SWS GRAFEX HF FREQUENCY PREDICTIONS ADDRESS NO. 1234 =============================================================================== Circuit: Karratha Perth Date: 9 April, 2026 T-index: 90 Bearings: 184 5 Distance: 1251 km First Mode |--------F r e q u e n c y (MHz)---------| Second Mode 1F 18-23 1E 5 1 5 10 15 20 25 30 35 40 2F 37-43 2E 14 UT OWF EMUF ALF |...|....| ....|....| ....|....| ....|....| OWF EMUF ALF UT 00 14.8 11.8 6.3 ASSXMMM MFFF%%%... 10.0 7.3 3.8 00 01 16.1 13.6 7.0 SSXXMM MMBFFF%%%. .. 10.8 8.4 4.3 01 02 16.9 14.6 7.5 ASSXMM MMMBFF%%%% ... 11.2 9.0 4.6 02 03 16.9 15.3 7.8 ASSXXM MMMBBF%%%% ... 11.4 9.4 4.7 03 04 17.0 15.5 7.9 ASSXXM MMMBBF%%%% ... 11.5 9.6 4.8 04 05 16.9 15.4 7.8 ASSXXM MMMBBF%%%% ... 11.7 9.6 4.8 05 06 16.2 15.0 7.7 ASSXXM MMMBBF%%%. .. 11.3 9.3 4.7 06 07 16.1 14.1 7.3 SSSXMM MMMBFF%%%% .. 11.1 8.8 4.4 07 08 15.6 12.8 6.7 SSXMMM MMMFF%%%%. .. 10.8 7.9 4.1 08 09 15.5 10.5 5.7 ASXMMMM MMFFF%%%%. . 10.4 6.5 3.5 09 10 13.5 2.1 0.0 XMMMMMMMMM MFF%%%%... 9.1 1.3 0.9 10 11 10.9 2.1 0.0 XMMMMMMMMF %%%%... 7.5 1.3 0.0 11 12 9.4 2.1 0.0 XMMMMMMMF% %%... 6.7 1.3 0.0 12 13 8.2 2.1 0.0 XMMMMMMF%% %.. 6.0 1.3 0.0 13 14 7.8 2.1 0.0 XMMMMMM%%% .. 5.7 1.3 0.0 14 15 7.5 2.1 0.0 XMMMMMM%%. .. 5.5 1.3 0.0 15 16 7.4 2.1 0.0 XMMMMMF%%. .. 5.4 1.3 0.0 16 17 7.2 2.1 0.0 XMMMMMF%%. . 5.3 1.3 0.0 17 18 7.0 2.1 0.0 XMMMMM%%%. . 5.2 1.3 0.0 18 19 6.7 2.1 0.0 XMMMMM%%.. 4.8 1.3 0.0 19 20 6.1 2.1 0.0 XMMMMM%%. 4.4 1.3 0.0 20 21 5.5 2.1 0.0 XMMMM%%. 4.0 1.3 0.0 21 22 6.4 2.1 0.0 XMMMMM%%. 4.8 1.3 0.0 22 23 11.3 8.6 4.8 ASXMMMMF F%%.. 7.6 5.2 3.0 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) 9-Apr-2026 BoM Space Weather Services, Sydney Australia +61-2-9213-8000