[Ips-dsgr] ASWFC Daily Report - 16 April 26 issued 2330 UT on 16 Apr 2026 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Fri Apr 17 09:30:44 AEST 2026
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/16 APRIL 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 16 APRIL AND FORECAST FOR 17 APRIL - 19 APRIL
STATUS INDICATORS SOL:GREEN MAG:** YELLOW ** ION: ** YELLOW **
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 16 Apr: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 16 Apr: 108/58
1B. SOLAR FORECAST
17 Apr 18 Apr 19 Apr
Activity R0 R0 R0
Fadeouts None expected None expected None expected
10.7cm/SSN 110/60 110/60 108/58
COMMENT: Solar flare activity was at the R0 level during UT day
16-Apr. Solar region AR4419 (N13E31, beta-gamma) has continued
to slowly develop and produced several low level C1 flares in
the past 24 hours and this medium sized region is currently the
largest of the on disk regions. Smaller solar region AR4416 (N19W67,
beta) is decaying as it approaches the northwest solar limb.
Solar region AR4415 (S18W34, alpha) is a stable monopole. There
are currently three numbered regions on the visible solar disk.
A new small solar region may soon rotate onto the solar disk
at solar latitude N13. Solar flare activity is forecast to be
at the R0 level over 17-19 Apr, with a slight chance of an isolated
R1 flare from AR4419. S0 solar radiation storm conditions were
observed on 16-Apr. S0 solar radiation storm conditions are expected
for 17-19 Apr. No Earth directed CMEs have been observed. A westward
CME was observed from 15/2348UT and is considered a far side
event. A large isolated coronal hole is located across the solar
central meridian. The solar wind speed on UT day 16-Apr was light
and steady and ranged from 343 to 319 km/s and is currently at
334 km/s. The peak total interplanetary magnetic field strength
(IMF, Bt) was 7 nT and the north-south IMF component (Bz) ranged
between -4 and +4 nT. A very weak partial shock signature was
observed in some of the solar wind parameters at 16/0254UT. An
increase in the solar wind speed is expected from late 17-Apr
and on 18-Apr from the large coronal hole now crossing the solar
central meridian, with possible moderate southward fluctuations
of the IMF Bz component prior to and during the Earth's entry
into the high speed wind stream.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 16 Apr: G0
Estimated Indices 16 Apr : A K
Australian Region 1 01000011
Cocos Island 1 11100010
Darwin 2 12100012
Townsville 2 12000012
Learmonth 1 11000010
Alice Springs 1 01000011
Gingin 1 01000020
Canberra 1 01000011
Kennaook Cape Grim 0 00000010
Hobart 0 00000010
Estimated Antarctic Regional K Indices 16 Apr :
Macquarie Island 0 00000000
Casey 5 13310020
Mawson 4 02210032
Observed Regional daily pc3 Indices 16 Apr :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 0 (Quiet)
Canberra 2 (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 16 Apr : A
Fredericksburg 4
Planetary 4
Observed AFr/Ap Indices 15 Apr : A K
Fredericksburg 3
Planetary 4 1111 1212
2B. MAGNETIC FORECAST
Date Ap Conditions
17 Apr 18 G0, then G1
18 Apr 30 G1, chance G2
19 Apr 25 G1, chance G2
COMMENT: ASWFC Geomagnetic Warning 28 was issued on 15 April
and is current for 17-19 Apr. G0 geomagnetic conditions were
observed in the Australian and Antarctic regions on UT day 16-Apr.
G0 geomagnetic conditions are expected for most of 17-Apr. A
coronal hole wind stream is expected to increase geomagnetic
activity possibly to G1 from late 17-Apr with G1, chance G2 conditions
expected on 18-19 Apr.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
16 Apr Normal Normal Fair-normal
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
17 Apr Normal Normal-fair Fair
18 Apr Normal Fair Fair-poor
19 Apr Normal Fair Fair-poor
COMMENT: Global HF radio propagation conditions were fair to
normal on 16-Apr. Ionospheric scintillation was observed at Niue
during the interval 16/0833-0848UT. Fair to normal HF conditions
are expected 17-Apr with degraded conditions expected for middle
to high latitudes from 18-Apr due to anticipated geomagnetic
activity from a coronal hole wind stream.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
16 Apr 60
Observed Australian Regional MUFs
Cocos Island Region:
Enhanced by 20% during local day.
Depressed by 35% during local night.
Niue Island Region:
Near predicted monthly values.
Northern Australian Region:
Near predicted monthly values during local day.
Depressed by 30% during local night.
Southern Australian Region:
Depressed by 15% during local day.
Near predicted monthly values during local night.
Antarctic Region (Casey/Davis/Mawson):
Near predicted monthly values over the UT day.
Monthly T index:
Month T index
Mar 92
Apr 83
May 81
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
17 Apr 70 Depressed 10 to 15%/near predicted monthly values
18 Apr 45 Depressed 20 to 30%/near predicted monthly values
19 Apr 30 Depressed 20 to 30%/near predicted monthly values
COMMENT: ASWFC Preliminary HF Communications Warning 36 was issued
on 16 April and is current for 18-20 Apr. Maximum Usable Frequencies
(MUFs) in the Australian region on UT day 16-Apr were depressed
30% to near predicted monthly values. Depressions of up to 30%
were observed during local night hours in the northern Australian
region. The recent ionospheric depressions are not associated
with geomagnetic activity. Southern Australian region MUFs are
expected to be 15% depressed to near predicted monthly values
on 17-Apr. Degraded HF conditions may be experienced for the
southern Australian region from 18-Apr in association with anticipated
geomagnetic activity induced by a coronal hole wind stream.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 15 Apr
Daily Proton Fluence >1 MeV: 5.6E+05
Daily Proton Fluence >10 MeV: 1.8E+04
Daily Electron Fluence >2 MeV: 1.10E+08 (moderate fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability:11%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B3.0
DSCOVR Satellite Solar Wind Day Averaged Data for 15 Apr
Speed: 348 km/sec Density: 3.4 p/cc Temp: 38800 K Bz: 0 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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