[Ips-dsgr] ASWFC Daily Report - 21 May 26 issued 2330 UT on 21 May 2026 [SEC=OFFICIAL]

Fri May 22 09:30:48 AEST 2026

SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/21 MAY 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 21 MAY AND FORECAST FOR 22 MAY - 24 MAY
STATUS INDICATORS SOL:** YELLOW **   MAG:GREEN     ION: ** YELLOW **
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 21 May:  R0

Flares: none.

Observed 10.7 cm flux/Equivalent Sunspot Number for 21 May: 118/70

1B. SOLAR FORECAST
             22 May             23 May             24 May
Activity     R0, chance of R1   R0, chance of R1   R0, chance of R1
Fadeouts     Possible           Possible           Possible
10.7cm/SSN   120/72             120/72             125/78

COMMENT: Solar flare activity on UT day 21-May was at the R0 
level, with a C9.5 flare observed at 21/1825UT. There are currently 
four numbered sunspot regions visible on the solar disk. AR4436 
(N20W89, beta) was responsible for the largest flare of the UT 
day but has rotated off the solar disk over the UT day. AR4441 
(N08W39, beta-gamma) and AR4443 (S16E10, beta) showed some spot 
development over the UT day, AR4441 is the largest and most magnetically 
complex. All other sunspot regions are either stable or in decay. 
Solar flare activity is expected to be at the R0 level over 22-24 
May, with a chance of R1. S0 solar radiation conditions were 
observed on UT day 21-May. S0 solar radiation conditions are 
expected over 22-24 May. No Earth-directed coronal mass ejections 
(CMEs) were observed on 21-May. The solar wind speed decreased 
over 21-May. The speed ranged from 380 to 480 km/s and is currently 
near 410 km/s. The peak total interplanetary magnetic field strength 
(IMF, Bt) was 5 nT and the north-south IMF component (Bz) range 
was -4 to +4 nT. The solar wind speed is expected to continue 
to decline towards background levels and remain there over 22-24 
May.

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2A. MAGNETIC SUMMARY

Geomagnetic field for Australian Region 21 May: G0

Estimated Indices 21 May : A   K           
   Australian Region       6   22203121
      Cocos Island         2   21101010
      Darwin               6   22212221
      Townsville           6   22203122
      Learmonth            6   22213121
      Alice Springs        5   22202121
      Gingin               7   21213231
      Canberra             4   12103111
      Kennaook Cape Grim   5   12103121
      Hobart               4   12103111    

Estimated Antarctic Regional K Indices 21 May :
      Macquarie Island     3   11013000
      Casey               11   33323222
      Mawson              20   44322254

Observed Regional daily pc3 Indices 21 May : 
      Darwin               0   (Quiet)
      Townsville           0   (Quiet)
      Learmonth            0   (Quiet)
      Alice Springs        0   (Quiet)
      Gingin               0   (Quiet)
      Canberra             6   (Quiet)
      Hobart              11   (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 21 May : A 
           Fredericksburg         7
           Planetary              8                         

Observed AFr/Ap Indices 20 May :  A   K
           Fredericksburg         8
           Planetary              8   3321 2112  

2B. MAGNETIC FORECAST 
Date      Ap    Conditions
22 May     6    G0
23 May     5    G0
24 May     4    G0

COMMENT: G0 geomagnetic conditions were observed in the Australian 
region on UT day 21-May. Mostly G0 geomagnetic conditions were 
observed in the Antarctic region, with G1 conditions observed 
briefly at Mawson. G0 geomagnetic conditions are expected over 
22-24 May.

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3A. GLOBAL HF PROPAGATION SUMMARY
	            Latitude Band
Date        Low            Middle         High 
21 May      Normal         Normal         Normal-fair    

PCA Event : No event.

3B. GLOBAL HF PROPAGATION FORECAST
	            Latitude Band
Date        Low            Middle         High 
22 May      Normal         Normal         Normal
23 May      Normal         Normal         Normal
24 May      Normal         Normal         Normal

COMMENT: Global ionospheric conditions were fair to normal over 
UT day 20-May, with degradations mostly observed in the northern 
hemisphere in the first third of the UT day. Mostly normal HF 
propagation conditions are expected over 22-24 May.

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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY

Date   T index
21 May    50

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 35% during local night.
   Northern Australian Region:
      Near predicted monthly values during local day.
      Depressed by 20% during local night.
   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
Apr      74
May      71
Jun      68

4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date   T index  MUFs
22 May    50    Depressed 15%/near predicted monthly values
23 May    50    Depressed 15%/near predicted monthly values
24 May    50    Depressed 15%/near predicted monthly values

COMMENT: Maximum Usable Frequencies (MUFs) on UT day were depressed 
by up to 20% during local night hours in the northern Australian 
region MUFs were near predicted monthly values in the southern 
Australian region. Spread-F was observed at Hobart and Canberra 
during local night hours. MUFs are expected to be near predicted 
monthly values to depressed by up to 15% over 22-24 May.

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5. SPACE ENVIRONMENT SUMMARY

GOES satellite data for 20 May
       Daily Proton Fluence >1 MeV:   5.0E+05
       Daily Proton Fluence >10 MeV:  1.9E+04
       Daily Electron Fluence >2 MeV: 7.80E+07   (normal fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability: 9%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
       X-ray background: B4.9

DSCOVR Satellite Solar Wind Day Averaged Data for 20 May
Speed: 475 km/sec  Density:    1.1 p/cc  Temp:    83200 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