SWS GRAFEX HF FREQUENCY PREDICTIONS ADDRESS NO. 1234 =============================================================================== Circuit: Karratha Perth Date: 16 August, 2026 T-index: 55 Bearings: 184 5 Distance: 1251 km First Mode |--------F r e q u e n c y (MHz)---------| Second Mode 1F 18-22 1E 5 1 5 10 15 20 25 30 35 40 2F 36-41 2E 14 UT OWF EMUF ALF |...|....| ....|....| ....|....| ....|....| OWF EMUF ALF UT 00 11.6 10.8 5.6 ASXMMMB F%%... 7.8 6.6 3.5 00 01 12.9 12.6 6.4 ASSXMMM BB%%%... 8.6 7.7 3.9 01 02 13.3 13.7 6.9 SSXXMM BBB%%... 8.7 8.4 4.2 02 03 13.4 14.3 7.1 SSSXMM BBBP%%... 8.9 8.9 4.4 03 04 13.1 14.6 7.2 SSSXMM BBBP%... 8.6 9.0 4.4 04 05 12.8 14.5 7.2 SSSXMM BBPP%... 8.5 9.0 4.4 05 06 12.6 14.0 7.0 SSXXMM BBPP%.. 8.3 8.7 4.3 06 07 12.6 13.2 6.7 SSXXMM BBP%... 8.1 8.2 4.1 07 08 12.1 11.8 6.1 ASSXMMB BF%%... 7.9 7.3 3.7 08 09 12.0 9.3 5.0 ASXMMMMF F%%%.. 7.9 5.7 3.0 09 10 10.1 1.9 0.0 XMMMMMMMFF %%... 6.9 1.2 0.0 10 11 7.9 1.9 0.0 XMMMMMM%%% ... 5.6 1.2 0.0 11 12 6.7 1.9 0.0 XMMMMM%%.. . 4.8 1.2 0.0 12 13 6.0 1.9 0.0 XMMMM%%... 4.4 1.2 0.0 13 14 5.9 1.9 0.0 XMMMM%%... 4.3 1.2 0.0 14 15 5.7 1.9 0.0 XMMMM%%.. 4.2 1.2 0.0 15 16 5.5 1.9 0.0 XMMMM%%.. 4.1 1.2 0.0 16 17 5.4 1.9 0.0 XMMMM%%.. 4.1 1.2 0.0 17 18 5.2 1.9 0.0 XMMMM%%.. 3.9 1.2 0.0 18 19 5.1 1.9 0.0 XMMMM%%.. 3.6 1.2 0.0 19 20 4.7 1.9 0.0 XMMM%%.. 3.3 1.2 0.0 20 21 4.3 1.9 0.0 XMMM%... 3.1 1.2 0.0 21 22 4.6 1.9 0.0 XMMM%.. 3.5 1.2 0.0 22 23 8.7 6.9 3.9 AMMMMF%% .. 6.0 3.9 2.5 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) 16-Aug-2026 BoM Space Weather Services, Sydney Australia +61-2-9213-8000