[Ips-dhfpr] ASWFC Daily HF Prop Report - 21 December 25 issued 2330 UT on 21 Dec 2025 [SEC=OFFICIAL]

[Australian Space Weather Forecasting Centre]

SUBJ: ASWFC DAILY HF PROPAGATION REPORT
ISSUED AT 2330UT/21 DECEMBER 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECAST CENTRE
AUSTRALIAN REGION SUMMARY AND FORECAST

1. SUMMARY (21 DECEMBER) 
Date   T index  Conditions    
21 Dec   122    Normal-fair    

Flares    Max     Fadeout    Freq.  Sectors
  M1.3    1827UT  possible   lower  East Pacific/
                                    North American

MUFs:
   Cocos Island Region:
      Near predicted monthly values during local day.
      Enhanced by 30% during local night.
   Niue Island Region:
      Depressed by 20% during local day.
      Near predicted monthly values during local night.
   Northern Australian Region:
      Near predicted monthly values during local day.
      Enhanced by 35% during local night.
      Depressed by 25% after local dawn.
   Southern Australian Region:
      Mostly near predicted monthly values.
      Depressed by 20% after local dawn.
   Antarctic Region (Casey/Davis/Mawson):
      Near predicted monthly values over the UT day.

PCA Event : No event.

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


2. FORECAST (22 DECEMBER - 24 DECEMBER)
Date   T index  Conditions       MUFs                              
22 Dec    70    Fair-normal      15 to 20% below predicted monthly 
                                 values
23 Dec    70    Fair-normal      15 to 20% below predicted monthly 
                                 values    
24 Dec    90    Normal-fair      Near predicted monthly values   

COMMENT: Maximum usable frequencies (MUFs) were mostly near predicted 
values during UT day 21-Dec, with some enhancements observed 
during local night hours in the Northern Australian region, and 
20-25% depressions observed during local morning across the northern 
and southern Australian regions. Low frequency sporadic-E was 
observed, particularly in the Brisbane, Townsville, and Perth 
regions. Spread F was also observed in Hobart during local night 
hours. MUFs are forecast to be 15-20% depressed on 22-23 Dec 
due to ongoing high-speed wind stream effects from an equatorial 
coronal hole. These conditions are expected to improve towards 
monthly predicted values over 24-Dec as high speed wind stream 
effects subside. Sporadic-E during local night hours may also 
be observed. 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