SWS GRAFEX HF FREQUENCY PREDICTIONS ADDRESS NO. 1234 =============================================================================== Circuit: Karratha Perth Date: 28 March, 2026 T-index: 95 Bearings: 184 5 Distance: 1251 km First Mode |--------F r e q u e n c y (MHz)---------| Second Mode 1F 19-24 1E 5 1 5 10 15 20 25 30 35 40 2F 37-44 2E 14 UT OWF EMUF ALF |...|....| ....|....| ....|....| ....|....| OWF EMUF ALF UT 00 14.3 12.3 6.5 ASSXMMM MBFF%%%.. 9.6 7.6 4.0 00 01 15.6 13.9 7.2 SSSXMM MMBFF%%%.. . 10.4 8.6 4.4 01 02 16.1 14.9 7.7 ASSXXM MMBBFF%%%. .. 10.8 9.3 4.7 02 03 16.3 15.5 7.9 ASSXXM MMMBBF%%%. .. 11.1 9.6 4.8 03 04 16.4 15.8 8.1 ASSSXM MMMBBF%%%. .. 11.3 9.8 4.9 04 05 16.5 15.7 8.0 ASSXXM MMMBBF%%%. .. 11.5 9.7 4.9 05 06 16.0 15.3 7.8 ASSXXM MMMBB%%%%. .. 11.2 9.5 4.8 06 07 15.8 14.5 7.5 ASSXMM MMMBF%%%%. .. 10.9 9.0 4.5 07 08 15.5 13.1 6.9 SSXXMM MMBFF%%%.. . 10.6 8.2 4.2 08 09 15.4 11.0 6.0 ASXMMMM MMFFF%%%.. . 10.3 6.8 3.6 09 10 13.8 6.0 3.6 SMMMMMMM MFF%%%%... 9.3 3.7 2.1 10 11 11.6 2.1 0.0 XMMMMMMMMM F%%%%... 8.0 1.3 0.0 11 12 10.0 2.1 0.0 XMMMMMMMM% %%... 7.2 1.3 0.0 12 13 8.9 2.1 0.0 XMMMMMMM%% %... 6.4 1.3 0.0 13 14 8.2 2.1 0.0 XMMMMMMF%% ... 6.0 1.3 0.0 14 15 8.0 2.1 0.0 XMMMMMM%%% .. 5.8 1.3 0.0 15 16 7.8 2.1 0.0 XMMMMMM%%% .. 5.7 1.3 0.0 16 17 7.7 2.1 0.0 XMMMMMM%%. .. 5.6 1.3 0.0 17 18 7.3 2.1 0.0 XMMMMMF%%. . 5.4 1.3 0.0 18 19 6.9 2.1 0.0 XMMMMM%%%. . 5.2 1.3 0.0 19 20 6.2 2.1 0.0 XMMMMM%%. 4.6 1.3 0.0 20 21 5.6 2.1 0.0 XMMMM%%.. 4.2 1.3 0.0 21 22 6.9 2.1 0.0 XMMMMM%%.. 5.2 1.3 0.0 22 23 11.4 9.4 5.2 SSMMMMF F%%.. 7.6 5.7 3.2 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) 28-Mar-2026 BoM Space Weather Services, Sydney Australia +61-2-9213-8000