SWS GRAFEX HF FREQUENCY PREDICTIONS ADDRESS NO. 1234 =============================================================================== Circuit: Karratha Perth Date: 3 April, 2026 T-index: 50 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 36-42 2E 14 UT OWF EMUF ALF |...|....| ....|....| ....|....| ....|....| OWF EMUF ALF UT 00 12.1 11.5 5.9 ASXXMMM BF%%... 8.3 7.1 3.6 00 01 13.2 13.1 6.6 ASSXXMM BBB%%%... 8.9 8.1 4.0 01 02 13.8 14.1 7.0 SSXXMM MBBP%%%... 9.1 8.7 4.3 02 03 14.1 14.7 7.3 SSSXXM MBBB%%%... 9.3 9.1 4.4 03 04 14.2 14.9 7.4 ASSXXM MBBB%%%... 9.4 9.2 4.5 04 05 14.3 14.8 7.4 ASSXXM MBBB%%%... 9.6 9.2 4.5 05 06 13.9 14.4 7.2 SSSXMM MBBP%%%... 9.5 8.9 4.4 06 07 14.0 13.6 6.8 SSXXMM MBB%%%%... 9.4 8.4 4.2 07 08 13.7 12.3 6.3 ASSXMMM MBF%%%%... 9.2 7.6 3.8 08 09 13.3 10.2 5.4 SSXMMMM MFF%%%... 8.9 6.3 3.3 09 10 11.2 4.5 2.7 AMMMMMMMF F%%%.... 7.5 2.7 1.7 10 11 8.7 1.9 0.0 XMMMMMMM%% %%... 6.0 1.1 0.0 11 12 7.3 1.9 0.0 XMMMMMM%%% ... 5.2 1.1 0.0 12 13 6.4 1.9 0.0 XMMMMM%%%. . 4.7 1.1 0.0 13 14 6.1 1.9 0.0 XMMMMM%%.. 4.6 1.1 0.0 14 15 6.3 1.9 0.0 XMMMMM%%.. 4.7 1.1 0.0 15 16 6.3 1.9 0.0 XMMMMM%%.. 4.7 1.1 0.0 16 17 6.2 1.9 0.0 XMMMMF%%.. 4.6 1.1 0.0 17 18 6.1 1.9 0.0 XMMMMF%%.. 4.6 1.1 0.0 18 19 6.0 1.9 0.0 XMMMM%%... 4.3 1.1 0.0 19 20 5.4 1.9 0.0 XMMMM%%.. 3.9 1.1 0.0 20 21 4.8 1.9 0.0 XMMM%%.. 3.5 1.1 0.0 21 22 5.7 1.9 0.0 XMMMM%%.. 4.2 1.1 0.0 22 23 9.5 8.6 4.7 ASXMMBF% %... 6.5 5.2 2.9 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) 3-Apr-2026 BoM Space Weather Services, Sydney Australia +61-2-9213-8000