HF Fadeout Warning

(last updated 11 Oct 2026 03:00 UT)

SUBJ: ASWFC HF RADIO COMMUNICATIONS WARNING 26/86 ISSUED AT 2318UT/10 OCTOBER 2026 BY THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE. Solar flare activity is expected to be at R1-R2 levels over 10-12 Oct primarily due to the observed flare activity from active region 4549. Shortwave fadeouts are probable. DEGRADED HF PROPAGATION CONDITIONS EXPECTED FROM 10-12 OCTOBER 2026 IF COMMS DIFFICULTIES EXPERIENCED TRY A HIGHER FREQUENCY BAND _____________________________________________________________ SOLAR ACTIVITY FORECAST HF COMMS FADEOUTS 10 Oct: R1-R2 Probable 11 Oct: R1-R2 Probable 12 Oct: R1-R2 Probable Note: An ASWFC MUF depression HF Warning and ASWFC shortwave fadeout HF Warning are both current. Shortwave fadeouts degrade lower shortwave radio frequencies first (through increased ionospheric absorption) and the usual strategy during shortwave fadeouts is to try a higher frequency. In contrast, during periods of ionospheric MUF depression, the upper frequencies are degraded first and the usual strategy is to use a lower frequency. In general use a lower frequency if you are having trouble with your normal workable frequency. If a shortwave fadeout occurs during a period when ionospheric MUFs are depressed the available HF bandwidth will be "squeezed", with increased absorption raising the lowest usable frequency and the ionospheric depression lowering the highest usable frequency. Under such conditions it is suggested that the HF communicator operates on the highest usable frequency, even though this may well be in fact lower than what is normally supported for that particular circuit.