SWS GRAFEX HF FREQUENCY PREDICTIONS ADDRESS NO. 1234 =============================================================================== Circuit: Karratha Perth Date: 22 April, 2026 T-index: 65 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 13.4 11.1 5.8 ASXMMMM MFF%%%... 9.1 6.8 3.6 00 01 14.9 12.9 6.6 ASSXMMM MMFF%%%%.. . 10.0 7.9 4.0 01 02 15.8 14.0 7.1 SSSXMM MMBBF%%%%. .. 10.4 8.6 4.3 02 03 15.9 14.6 7.3 ASSXMM MMBBF%%%%. .. 10.6 9.0 4.5 03 04 15.9 14.9 7.4 ASSXXM MMBBF%%%%. .. 10.6 9.2 4.5 04 05 15.8 14.8 7.4 ASSXXM MMBBF%%%%. .. 10.6 9.1 4.5 05 06 15.1 14.3 7.2 SSSXMM MMBBF%%%.. .. 10.3 8.9 4.4 06 07 15.1 13.5 6.8 SSXXMM MMBFF%%%%. .. 10.3 8.3 4.2 07 08 14.8 12.1 6.2 ASSXMMM MMFF%%%%.. . 10.0 7.4 3.8 08 09 14.1 9.6 5.2 SSMMMMM MFFF%%%... 9.5 5.9 3.2 09 10 11.7 1.9 0.0 XMMMMMMMMM F%%%%... 7.9 1.2 0.0 10 11 9.0 1.9 0.0 XMMMMMMM%% %%.... 6.2 1.2 0.0 11 12 7.7 1.9 0.0 XMMMMMM%%% ... 5.4 1.2 0.0 12 13 6.6 1.9 0.0 XMMMMM%%%. . 4.9 1.2 0.0 13 14 6.4 1.9 0.0 XMMMMM%%.. . 4.8 1.2 0.0 14 15 6.4 1.9 0.0 XMMMMM%%.. 4.8 1.2 0.0 15 16 6.4 1.9 0.0 XMMMMM%%.. 4.7 1.2 0.0 16 17 6.2 1.9 0.0 XMMMMM%%.. 4.7 1.2 0.0 17 18 6.1 1.9 0.0 XMMMMF%%.. 4.5 1.2 0.0 18 19 5.9 1.9 0.0 XMMMM%%... 4.2 1.2 0.0 19 20 5.7 1.9 0.0 XMMMM%%.. 4.0 1.2 0.0 20 21 5.0 1.9 0.0 XMMM%%.. 3.6 1.2 0.0 21 22 5.5 1.9 0.0 XMMMM%%. 4.1 1.2 0.0 22 23 10.0 7.4 4.2 ASMMMMF% %%.. 6.8 4.3 2.6 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) 22-Apr-2026 BoM Space Weather Services, Sydney Australia +61-2-9213-8000