[Ips-dsgr] ASWFC Daily Report - 27 December 25 issued 2330 UT on 27 Dec 2025 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Sun Dec 28 10:30:52 AEDT 2025
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/27 DECEMBER 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 27 DECEMBER AND FORECAST FOR 28 DECEMBER - 30 DECEMBER
STATUS INDICATORS SOL:** YELLOW ** MAG:** YELLOW ** ION: GREEN
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 27 Dec: R2
Flares Max Fadeout Freq. Sectors
M5.1 0150UT confirmed lower West Pacific
Observed 10.7 cm flux/Equivalent Sunspot Number for 27 Dec: 178/131
1B. SOLAR FORECAST
28 Dec 29 Dec 30 Dec
Activity R1,chance R2 R1,chance R2 R1,chance R2
Fadeouts Possible Possible Possible
10.7cm/SSN 175/129 170/124 160/114
COMMENT: Solar activity on UT day 27-Dec was R2 due to a short
duration M5.1 flare from AR4325 (S09E60, beta). This region flared
as it emerged on the disk, with the region consisting of a number
of small spots and the region is currently slowly growing. Magnetic
classification is difficult due to limb foreshortening and the
size of the spots. Solar region AR4321 (S11W46, beta) shows an
increasing penumbral area and some redevelopment/redistribution
in its small umbras and produced a single low level C class flare.
Region AR4324 (N26E66, beta) shows slight growth in intermediate
penumbral area and intermediate spots and produced several low
to mid level C class flares. In GONG H-alpha imagery a parallel
ribbon optical flare was observed from 27/2231UT at N12W12 located
between decayed region AR4318 (N06W08, -) and region AR4317 (N11W17,
beta). The optical flare was associated with a C9.8 X-ray flare
at 27/2233UT. There are currently eight numbered sunspot regions
on the solar disk. All other sunspot regions are small and either
stable or in decay. Solar activity is expected to be R1, chance
R2 over 28-30 Dec. S0 solar radiation storm conditions were observed
on UT day 27-Dec. S0 solar radiation storm conditions are expected
over 28-30 Dec. No Earth directed CMEs were observed on UT day
27-Dec. A very slow east directed CME was observed from 27/0224UT
following the M5.1 flare. The CME was modelled as an Earth miss.
The solar wind speed on UT day 27-Dec was moderate and declined
as the influence of a coronal hole slowly abates. The solar wind
speed ranged from 527 to 451 km/s and is currently at 460 km/s.
The peak total interplanetary field strength (IMF, Bt) was 6
nT and the north-south IMF component range was +4 to -5 nT. The
solar wind is expected to continue to gradually decline over
28-30 Dec before increasing on 31-Dec due to a wind stream from
an isolated coronal hole in the northeast solar quadrant that
has started to cross the solar central meridian. This hole is
smaller and less distinct on this solar rotation. On the last
two solar rotations a period of southward IMF conditions preceded
the entry into the coronal hole's wind stream, implying southward
IMF conditions are possible on 30-Dec.
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2A. MAGNETIC SUMMARY
Geomagnetic field for Australian Region 27 Dec: G0
Estimated Indices 27 Dec : A K
Australian Region 5 22211122
Cocos Island 3 12110121
Darwin 6 22211123
Townsville 8 32312122
Learmonth 7 32212122
Alice Springs 5 22211122
Gingin 6 22211132
Canberra 6 23221112
Kennaook Cape Grim 7 23222122
Hobart 7 23222112
Estimated Antarctic Regional K Indices 27 Dec :
Macquarie Island 5 12132012
Casey 30 46632233
Mawson 18 34332253
Observed Regional daily pc3 Indices 27 Dec :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 2 (Quiet)
Canberra 6 (Quiet)
Hobart 18 (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 Dec : A
Fredericksburg 7
Planetary 7
Observed AFr/Ap Indices 26 Dec : A K
Fredericksburg 6
Planetary 8 2222 2311
2B. MAGNETIC FORECAST
Date Ap Conditions
28 Dec 6 G0
29 Dec 6 G0
30 Dec 20 G1, chance G2
COMMENT: ASWFC Geomagnetic Warning 102 was issued on 27 December
and is current for 30-31 Dec. G0 geomagnetic conditions were
observed in the Australian region on UT day 27-Dec. G0-G2 geomagnetic
conditions were observed in the Antarctic region. G0 geomagnetic
conditions are expected over 28-29 Dec. For 30-Dec planetary
geomagnetic 27-day recurrence patterns show G3 conditions for
the last two rotations due to southward IMF conditions preceding
a coronal hole wind stream entry. However, the coronal hole on
this rotation is smaller and less distinct possibly indicating
the southward IMF structure in the solar wind may also be weaker.
Planetary G1, chance G2 conditions are forecast for 30-Dec. Geomagnetic
activity in the Australian region is expected to be G0, chance
G1 on 30-31 Dec.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
27 Dec Normal Normal Fair-normal
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
28 Dec Normal Normal Normal-fair
29 Dec Normal Normal Normal-fair
30 Dec Normal Normal-fair Fair
COMMENT: HF radio propagation conditions on UT day 27-Dec were
normal. HF radio propagation conditions are expected to be normal
over 28-29 Dec, becoming fair on 30-31 Dec due to anticipated
geomagnetic activity preceding entry into a coronal hole wind
stream. Isolated shortwave fadeouts are possible.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
27 Dec 124
Observed Australian Regional MUFs
Cocos Island Region:
No data.
Niue Island Region:
Near predicted monthly values.
Northern Australian Region:
Near predicted monthly values during local day.
Enhanced by 30% during local night.
Southern Australian Region:
Near predicted monthly values during local day.
Enhanced by 20% during local night.
Antarctic Region (Casey/Davis/Mawson):
Near predicted monthly values over the UT day.
Monthly T index:
Month T index
Nov 103
Dec 89
Jan 89
4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
Date T index MUFs
28 Dec 115 Near predicted monthly values to 15% enhanced
29 Dec 115 Near predicted monthly values to 15% enhanced
30 Dec 115 Near predicted monthly values to 15% enhanced
COMMENT: ASWFC SWF HF Communications Warning 124 was issued on
27 December and is current for 27-29 Dec. Maximum usable frequencies
(MUFs) in the Australian region on UT day 27-Dec were near predicted
values to 30% enhanced. Sporadic was observed at times at some
sites. A shortwave fadeout was observed 27/0143-0226UT. MUFs
are expected to be near predicted values to 15% enhanced over
28-30 Dec. HF conditions for the southern Australian region may
become degraded during local night hours on 30-Dec, with mild
depressions possible on 31-Dec. Isolated shortwave fadeouts are
possible.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 26 Dec
Daily Proton Fluence >1 MeV: 1.8E+06
Daily Proton Fluence >10 MeV: 1.7E+04
Daily Electron Fluence >2 MeV: 3.10E+08 (moderate fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability:19%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: C1.4
DSCOVR Satellite Solar Wind Day Averaged Data for 26 Dec
Speed: 525 km/sec Density: 1.9 p/cc Temp: 118000 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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