[Ips-dhfpr] ASWFC Daily HF Prop Report - 18 December 25 issued 2330 UT on 18 Dec 2025 [SEC=OFFICIAL]

[Australian Space Weather Forecasting Centre]

SUBJ: ASWFC DAILY HF PROPAGATION REPORT
ISSUED AT 2330UT/18 DECEMBER 2025
FROM THE AUSTRALIAN SPACE WEATHER FORECAST CENTRE
AUSTRALIAN REGION SUMMARY AND FORECAST

1. SUMMARY (18 DECEMBER) 
Date   T index  Conditions    
18 Dec    96    Fair-normal    

Flares: none.

MUFs:
   Cocos Island Region:
      Mostly near predicted monthly values.
   Niue Island Region:
      Mostly near predicted monthly values.
   Northern Australian Region:
      Near predicted monthly values during local day.
      Enhanced by 15% during local night.
      15% depressed after local dawn.
   Southern Australian Region:
      Depressed 15% early in the UT day then
      near predicted monthly values.
      15% depressed 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 (19 DECEMBER - 21 DECEMBER)
Date   T index  Conditions       MUFs                              
19 Dec    75    Normal           Depressed 10 to 15%/near predicted 
                                 monthly values
20 Dec    85    Normal           Near predicted monthly values    
21 Dec    85    Normal           Near predicted monthly values   

COMMENT: Maximum usable frequencies (MUFs) in the Australian 
region on UT day 18-Dec were 15% depressed to 15% enhanced. Sporadic 
E was observed at times during the local day. MUFs are expected 
to be initially 15% depressed then recovering on 19-Dec and near 
predicted monthly values for 20-21 Dec. Mildly degraded HF conditions 
may be experienced for the southern Australian region during 
22-23 Dec in association with recurrent 27 day geomagnetic activity 
patterns.

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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