[Ips-dsgr] ASWFC Daily Report - 18 May 26 issued 2330 UT on 18 May 2026 [SEC=OFFICIAL]

Tue May 19 09:30:44 AEST 2026

SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/18 MAY 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 18 MAY AND FORECAST FOR 19 MAY - 21 MAY
STATUS INDICATORS SOL:GREEN   MAG:GREEN     ION: ** YELLOW **
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 18 May:  R0

Flares: none.

Observed 10.7 cm flux/Equivalent Sunspot Number for 18 May: 105/54

1B. SOLAR FORECAST
             19 May             20 May             21 May
Activity     R0, chance of R1   R0, chance of R1   R0, chance of R1
Fadeouts     None expected      None expected      None expected
10.7cm/SSN   110/60             115/66             115/66

COMMENT: Solar flare activity on UT day 18-May was at the R0 
level, with no significant flaring activity. There are currently 
six numbered sunspot regions visible on the solar disk. Active 
Region (AR) 4441 (N08E04, beta) is the largest region on the 
disk and has shown recent development in its intermediate spots. 
All other sunspot regions are either stable or in decay. Solar 
flare activity is expected to be at the R0 level over 19-21 May, 
with a chance of R1. S0 solar proton conditions were observed 
on UT day 18-May. S0 solar proton conditions are expected over 
19-21 May. No Earth-directed coronal mass ejections (CMEs) have 
been observed. The solar wind speed on UT day 18-May mildly declined, 
ranging from 570 to 520 km/s and is currently near 520 km/s. 
The peak total interplanetary magnetic field strength (IMF, Bt) 
was 5 nT and the north-south IMF component (Bz) range was -5 
to +4 nT. The solar wind speed is expected to decrease over 19-21 
May.

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2A. MAGNETIC SUMMARY

Geomagnetic field for Australian Region 18 May: G0

Estimated Indices 18 May : A   K           
   Australian Region       7   22223212
      Cocos Island         5   12122212
      Darwin               6   22222212
      Townsville           7   22123212
      Learmonth            9   22223322
      Alice Springs        5   12122212
      Gingin              10   22233322
      Canberra             6   21132212
      Kennaook Cape Grim   8   21233222
      Hobart               8   21233212    

Estimated Antarctic Regional K Indices 18 May :
      Macquarie Island    18   21255412
      Casey               13   33333223
      Mawson              34   44633246

Observed Regional daily pc3 Indices 18 May : 
      Darwin               0   (Quiet)
      Townsville           0   (Quiet)
      Learmonth            0   (Quiet)
      Alice Springs        0   (Quiet)
      Gingin              19   (Quiet)
      Canberra            39   (Quiet to unsettled)
      Hobart              55   (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 18 May : A 
           Fredericksburg        11
           Planetary             15                         

Observed AFr/Ap Indices 17 May :  A   K
           Fredericksburg         7
           Planetary              8   2222 2222     

2B. MAGNETIC FORECAST 
Date      Ap    Conditions
19 May    12    G0
20 May    10    G0
21 May     8    G0

COMMENT: ASWFC Geomagnetic Warning 33 was issued on 17 May and 
is current for 18-19 May. G0 geomagnetic conditions were observed 
in the planetary and Australian regions on UT day 18-May. G2 
geomagnetic conditions were observed in the Antarctic region. 
G0 planetary geomagnetic conditions are expected over 19-21 May.

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

PCA Event : No event.

3B. GLOBAL HF PROPAGATION FORECAST
	            Latitude Band
Date        Low            Middle         High 
19 May      Normal         Normal         Normal-fair
20 May      Normal         Normal         Normal-fair
21 May      Normal         Normal         Normal-fair

COMMENT: Global ionospheric conditions were mostly fair over 
UT day 18-May, with most degradations observed in southern hemisphere 
regions. Mostly normal HF propagation conditions are expected 
over 19-21 May.

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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY

Date   T index
18 May    39

Observed Australian Regional MUFs
   Cocos Island Region:
      No data available during local day.
      No data available during local night.
   Niue Island Region:
      Depressed by 20% during local day.
      Depressed by 30% during local night.
   Northern Australian Region:
      Near predicted monthly values during local day.
      Depressed by 25% during local night.
   Southern Australian Region:
      Depressed by 15% during local day.
      Depressed by 30% during local night.
   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
19 May    40    15 to 20% below predicted monthly values
20 May    55    Near predicted monthly values
21 May    65    Near predicted monthly values

COMMENT: ASWFC HF Communications Warning 49 was issued on 18 
May and is current for 18-19 May. Maximum Usable Frequencies 
(MUFs) were near predicted monthly values in the northern Australian 
region during local day, but depressed by 25% during local night. 
MUFs were depressed by 15-30% in southern Australia over the 
UT day. Spread-F was observed at Hobart and Canberra during local 
night hours. MUFs are expected to be 15-20% depressed on 19-May, 
recovering to near predicted monthly values over 20-21 May.

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5. SPACE ENVIRONMENT SUMMARY

GOES satellite data for 17 May
       Daily Proton Fluence >1 MeV:   4.4E+06
       Daily Proton Fluence >10 MeV:  2.1E+04
       Daily Electron Fluence >2 MeV: 2.90E+08   (moderate fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability:18%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
       X-ray background: B4.7

DSCOVR Satellite Solar Wind Day Averaged Data for 17 May
Speed: 625 km/sec  Density:    1.6 p/cc  Temp:   175000 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