SWS GRAFEX HF FREQUENCY PREDICTIONS ADDRESS NO. 1234 =============================================================================== Circuit: Karratha Perth Date: 23 April, 2026 T-index: 58 Bearings: 184 5 Distance: 1251 km First Mode |--------F r e q u e n c y (MHz)---------| Second Mode 1F 18-21 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 13.0 11.0 5.7 ASXMMMM BF%%%... 8.9 6.7 3.5 00 01 14.4 12.7 6.5 ASSXMMM MBFF%%%... 9.7 7.8 4.0 01 02 15.1 13.8 7.0 SSXXMM MMBFF%%%.. . 10.0 8.5 4.2 02 03 15.3 14.5 7.2 SSSXMM MMBBF%%%.. .. 10.2 8.9 4.4 03 04 15.3 14.7 7.3 ASSXXM MMBBF%%%.. .. 10.1 9.1 4.5 04 05 15.2 14.6 7.3 SSSXMM MMBBF%%%.. .. 10.2 9.0 4.4 05 06 14.8 14.2 7.1 SSSXMM MMBB%%%%.. . 10.1 8.8 4.3 06 07 15.0 13.3 6.7 SSXXMM MMBF%%%%.. . 10.1 8.2 4.1 07 08 14.6 11.9 6.1 ASSXMMM MMFF%%%%.. . 9.9 7.4 3.7 08 09 13.9 9.5 5.1 SSMMMMM MFF%%%%... 9.3 5.8 3.1 09 10 11.3 1.9 0.0 XMMMMMMMMF F%%%.... 7.6 1.2 0.0 10 11 8.5 1.9 0.0 XMMMMMMM%% %.... 5.9 1.2 0.0 11 12 7.3 1.9 0.0 XMMMMMM%%% ... 5.2 1.2 0.0 12 13 6.3 1.9 0.0 XMMMMM%%.. . 4.7 1.2 0.0 13 14 6.1 1.9 0.0 XMMMMM%%.. 4.6 1.2 0.0 14 15 6.2 1.9 0.0 XMMMMF%%.. 4.6 1.2 0.0 15 16 6.2 1.9 0.0 XMMMMF%%.. 4.6 1.2 0.0 16 17 6.0 1.9 0.0 XMMMM%%... 4.6 1.2 0.0 17 18 5.9 1.9 0.0 XMMMM%%... 4.4 1.2 0.0 18 19 5.8 1.9 0.0 XMMMM%%.. 4.1 1.2 0.0 19 20 5.6 1.9 0.0 XMMMM%%.. 3.9 1.2 0.0 20 21 4.9 1.9 0.0 XMMM%%.. 3.5 1.2 0.0 21 22 5.4 1.9 0.0 XMMMM%.. 4.0 1.2 0.0 22 23 9.7 7.3 4.1 ASMMMMF% %... 6.6 4.2 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) 23-Apr-2026 BoM Space Weather Services, Sydney Australia +61-2-9213-8000