[Ips-dhfpr] ASWFC Daily HF Prop Report - 12 December 25 issued 2330 UT on 12 Dec 2025 [SEC=OFFICIAL]

[Australian Space Weather Forecasting Centre]

SUBJ: ASWFC DAILY HF PROPAGATION REPORT
ISSUED AT 2330UT/12 DECEMBER 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECAST CENTRE
AUSTRALIAN REGION SUMMARY AND FORECAST

1. SUMMARY (12 DECEMBER) 
Date   T index  Conditions    
12 Dec    81    Fair           

Flares    Max     Fadeout    Freq.  Sectors
  M2.0    0505UT  possible   lower  E. Asia/Aust.

MUFs:
   Cocos Island Region:
      Mostly near predicted monthly values.
   Niue Island Region:
      Near predicted monthly values during local day.
      Enhanced by 30% during local night.
   Northern Australian Region:
      Enhanced by 15% during local day.
      Near predicted monthly values during local night.
      Depressed by 35% after local dawn.
   Southern Australian Region:
      Depressed by 15% during local day.
      Near predicted monthly values during local night.
      Depressed by 35% after local dawn.
   Antarctic Region (Casey/Davis/Mawson):
      Depressed by 15% over the UT day.

PCA Event : No event.

Monthly T index:
Month  T index
Nov      103
Dec      89
Jan      89


2. FORECAST (13 DECEMBER - 15 DECEMBER)
Date   T index  Conditions       MUFs                              
13 Dec    65    Fair             Depressed 15 to 20%/near predicted 
                                 monthly values
14 Dec    70    Normal-fair      Depressed 10 to 15%/near predicted 
                                 monthly values    
15 Dec    85    Normal           Near predicted monthly values   

COMMENT: ASWFC HF Communications Warning 121 was issued on 12 
December and is current for 13 Dec only. Maximum usable frequencies 
(MUFs) in the Australian region on UT day 12-Dec were 35% depressed 
to 15% enhanced, with depressed conditions observed in the southern 
Australian region. Spread F was observed at Hobart during local 
night hours. MUFs in the southern Australian region are 15-35% 
depressed after local dawn this morning. MUFs are expected to 
be range from 20% depressed to near predicted monthly values 
over 13-15 Dec, with mildly degraded HF conditions during local 
night hours due to anticipated geomagnetic activity induced by 
a coronal hole wind stream. A minor HF fadeout impacting lower 
HF frequencies was observed 12/0459-0516UT. Isolated minor shortwave 
fadeouts are possible.

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For an explanation of some of the terms in this report, go to
https://www.sws.bom.gov.au, and follow links to Educational->
Glossary on Solar Terrestrial Terms.

Australian Space Weather Forecasting Centre
Bureau of Meteorology
ASWFC at bom.gov.au
www.bom.gov.au | www.sws.bom.gov.au