[Ips-dsgr] ASWFC Daily Report - 27 April 26 issued 2330 UT on 27 Apr 2026 [SEC=OFFICIAL]

Tue Apr 28 09:30:45 AEST 2026

SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/27 APRIL 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 27 APRIL AND FORECAST FOR 28 APRIL - 30 APRIL
STATUS INDICATORS SOL:** RED **   MAG:GREEN     ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 27 Apr:  R1

Flares    Max     Fadeout    Freq.  Sectors
  M6.0 26/2257UT  probable   lower  East Pacific/
                                    North American
  M1.0    0645UT  possible   lower  Mid East/Indian

Observed 10.7 cm flux/Equivalent Sunspot Number for 27 Apr: 142/96

1B. SOLAR FORECAST
             28 Apr             29 Apr             30 Apr
Activity     R2, chance of R3   R2, chance of R3   R2, chance of R3
Fadeouts     Probable           Probable           Probable
10.7cm/SSN   145/99             145/99             145/99

COMMENT: Solar flare activity reached the R1 level on UT day 
27-Apr, with an M1.0 flare from Active Region (AR) 4425 (N05E38, 
beta-gamma-delta), peaking at 27/0645UT. This region is the largest 
of seven regions on the visible solar disk, and has exhibited 
some growth over the last 24 hours. AR 4424 (N17E06, beta-gamma) 
has also shown some mild growth and spot separation. Region of 
interest, AR 4420 (N16W26, beta-gamma-delta), has shown some 
minor decay. A new unnumbered region appeared at S25E28 and currently 
has a beta magnetic classification. All other regions are either 
stable or in decay. Solar flare activity is forecast to be at 
the R2 level, with a chance of R3 over 28-30 Apr, given the magnetic 
complexity of flare-active regions 4420 and 4425. S0 solar proton 
conditions were recorded throughout UT day 27-Apr, with the solar 
proton flux persisting at background levels. S0 solar proton 
conditions are forecast for 28-30 Apr. No geoeffective coronal 
mass ejections (CMEs) have been observed over the last 24 hours 
in available coronagraph imagery. The solar wind speed was constant 
throughout UT day 27-Apr, broadly ranging between 420 and 460 
km/s. The interplanetary magnetic field strength (IMF, Bt) peaked 
at 6 nT during the UT day, and the north-south component (Bz) 
ranged between -3 and +5 nT over the UT day. The solar wind will 
remain moderate over 28-Apr, before a rise during 29-Apr due 
to the Earth entering a high speed wind stream from a small equatorial 
coronal hole. The wind speed will remain elevated on 30-Apr.

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2A. MAGNETIC SUMMARY

Geomagnetic field for Australian Region 27 Apr: G0

Estimated Indices 27 Apr : A   K           
   Australian Region       4   22112101
      Cocos Island         2   21110100
      Darwin               5   22222111
      Townsville           5   22122112
      Learmonth            6   32222200
      Alice Springs        4   22112101
      Gingin               5   31112210
      Canberra             3   22012101
      Kennaook Cape Grim   4   22112101
      Hobart               3   21112101    

Estimated Antarctic Regional K Indices 27 Apr :
      Macquarie Island     2   21012000
      Casey                9   34321111
      Mawson              16   53222234

Observed Regional daily pc3 Indices 27 Apr : 
      Darwin               0   (Quiet)
      Townsville           0   (Quiet)
      Learmonth            0   (Quiet)
      Alice Springs        0   (Quiet)
      Gingin               2   (Quiet)
      Canberra             6   (Quiet)
      Hobart              16   (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 27 Apr : A 
           Fredericksburg         7
           Planetary              7                         

Observed AFr/Ap Indices 26 Apr :  A   K
           Fredericksburg        13
           Planetary             14   3434 213-     

2B. MAGNETIC FORECAST 
Date      Ap    Conditions
28 Apr     6    G0
29 Apr    14    G0, chance of G1
30 Apr    12    G0

COMMENT: G0 geomagnetic conditions were observed in the Australian 
region, and at the planetary level. An isolated G1 interval was 
observed at Mawson. G0 geomagnetic conditions are forecast for 
28-Apr. G0, with a chance of G1 conditions are forecast for 29-Apr 
due to high speed wind stream effects from a small equatorial 
coronal hole. G0 conditions are forecast for 30-Apr.

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3A. GLOBAL HF PROPAGATION SUMMARY
	            Latitude Band
Date        Low            Middle         High 
27 Apr      Normal         Normal         Normal         

PCA Event : No event.

3B. GLOBAL HF PROPAGATION FORECAST
	            Latitude Band
Date        Low            Middle         High 
28 Apr      Normal         Normal         Normal
29 Apr      Normal         Normal         Normal-fair
30 Apr      Normal         Normal-fair    Normal-fair

COMMENT: Global ionospheric conditions were mostly normal across 
UT day 27-Apr, with no significant degradations observed. Normal 
ionospheric conditions are forecast for the period 28-29 Apr, 
with normal to fair conditions forecast on 30-Apr due to coronal 
hole high speed wind stream effects. Shortwave fadeouts are probable.

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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY

Date   T index
27 Apr    85

Observed Australian Regional MUFs
   Cocos Island Region:
      No data available during local day.
      No data available during local night.
   Niue Island Region:
      Enhanced by 15% during local day.
      Near predicted monthly values during local night.
   Northern Australian Region:
      Near predicted monthly values.
   Southern Australian Region:
      Near predicted monthly values.
   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
28 Apr    80    Near predicted monthly values
29 Apr    80    Near predicted monthly values
30 Apr    80    Near predicted monthly values

COMMENT: ASWFC SWF HF Communications Warning 43 was issued on 
27 April and is current for 27-29 Apr. Maximum Usable Frequencies 
(MUFs) in the Australian and Antarctic regions were near predicted 
monthly values across UT day 27-Apr. Spread-F was observed at 
sites in the Southern Australian region. MUFs are expected to 
remain near predicted values over 28-29 Apr, with some small 
depressions possible on 30-Apr due to forecast geomagnetic activity. 
Shortwave fadeouts are probable.

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5. SPACE ENVIRONMENT SUMMARY

GOES satellite data for 26 Apr
       Daily Proton Fluence >1 MeV:   8.5E+05
       Daily Proton Fluence >10 MeV:  2.0E+04
       Daily Electron Fluence >2 MeV: 2.00E+07   (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 3%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
       X-ray background: C1.0

DSCOVR Satellite Solar Wind Day Averaged Data for 26 Apr
Speed: 458 km/sec  Density:    5.2 p/cc  Temp:   108000 K  Bz:   2 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