[Ips-dsgr] ASWFC Daily Report - 17 October 25 issued 2330 UT on 17 Oct 2025 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Sat Oct 18 10:30:57 AEDT 2025
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/17 OCTOBER 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 17 OCTOBER AND FORECAST FOR 18 OCTOBER - 20 OCTOBER
STATUS INDICATORS SOL:** RED ** MAG:** YELLOW ** ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 17 Oct: R1
Flares Max Fadeout Freq. Sectors
M1.0 16/2319UT possible lower West Pacific
M1.5 0128UT possible lower West Pacific
M1.1 1245UT possible lower European
M1.0 1432UT possible lower South American/
Atlantic
M1.3 1633UT possible lower South American/
Atlantic
M1.1 1903UT possible lower East Pacific/
North American
Observed 10.7 cm flux/Equivalent Sunspot Number for 17 Oct: 164/118
1B. SOLAR FORECAST
18 Oct 19 Oct 20 Oct
Activity R1-R2 R1-R2 R1-R2
Fadeouts Probable Probable Probable
10.7cm/SSN 165/119 155/109 160/114
COMMENT: Solar activity on UT day 17-Oct was at the R1 level
due to several M-class flares, the largest of which was an M1.5
flare at 17/0128UT produced by AR4246 (N24W79, beta-gamma). There
are currently eight numbered sunspot regions visible on the solar
disk. AR4246 is the most magnetically complex region on the disk.
This region appears to be decaying and will soon rotate over
the western limb. AR4252 (S13W04, beta) has shown recent growth
in its trailer spots. AR4256 (S16E55, beta) has exhibited growth
in its leader spots. Newly numbered AR4257 (S08E76, beta) recently
rotated over the eastern limb and appears stable. All other sunspot
regions are either stable or in decay. Solar activity is expected
to be at R1-R2 levels over 18-20 Oct. S0 solar proton conditions
were observed on UT day 17-Oct. S0 solar proton conditions are
expected over 18-20 Oct, with a chance of S1. Several CMEs were
observed, but none are considered geoeffective. The solar wind
speed on UT day 17-Oct mildly declined, ranging from 375 to 415
km/s and is currently near 390 km/s. The peak total interplanetary
magnetic field strength (IMF, Bt) was 14 nT and the north-south
IMF component (Bz) range was -9 to +11 nT. A mild step increase
was observed in the IMF, Bt parameter at 17/0933UT, potentially
indicative of a CME arrival, however no increase was observed
in the solar wind speed. The solar wind speed is expected to
remain near background levels on 18-Oct, then increase over 19-20
Oct due to coronal hole high speed wind stream effects from an
equatorial coronal hole.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 17 Oct: G0
Estimated Indices 17 Oct : A K
Australian Region 9 21233322
Cocos Island 8 11233321
Darwin 12 32233323
Townsville 11 21243322
Learmonth 11 22243322
Alice Springs 9 21233322
Gingin 10 31233321
Canberra 8 21332222
Kennaook Cape Grim 10 21343212
Hobart 8 21332221
Estimated Antarctic Regional K Indices 17 Oct :
Macquarie Island 13 10453211
Casey 13 33343222
Mawson 11 23333311
Observed Regional daily pc3 Indices 17 Oct :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 16 (Quiet)
Canberra 15 (Quiet)
Hobart 31 (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 17 Oct : A
Fredericksburg 13
Planetary 16
Observed AFr/Ap Indices 16 Oct : A K
Fredericksburg 3
Planetary 4 1121 1012
2B. MAGNETIC FORECAST
Date Ap Conditions
18 Oct 18 G0-G1
19 Oct 19 G0-G1
20 Oct 14 G0, chance of G1
COMMENT: ASWFC Geomagnetic Warning 81 was issued on 17 October
and is current for 17-19 Oct. G0 geomagnetic conditions were
observed in the Australian region on UT day 17-Oct. Mostly G0
geomagnetic conditions were observed in the Antarctic region,
with an isolated period of G1 observed at Macquarie Island. G0-G1
geomagnetic conditions are expected on 18-Oct due to the current
elevated IMF conditions. G0-G1 geomagnetic conditions are expected
on 19-Oct, declining to G0, with a chance of G1 on 20-Oct due
to coronal hole high speed wind stream effects from an equatorial
coronal hole.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
17 Oct Normal Normal Normal-fair
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
18 Oct Normal Normal-fair Fair
19 Oct Normal Normal-fair Fair
20 Oct Normal Normal Normal-fair
COMMENT: HF radio propagation conditions on UT day 17-Oct were
mostly normal. Normal to fair HF conditions are expected over
18-19 Oct. Mostly normal HF conditions are expected on 20-Oct.
Shortwave fadeouts are probable.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
17 Oct 105
Observed Australian Regional MUFs
Cocos Island Region:
Enhanced by 30% during local day.
Near predicted monthly values during local night.
Niue Island Region:
Near predicted monthly values.
Northern Australian Region:
Near predicted monthly values during local day.
Enhanced by 15% during local night.
Southern Australian Region:
Near predicted monthly values during local day.
Enhanced by 20% during local night.
Antarctic Region (Casey/Davis/Mawson):
Near predicted monthly values 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
18 Oct 105 Near to 15% above predicted monthly values
19 Oct 100 Near predicted monthly values
20 Oct 100 Near predicted monthly values
COMMENT: Maximum usable frequencies (MUFs) in the Australian
region on UT day 17-Oct were near predicted monthly values to
20% enhanced. MUFs are expected to be near predicted monthly
values to 15% enhanced on 18-Oct and near predicted monthly values
over 19-20 Oct. Shortwave fadeouts are probable.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 16 Oct
Daily Proton Fluence >1 MeV: 1.6E+06
Daily Proton Fluence >10 MeV: 1.7E+04
Daily Electron Fluence >2 MeV: 1.40E+08 (moderate fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability:13%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: C2.1
DSCOVR Satellite Solar Wind Day Averaged Data for 16 Oct
Speed: 429 km/sec Density: 3.2 p/cc Temp: 46800 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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