SWS GRAFEX HF FREQUENCY PREDICTIONS ADDRESS NO. 1234 =============================================================================== Circuit: Karratha Perth Date: 25 April, 2026 T-index: 70 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 13.6 11.1 5.8 ASXMMMM MFF%%%... 9.2 6.7 3.6 00 01 15.1 12.9 6.6 ASSXMMM MMFFF%%%.. . 10.1 7.9 4.0 01 02 16.0 14.0 7.1 SSSXMM MMBBF%%%%. .. 10.6 8.6 4.3 02 03 16.1 14.6 7.4 ASSXMM MMBBFF%%%. ... 10.7 9.0 4.5 03 04 16.1 14.9 7.5 ASSXXM MMBBFF%%%. ... 10.7 9.2 4.5 04 05 15.9 14.8 7.4 ASSXXM MMBBF%%%%. .. 10.7 9.2 4.5 05 06 15.5 14.3 7.2 SSSXMM MMBBF%%%.. .. 10.6 8.9 4.4 06 07 15.5 13.5 6.9 SSXXMM MMBFF%%%%. .. 10.5 8.3 4.2 07 08 15.1 12.0 6.3 ASSXMMM MMFFF%%%.. . 10.3 7.4 3.8 08 09 14.5 9.6 5.2 SSMMMMM MMFF%%%%.. . 9.7 5.8 3.2 09 10 11.9 2.0 0.0 XMMMMMMMMM F%%%%.... 8.0 1.2 0.0 10 11 9.1 2.0 0.0 XMMMMMMMF% %%.... 6.3 1.2 0.0 11 12 7.7 2.0 0.0 XMMMMMM%%% ... 5.5 1.2 0.0 12 13 6.7 2.0 0.0 XMMMMM%%%. .. 4.9 1.2 0.0 13 14 6.5 2.0 0.0 XMMMMM%%.. . 4.8 1.2 0.0 14 15 6.4 2.0 0.0 XMMMMM%%.. 4.8 1.2 0.0 15 16 6.4 2.0 0.0 XMMMMM%%.. 4.7 1.2 0.0 16 17 6.2 2.0 0.0 XMMMMM%%.. 4.7 1.2 0.0 17 18 6.1 2.0 0.0 XMMMMM%%.. 4.5 1.2 0.0 18 19 5.8 2.0 0.0 XMMMM%%... 4.2 1.2 0.0 19 20 5.6 2.0 0.0 XMMMM%%.. 3.9 1.2 0.0 20 21 5.0 2.0 0.0 XMMMM%.. 3.6 1.2 0.0 21 22 5.5 2.0 0.0 XMMMM%%. 4.2 1.2 0.0 22 23 10.1 7.2 4.1 ASMMMMFF %%.. 6.8 4.1 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) 25-Apr-2026 BoM Space Weather Services, Sydney Australia +61-2-9213-8000