[Ips-dhfpr] ASWFC Daily HF Prop Report - 20 May 25 issued 2332 UT on 20 May 2025 [SEC=OFFICIAL]

[Australian Space Weather Forecasting Centre]

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

1. SUMMARY (20 MAY) 
Date   T index  Conditions    
20 May    87    Normal-fair    

Flares: none.

MUFs:
   Cocos Island Region:
      Near predicted monthly values during local day.
      Depressed by 15% during local night.
   Niue Island Region:
      Near predicted monthly values during local day.
      Depressed by 25% during local night.
   Northern Australian Region:
      Near predicted monthly values during local day.
      Depressed by 20% during local night.
   Southern Australian Region:
      Near predicted monthly values during local day.
      Depressed by 25% during local night.
   Antarctic Region (Casey/Davis/Mawson):
      Depressed by 15% over the UT day.

PCA Event : No event.

Monthly T index:
Month  T index
Apr      123
May      113
Jun      111


2. FORECAST (21 MAY - 23 MAY)
Date   T index  Conditions       MUFs                              
21 May    90    Normal           Depressed 15%/near predicted 
                                 monthly values
22 May    90    Normal           Depressed 15%/near predicted 
                                 monthly values    
23 May    90    Normal           Depressed 15%/near predicted 
                                 monthly values   

COMMENT: Maximum usable frequencies (MUFs) in the Australian 
region on UT day 20-May were near predicted monthly values during 
local day and 20-25% depressed during local night. Spread F was 
observed at Hobart during local night hours. MUFs are expected 
to be near predicted monthly values to 15% depressed over 21-23 
May. 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