[Ips-dhfpr] ASWFC Daily HF Prop Report - 17 April 26 issued 2330 UT on 17 Apr 2026 [SEC=OFFICIAL]

[Australian Space Weather Forecasting Centre]

SUBJ: ASWFC DAILY HF PROPAGATION REPORT
ISSUED AT 2330UT/17 APRIL 2026
FROM THE AUSTRALIAN SPACE WEATHER FORECAST CENTRE
AUSTRALIAN REGION SUMMARY AND FORECAST

1. SUMMARY (17 APRIL) 
Date   T index  Conditions    
17 Apr    66    Fair-normal    

Flares: none.

MUFs:
   Cocos Island Region:
      Enhanced by 25% during local day.
      Near predicted monthly values during local night.
      Depressed by 20% after local dawn.
   Niue Island Region:
      Depressed by 15% during local day.
      Depressed by 30% during local night.
   Northern Australian Region:
      Near predicted monthly values during local day.
      Depressed by 25% during local night.
   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
Mar      92
Apr      83
May      81


2. FORECAST (18 APRIL - 20 APRIL)
Date   T index  Conditions       MUFs                              
18 Apr    45    Fair             Depressed 20 to 30%/near predicted 
                                 monthly values
19 Apr    55    Fair             Depressed 20 to 30%/near predicted 
                                 monthly values    
20 Apr    65    Fair-normal      Depressed 10 to 15%/near predicted 
                                 monthly values   

COMMENT: ASWFC Preliminary HF Communications Warning 36 was issued 
on 16 April and is current for 18-20 Apr. Maximum Usable Frequencies 
(MUFs) in the Australian region on UT day 17-Apr were mostly 
near predicted monthly values. Depressions of up to 25% were 
observed during local night hours in the Northern Australian 
region, and up to 30% at Niue Island. MUF depressions of up to 
20-30% are forecast over 18-19 Apr due to anticipated geomagnetic 
activity induced by a coronal hole wind stream. These depressions 
will begin to trend toward predicted monthly values on 20-Apr 
as the effects of the high speed wind stream begin to subside.

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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