[Ips-dsgr] ASWFC Daily Report - 28 December 25 issued 2330 UT on 28 Dec 2025 [SEC=OFFICIAL]
Australian Space Weather Forecasting Centre
aswfc at bom.gov.au
Mon Dec 29 10:30:51 AEDT 2025
SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/28 DECEMBER 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE
SUMMARY FOR 28 DECEMBER AND FORECAST FOR 29 DECEMBER - 31 DECEMBER
STATUS INDICATORS SOL:** YELLOW ** MAG:** YELLOW ** ION: ** YELLOW **
ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx
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1A. SOLAR SUMMARY
Activity 28 Dec: R1
Flares Max Fadeout Freq. Sectors
M1.3 2113UT possible lower East Pacific/
North American
M4.2 2239UT possible lower East Pacific/
North American
Observed 10.7 cm flux/Equivalent Sunspot Number for 28 Dec: 188/141
1B. SOLAR FORECAST
29 Dec 30 Dec 31 Dec
Activity R1,chance R2 R1,chance R2 R1,chance R2
Fadeouts Possible Possible Possible
10.7cm/SSN 185/138 175/129 170/124
COMMENT: Solar activity on UT day 28-Dec was R1 due to an M4.2
flare located at N07W26 to the southeast of the leader spot of
AR4317 (N11W30, beta). Yesterday's C9/parallel ribbon flare was
from the same location. This flare also has the same parallel
ribbon structure either side of a neutral line at this location.
An M1.3 flare was produced by solar region AR4325 (S09E48, beta-gamma)
which has grown in size and increased in magnetic complexity.
AR4324 (N26E54, beta-gamma) is showing decay in its intermediate
penumbral area. AR4321 (S11W59, beta-delta) continues to show
overall decay with a reduction in umbral area and AR4317 also
continues to slowly decay with separation of its leader spot.
AR4324 produced several low level C flares. There are currently
ten 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 29-31 Dec primarily due
to AR4325. S0 solar radiation storm conditions were observed
on UT day 28-Dec. S0, chance S1 solar radiation storm conditions
are expected over 29-Dec due to the M4.2 parallel ribbon flare.
S0 conditions are expected for 30-31 Dec. No Earth directed CMEs
were observed on UT day 28-Dec. Yesterday's C9/parallel ribbon
flare did not have an associated CME. Early in the UT day slow
coronal expansion was in progress to the northeast possibly due
to an unstable coronal streamer. Space based coronagraph imagery
will be checked for any CME following the M4.2 flare. An isolated
coronal hole is across the solar central meridian in the northern
solar hemisphere. The solar wind speed on UT day 28-Dec was moderate
and steady possibly sustained by a wind stream from a south polar
extension coronal hole now at solar longitude W40. The solar
wind speed ranged from 503 to 446 km/s and is currently at 453
km/s. The peak total interplanetary field strength (IMF, Bt)
was 7 nT and the north-south IMF component range was +5 to -6
nT. The solar wind speed is expected to gradually decline on
29-30 Dec before increasing on 31-Dec to 600-700km/s due to the
wind stream from the isolated coronal hole in the northern solar
hemisphere. 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 28 Dec: G0
Estimated Indices 28 Dec : A K
Australian Region 7 22122312
Cocos Island 5 22122211
Darwin 8 31122313
Townsville 7 21122322
Learmonth 9 32132312
Alice Springs 6 21122312
Gingin 9 32132322
Canberra 7 22222312
Kennaook Cape Grim 7 22222312
Hobart 7 22222312
Estimated Antarctic Regional K Indices 28 Dec :
Macquarie Island 10 22133411
Casey 26 56433223
Mawson 26 33344355
Observed Regional daily pc3 Indices 28 Dec :
Darwin 0 (Quiet)
Townsville 0 (Quiet)
Learmonth 0 (Quiet)
Alice Springs 0 (Quiet)
Gingin 0 (Quiet)
Canberra 2 (Quiet)
Hobart 10 (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 28 Dec : A
Fredericksburg 6
Planetary 7
Observed AFr/Ap Indices 27 Dec : A K
Fredericksburg 5
Planetary 7 1322 2122
2B. MAGNETIC FORECAST
Date Ap Conditions
29 Dec 6 G0
30 Dec 20 G1, chance G2
31 Dec 18 G0-G1
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 on 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 the Earth's
entry into a coronal hole wind stream which is expected on 31-Dec.
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 and G0-G1 conditions for 31-Dec. Geomagnetic
activity in the Australian region is expected to be G0, chance
G1 over 30-31 Dec.
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3A. GLOBAL HF PROPAGATION SUMMARY
Latitude Band
Date Low Middle High
28 Dec Normal Normal Normal
PCA Event : No event.
3B. GLOBAL HF PROPAGATION FORECAST
Latitude Band
Date Low Middle High
29 Dec Normal Normal Normal
30 Dec Normal Fair-normal Fair
31 Dec Normal Fair-normal Fair
COMMENT: HF radio propagation conditions on UT day 28-Dec were
normal. HF radio propagation conditions are expected to be normal
on 29-Dec, becoming fair on 30-31 Dec due to anticipated geomagnetic
activity preceding the Earth's entry into a coronal hole wind
stream. Isolated shortwave fadeouts are possible.
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4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
Date T index
28 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 20% during local night.
Southern Australian Region:
Near predicted monthly values during local day.
Enhanced by 15% 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
29 Dec 115 Near predicted monthly values to 15% enhanced
30 Dec 115 Near predicted monthly values to 15% enhanced
31 Dec 60 Depressed 15 to 20%/near predicted monthly values
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 28-Dec were near predicted
monthly values to 20% enhanced. MUFs are expected to be near
predicted monthly values to 15% enhanced over 29-30 Dec. HF conditions
for the southern Australian region may become degraded during
local night hours on 30-Dec, with 15-20% depressions possible
on 31-Dec. Isolated shortwave fadeouts are possible.
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5. SPACE ENVIRONMENT SUMMARY
GOES satellite data for 27 Dec
Daily Proton Fluence >1 MeV: 2.0E+06
Daily Proton Fluence >10 MeV: 1.7E+04
Daily Electron Fluence >2 MeV: 2.80E+08 (moderate fluence)
Electron Fluence Daily Deep Dielectric Discharge Probability:18%
Fluence (flux accumulation over 24hrs)/ cm2-ster-day.
X-ray background: C1.7
DSCOVR Satellite Solar Wind Day Averaged Data for 27 Dec
Speed: 486 km/sec Density: 2.1 p/cc Temp: 101000 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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