SWS GRAFEX HF FREQUENCY PREDICTIONS ADDRESS NO. 1234 =============================================================================== Circuit: Karratha Perth Date: 12 April, 2026 T-index: 75 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 13.8 11.5 6.1 ASSXMMM MFF%%%%.. 9.4 7.1 3.7 00 01 15.1 13.3 6.8 SSXXMM MMBFF%%%.. . 10.1 8.2 4.2 01 02 16.0 14.3 7.3 SSSXMM MMBBF%%%%. ... 10.6 8.9 4.4 02 03 16.3 15.0 7.5 ASSXXM MMMBBF%%%. ... 10.8 9.3 4.6 03 04 16.4 15.2 7.7 ASSXXM MMMBBF%%%. ... 10.9 9.4 4.7 04 05 16.4 15.1 7.6 ASSXXM MMMBBF%%%. ... 11.1 9.4 4.6 05 06 15.4 14.7 7.4 ASSXXM MMMBF%%%%. .. 10.7 9.1 4.5 06 07 15.2 13.8 7.1 SSSXMM MMMFF%%%%. .. 10.3 8.6 4.3 07 08 14.6 12.5 6.5 ASSXMMM MMFF%%%%.. . 10.0 7.7 3.9 08 09 14.4 10.2 5.5 SSXMMMM MMFF%%%%.. . 9.7 6.3 3.3 09 10 12.4 2.0 0.0 XMMMMMMMMM MF%%%%.... 8.3 1.2 0.0 10 11 9.6 2.0 0.0 XMMMMMMMM% %%%.... 6.6 1.2 0.0 11 12 8.3 2.0 0.0 XMMMMMMM%% %... 5.9 1.2 0.0 12 13 7.1 2.0 0.0 XMMMMMM%%% .. 5.2 1.2 0.0 13 14 6.9 2.0 0.0 XMMMMM%%%. . 5.1 1.2 0.0 14 15 6.9 2.0 0.0 XMMMMM%%%. . 5.1 1.2 0.0 15 16 6.8 2.0 0.0 XMMMMM%%%. . 5.0 1.2 0.0 16 17 6.7 2.0 0.0 XMMMMM%%.. . 5.0 1.2 0.0 17 18 6.5 2.0 0.0 XMMMMM%%.. 4.8 1.2 0.0 18 19 6.2 2.0 0.0 XMMMMM%%.. 4.5 1.2 0.0 19 20 5.8 2.0 0.0 XMMMM%%.. 4.2 1.2 0.0 20 21 5.1 2.0 0.0 XMMMM%.. 3.7 1.2 0.0 21 22 5.8 2.0 0.0 XMMMM%%.. 4.4 1.2 0.0 22 23 10.5 8.3 4.6 ASMMMMFF %%... 7.1 4.9 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) 12-Apr-2026 BoM Space Weather Services, Sydney Australia +61-2-9213-8000