[Ips-dsgr] ASWFC Daily Report - 19 April 26 issued 2330 UT on 19 Apr 2026 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Mon Apr 20 09:30:46 AEST 2026
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/19 APRIL 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 19 APRIL AND FORECAST FOR 20 APRIL - 22 APRIL
STATUS INDICATORS SOL:GREEN MAG:** YELLOW ** ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 19 Apr: R0
Flares: none.
Observed 10.7 cm flux/Equivalent Sunspot Number for 19 Apr: 105/54
1B. SOLAR FORECAST
20 Apr 21 Apr 22 Apr
Activity R0 R0 R0
Fadeouts None expected None expected None expected
10.7cm/SSN 105/54 110/60 120/72
COMMENT: Solar flare activity on UT day 19-Apr was at the R0
level, with no C-class or greater flares observed over the past
24 hours. There are currently two Active Regions (ARs) on the
visible solar disk, with AR 4419 (N15W11, beta) being the largest
and most magnetically complex. Both this region and AR 4415 (S18W76,
alpha) have remained stable throughout UT day 19-Apr. Solar flare
activity is forecast to remain at the R0 level over 20-22 Apr.
S0 solar proton conditions were observed throughout the past
UT day, with solar proton flux remaining at background levels.
S0 solar proton conditions are expected over 20-22 Apr. No coronal
mass ejections were observed in the past 24 hours in available
coronagraph imagery. The solar wind speed was elevated on 19-Apr
due to a coronal hole high speed wind stream. The solar wind
speed was broadly constant, broadly ranging between 450 and 520
km/s across the UT day. The interplanetary magnetic field strength
(IMF, Bt) peaked early in the UT day, reaching 12 nT, before
declining over the course of the UT day. The north-south component
(Bz) ranged between -7 and +9 nT over this time. An extended
period of southward Bz was observed between 19/0410-0550UT. The
solar wind speed is expected to slowly decline over 20-22 Apr,
as the coronal hole high speed wind stream moves past its geoeffective
position.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 19 Apr: G2
Estimated Indices 19 Apr : A K
Australian Region 12 33432320
Cocos Island 6 22312210
Darwin 12 33432221
Townsville 12 33432221
Learmonth 13 33432321
Alice Springs 11 33432220
Gingin 12 32343320
Canberra 15 33532320
Kennaook Cape Grim 18 24543320
Hobart 15 34442320
Estimated Antarctic Regional K Indices 19 Apr :
Macquarie Island 28 34564330
Casey 14 43332411
Mawson 60 55743656
Observed Regional daily pc3 Indices 19 Apr :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 21 (Quiet to unsettled)
Canberra 38 (Quiet to unsettled)
Hobart 24 (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 19 Apr : A
Fredericksburg 18
Planetary 26
Observed AFr/Ap Indices 18 Apr : A K
Fredericksburg 24
Planetary 33 ---- ----
2B. MAGNETIC FORECAST
Date Ap Conditions
20 Apr 20 G0, chance of G1
21 Apr 15 G0
22 Apr 12 G0
COMMENT: Geomagnetic conditions in the Australian region were
at the G0 level throughout 19-Apr. A G1 interval was observed
at Cape Grim. G2 geomagnetic conditions were reported at the
planetary level, with an isolated G3 interval reported in the
Antarctic region at Mawson. These geomagnetic conditions are
due to an ongoing coronal hole high speed wind stream. The effects
of this wind stream are expected to wane, with G0 geomagnetic
conditions, with a chance of G1, are forecast for 20-Apr. This
will decline further to G0 conditions over 21-22 Apr as this
high speed wind stream moves past a geoeffective position.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
19 Apr Poor Poor Poor
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
20 Apr Fair-poor Fair-poor Fair-poor
21 Apr Normal-fair Normal-fair Fair
22 Apr Normal Normal Normal-fair
COMMENT: Global ionospheric conditions on UT day 19-Apr were
poor, with widespread degradations observed at all latitudes
due to ongoing geomagnetic activity. Conditions are expected
to slowly recover over 20-22 Apr, with fair conditions on 20-Apr
improving towards normal-fair conditions on 21-Apr, and normal
conditions by 22-Apr.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
19 Apr 71
Observed Australian Regional MUFs
Cocos Island Region:
Near predicted monthly values during local day.
Depressed by 35% during local night.
Niue Island Region:
Mostly near predicted monthly values.
Depressed by 25% after local dawn.
Northern Australian Region:
Near predicted monthly values during local day.
Depressed by 35% during local night.
Southern Australian Region:
Near predicted monthly values during local day.
Depressed by 15% during local night.
Depressed by 20% after local dawn.
Antarctic Region (Casey/Davis/Mawson):
Depressed by 25% 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
20 Apr 65 Depressed 15 to 20%/near predicted monthly values
21 Apr 75 Near predicted monthly values
22 Apr 80 Near predicted monthly values
COMMENT: ASWFC HF Communications Warning 37 was issued on 19
April and is current for 19-20 Apr. Maximum Usable Frequencies
(MUFs) in the Australian region on UT day 19-Apr were initially
near predicted monthly values, but became depressed over the
UT day due to ongoing geomagnetic activity. Depressions of up
to 35% were recorded across the Northern Australian region and
at the Cocos Islands during local night and dawn hours. Depressions
of 20-25% were also reported across the Southern Australian region,
as well as the Antarctic region and Niue Island. Strong spread-F
was present in the southern Australian region, and sporadic-E
was recorded at Canberra and Norfolk Island. MUFs are expected
to remain depressed by 15-20% for UT day 20-Apr due to the ongoing
geomagnetic activity, before trending towards predicted monthly
values over 21-22 Apr.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 18 Apr
Daily Proton Fluence >1 MeV: 1.8E+06
Daily Proton Fluence >10 MeV: 1.7E+04
Daily Electron Fluence >2 MeV: 1.10E+07 (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 2%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: B3.0
DSCOVR Satellite Solar Wind Day Averaged Data for 18 Apr
Speed: 490 km/sec Density: 5.4 p/cc Temp: 190000 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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