[Ips-dhfpr] ASWFC Daily HF Prop Report - 19 December 25 issued 2330 UT on 19 Dec 2025 [SEC=OFFICIAL]

[Australian Space Weather Forecasting Centre]

SUBJ: ASWFC DAILY HF PROPAGATION REPORT
ISSUED AT 2330UT/19 DECEMBER 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECAST CENTRE
AUSTRALIAN REGION SUMMARY AND FORECAST

1. SUMMARY (19 DECEMBER) 
Date   T index  Conditions    
19 Dec    91    Normal-fair    

Flares: none.

MUFs:
   Cocos Island Region:
      Depressed by 40% during local day.
      Depressed by 20% during local night.
   Niue Island Region:
      Mostly near predicted monthly values.
      Enhanced by 20% after local dawn.
   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 (20 DECEMBER - 22 DECEMBER)
Date   T index  Conditions       MUFs                              
20 Dec    95    Normal           Near predicted monthly values
21 Dec    90    Normal           Near predicted monthly values    
22 Dec    75    Fair-normal      About 10-15% below predicted 
                                 monthly values   

COMMENT: Maximum usable frequencies (MUFs) were largely near 
predicted values during UT day 19-Dec, with the exception of 
the Cocos Islands, where depressions of 20-40% were observed. 
Low frequency sporadic-E was observed, with spread F also observed 
in the southern Australian region during local night hours. MUFs 
are forecast to be near monthly predicted values throughout 20-21 
Dec, declining to be 10-15% depressed on 22-Dec as high-speed 
wind stream effects from an equatorial coronal hole commence. 
Sporadic-E during local night hours may also be observed.

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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