[Ips-dsgr] ASWFC Daily Report - 17 August 26 issued 2330 UT on 17 Aug 2026 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Tue Aug 18 09:30:47 AEST 2026
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/17 AUGUST 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 17 AUGUST AND FORECAST FOR 18 AUGUST - 20 AUGUST
STATUS INDICATORS SOL:** YELLOW ** MAG:** YELLOW ** ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 17 Aug: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 17 Aug: 124/77
1B. SOLAR FORECAST
18 Aug 19 Aug 20 Aug
Activity R0 R0 R0
Fadeouts Possible Possible Possible
10.7cm/SSN 125/78 130/84 130/84
COMMENT: Solar flare activity on UT day 17-Aug was at the R0
level, with several minor C-class flares observed. There are
currently four numbered active regions (ARs) visible on the solar
disk and one unnumbered region. AR 4507 (N05W41, beta-gamma)
is the largest and most magnetically complex region on the solar
disk, but has no history of flaring above the C-class level.
This region and 4506 (N11W58, beta-gamma) showed trailer spot
development over the UT day. All other regions are either stable
or in decay. An unnumbered region has developed on the solar
disk at around N10W65, close to the recently decayed 4510, with
apparent beta magnetic complexity. Solar flare activity is expected
to be at R0-R1 levels over 18-20 Aug, primarily due to the size
and magnetic complexity of region 4507. S0 solar radiation storm
conditions were observed on UT day 17-Aug and are expected to
remain there over 18-20 Aug. No significantly Earth-directed
coronal mass ejections (CMEs) have been observed. An east directed
CME is visible in STEREO-A coronagraph imagery from 17/0753UT
and in GOES-19 and SOLAR-1 coronagraph imagery from 17/0730UT.
This CME is potentially associated with an eruption on the disk
at around N10W60, observed from 17/0622UT in GOES SUVI, SDO and
H-Alpha imagery. Analysis of this CME was complicated by a lack
of SOHO coronagraph imagery of the event. Preliminary modelling
suggests the chance of a glancing impact with Earth on 21-Aug
at 0100UT. Further analysis will be performed when more coronagraph
imagery is available. A series of eruptions on the disk at around
N10W63 are visible in GOES SUVI, SDO and H-Alpha imagery from
17/1651UT. A narrow CME directed to the west is visible in GOES-19
and SOLAR-1 coronagraph imagery from 17/1900UT. This CME is not
considered geoeffective. The solar wind speed increased slightly
over the UT day, mostly ranging between 300 km/s and 400 km/s
and is currently at around 395 km/s. The peak total interplanetary
magnetic field strength (IMF, Bt) was 14 nT and the north-south
IMF component (Bz) range was -12 to +10 nT. The solar wind speed
is expected to remain at current levels on 18-Aug. An increase
is expected over 19-20 Aug due to high speed wind stream effects
from a pair of coronal holes rotating towards geoeffective positions.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 17 Aug: G0
Estimated Indices 17 Aug : A K
Australian Region 4 11111222
Cocos Island 4 11111222
Darwin 7 22212223
Townsville 8 22212233
Learmonth 7 11112233
Alice Springs 5 11112222
Gingin 6 11201233
Canberra 4 11111222
Kennaook Cape Grim 4 01111222
Hobart 4 11111222
Estimated Antarctic Regional K Indices 17 Aug :
Macquarie Island 3 00221111
Casey 9 33212123
Mawson 21 32324236
Observed Regional daily pc3 Indices 17 Aug :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 0 (Quiet)
Canberra 0 (Quiet)
Hobart 0 (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 17 Aug : A
Fredericksburg 8
Planetary 10
Observed AFr/Ap Indices 16 Aug : A K
Fredericksburg 0
Planetary 2 1222 0011
2B. MAGNETIC FORECAST
Date Ap Conditions
18 Aug 10 G0
19 Aug 16 G0-G1
20 Aug 12 G0, chance of G1
COMMENT: G0 geomagnetic conditions were observed at the planetary
level and in the Australian region on UT day 17-Aug. Mostly G0
conditions were observed in the Antarctic region, with a period
of G2 observed at Mawson. G0 planetary geomagnetic conditions
are expected on 18-Aug. G0-G1 conditions are expected on 19-Aug
due to high speed wind stream effects from a coronal hole in
the southern hemisphere rotating towards a geoeffective position.
G0 conditions, with a chance of G1 are expected on 20-Aug due
to ongoing coronal hole high speed wind effects.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
17 Aug Normal-fair Normal Normal
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
18 Aug Normal Normal Normal-fair
19 Aug Normal Normal-fair Fair
20 Aug Normal Normal Normal-fair
COMMENT: HF radio propagation conditions on UT day 17-Aug were
mostly normal, with some degradations observed in the northern
hemisphere and at low latitudes. HF radio propagation conditions
are expected to be mostly normal over 18-Aug. Normal to fair
conditions are expected on 19-Aug due to forecast geomagnetic
activity, with degradations most likely at high latitudes. A
recovery towards normal is expected on 20-Aug.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
17 Aug 63
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 20% during local night.
Northern Australian Region:
Near predicted monthly values.
Southern Australian Region:
Near predicted monthly values.
Antarctic Region (Casey/Davis/Mawson):
Enhanced by 15% over the UT day.
Monthly T index:
Month T index
Jul 75
Aug 64
Sep 61
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
18 Aug 60 Near predicted monthly values
19 Aug 50 Near predicted monthly values
20 Aug 50 Near predicted monthly values
COMMENT: Maximum usable frequencies (MUFs) in the Australian
region on UT day 17-Aug were near predicted monthly values. Spread
F was observed at Hobart during local night hours. MUFs are expected
to be near predicted monthly values over 18-20 Aug.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 16 Aug
Daily Proton Fluence >1 MeV: 5.5E+04
Daily Proton Fluence >10 MeV: 2.0E+04
Daily Electron Fluence >2 MeV: 1.60E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 3%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B8.4
DSCOVR Satellite Solar Wind Day Averaged Data for 16 Aug
Speed: 324 km/sec Density: 2.6 p/cc Temp: 46300 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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