[Ips-dhfpr] ASWFC Daily HF Prop Report - 20 December 25 issued 2330 UT on 20 Dec 2025 [SEC=OFFICIAL]

[Australian Space Weather Forecasting Centre]

SUBJ: ASWFC DAILY HF PROPAGATION REPORT
ISSUED AT 2330UT/20 DECEMBER 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECAST CENTRE
AUSTRALIAN REGION SUMMARY AND FORECAST

1. SUMMARY (20 DECEMBER) 
Date   T index  Conditions    
20 Dec    99    Normal         

Flares    Max     Fadeout    Freq.  Sectors
  M1.0    0753UT  possible   lower  Mid East/Indian

MUFs:
   Cocos Island Region:
      Near predicted monthly values.
   Niue Island Region:
      Near predicted monthly values.
   Northern Australian Region:
      Near predicted monthly values.
   Southern Australian Region:
      Near predicted monthly values.
   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 (21 DECEMBER - 23 DECEMBER)
Date   T index  Conditions       MUFs                              
21 Dec    95    Normal           Near predicted monthly values
22 Dec    70    Fair             Depressed 10 to 15%/near predicted 
                                 monthly values    
23 Dec    70    Fair             Depressed 10 to 15%/near predicted 
                                 monthly values   

COMMENT: Maximum usable frequencies (MUFs) were largely near 
predicted values across the entire Australian region during UT 
day 20-Dec. Low frequency sporadic-E was observed during local 
night hours, particularly in Brisbane. MUFs are forecast to be 
near monthly predicted values throughout 21 Dec, declining to 
10–15% below predicted values on 22-23 Dec as high-speed wind 
stream effects from an equatorial coronal hole commence. Sporadic-E 
during local night hours may also be observed. 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