SWS GRAFEX HF FREQUENCY PREDICTIONS ADDRESS NO. 1234 =============================================================================== Circuit: Perth district Date: 17 August, 2026 T-index: 60 Bearings: 0 180 Distance: 0-300 km First Mode |--------F r e q u e n c y (MHz)---------| Second Mode 1F 60-90 1E 40-90 1 5 10 15 20 25 30 35 40 ** NONE ** UT OWF EMUF ALF |...|....| ....|....| ....|....| ....|....| OWF EMUF ALF UT 00 5.6 2.3 2.0 AFFF%. 00 01 6.2 2.8 2.3 FFFF%. 01 02 6.5 3.1 2.5 AFFF%.. 02 03 6.7 3.2 2.6 AFFF%.. 03 04 6.9 3.3 2.7 AFFF%%. 04 05 6.9 3.3 2.6 AFFF%%. 05 06 6.9 3.2 2.6 AFFF%%. 06 07 6.9 3.0 2.4 BFFF%%. 07 08 6.7 2.6 2.2 FFFF%.. 08 09 6.2 2.0 1.8 AFFFF%. 09 10 5.2 0.4 0.0 FFFFF%.. 10 11 4.3 0.4 0.0 FFFF%.. 11 12 3.6 0.4 0.0 FFF%.. 12 13 3.4 0.4 0.0 FFF%. 13 14 3.3 0.4 0.0 FFF%. 14 15 3.2 0.4 0.0 FFF%. 15 16 3.2 0.4 0.0 FFF.. 16 17 3.1 0.4 0.0 FFF.. 17 18 3.1 0.4 0.0 FFF.. 18 19 2.9 0.4 0.0 FF%.. 19 20 2.8 0.4 0.0 FF%.. 20 21 2.7 0.4 0.0 FF%. 21 22 2.8 0.4 0.0 FF%. 22 23 4.3 1.2 1.2 FFF. 23 UT OWF EMUF ALF |...|....| ....|....| ....|....| ....|....| OWF EMUF ALF UT =============================================================================== |. USABLE LESS THAN 50% OF DAYS |% USABLE 50% TO 90% OF DAYS | |B BOTH E and F MODES 90% OF DAYS |M MIXED FIRST AND SECOND F MODES | |F FIRST F MODE ONLY |E E-LAYER PROPAGATION |P 90% E and 50-90% F | |S SECOND MODES ONLY |A HIGH ABSORPTION |X COMPLEX MODES | (c) 17-Aug-2026 BoM Space Weather Services, Sydney Australia +61-2-9213-8000