SWS GRAFEX HF FREQUENCY PREDICTIONS ADDRESS NO. 1234 =============================================================================== Circuit: Karratha Perth Date: 10 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 37-42 2E 14 UT OWF EMUF ALF |...|....| ....|....| ....|....| ....|....| OWF EMUF ALF UT 00 13.2 11.5 6.0 ASXMMMM MFF%%%... 9.0 7.0 3.7 00 01 14.4 13.2 6.7 SSXXMM MBBF%%%... 9.7 8.1 4.1 01 02 15.3 14.2 7.2 SSSXMM MMBBF%%%.. .. 10.1 8.8 4.4 02 03 15.5 14.8 7.4 ASSXXM MMBBF%%%%. .. 10.3 9.2 4.5 03 04 15.6 15.1 7.5 ASSXXM MMBBB%%%%. .. 10.3 9.3 4.6 04 05 15.6 15.0 7.5 ASSXXM MMBBB%%%%. .. 10.5 9.3 4.6 05 06 14.9 14.5 7.3 SSSXMM MMBB%%%%.. . 10.2 9.0 4.4 06 07 14.8 13.7 7.0 SSXXMM MMBF%%%%.. . 10.0 8.5 4.2 07 08 14.4 12.4 6.4 ASSXMMM MMFF%%%%.. . 9.7 7.7 3.9 08 09 14.1 10.1 5.4 SSXMMMM MFFF%%%%.. 9.4 6.3 3.3 09 10 11.8 1.9 0.0 XMMMMMMMMM F%%%%%... 8.0 1.2 0.0 10 11 9.1 1.9 0.0 XMMMMMMMF% %%.... 6.3 1.2 0.0 11 12 7.8 1.9 0.0 XMMMMMM%%% %... 5.6 1.2 0.0 12 13 6.8 1.9 0.0 XMMMMM%%%. .. 5.0 1.2 0.0 13 14 6.5 1.9 0.0 XMMMMM%%%. . 4.9 1.2 0.0 14 15 6.6 1.9 0.0 XMMMMM%%.. . 4.9 1.2 0.0 15 16 6.6 1.9 0.0 XMMMMM%%.. 4.8 1.2 0.0 16 17 6.4 1.9 0.0 XMMMMM%%.. 4.8 1.2 0.0 17 18 6.3 1.9 0.0 XMMMMM%%.. 4.7 1.2 0.0 18 19 6.1 1.9 0.0 XMMMMM%%.. 4.4 1.2 0.0 19 20 5.7 1.9 0.0 XMMMM%%.. 4.1 1.2 0.0 20 21 5.0 1.9 0.0 XMMM%%.. 3.6 1.2 0.0 21 22 5.7 1.9 0.0 XMMMM%%.. 4.3 1.2 0.0 22 23 10.1 8.3 4.6 ASMMMMFF %%.. 6.9 5.0 2.8 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) 10-Apr-2026 BoM Space Weather Services, Sydney Australia +61-2-9213-8000