeouts are possible.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 17 Oct
Daily Proton Fluence >1 MeV: 1.2E+06
Daily Proton Fluence >10 MeV: 1.6E+04
Daily Electron Fluence >2 MeV: 6.80E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 8%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: C3.0
DSCOVR Satellite Solar Wind Day Averaged Data for 17 Oct
Speed: 390 km/sec Density: 8.4 p/cc Temp: 30100 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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