SWS GRAFEX HF FREQUENCY PREDICTIONS ADDRESS NO. 1234 =============================================================================== Circuit: Broome Perth Date: 21 April, 2026 T-index: 78 Bearings: 201 24 Distance: 1680 km First Mode |--------F r e q u e n c y (MHz)---------| Second Mode 1F 12-15 1E 2 1 5 10 15 20 25 30 35 40 2F 28-33 2E 10 UT OWF EMUF ALF |...|....| ....|....| ....|....| ....|....| OWF EMUF ALF UT 00 17.9 13.5 7.9 ASSXMM MMMFFFF%%% %... 11.4 8.7 4.7 00 01 19.6 15.3 8.8 SSSXM MMMMBFFFF% %%%.... 12.3 10.0 5.2 01 02 20.9 16.5 9.3 ASSSX MMMMMBFFFF %%%%.... 12.8 10.8 5.5 02 03 21.1 17.1 9.6 ASSSX XMMMMBBFFF F%%%.... 13.0 11.3 5.6 03 04 21.2 17.3 9.7 ASSSX XMMMMBBFFF F%%%..... 12.9 11.5 5.7 04 05 20.8 17.1 9.6 ASSSX XMMMMBBFFF %%%%.... 12.9 11.4 5.6 05 06 20.0 16.5 9.3 ASSSX MMMMMBFFF% %%%..... 12.6 11.0 5.5 06 07 19.8 15.5 8.8 SSSXX MMMMMFFFF% %%%%..... 12.3 10.3 5.1 07 08 19.0 13.7 8.0 ASSXXM MMMMFFFF%% %%%.... 11.9 9.2 4.6 08 09 18.4 10.5 6.4 ASSMMMM MMMMFFFF%% %%..... 11.6 7.0 3.7 09 10 14.7 2.3 0.0 XMMMMMMMMM MMFF%%%%%. ..... 9.7 1.5 0.0 10 11 10.9 2.3 0.0 XMMMMMMMMM %%%%%..... .. 7.6 1.5 0.0 11 12 9.6 2.3 0.0 XMMMMMMMM% %%%...... 6.7 1.5 0.0 12 13 8.3 2.3 0.0 XMMMMMMM%% %%..... 5.9 1.5 0.0 13 14 8.2 2.3 0.0 XMMMMMMF%% %.... 5.7 1.5 0.0 14 15 8.1 2.3 0.0 XMMMMMMF%% %.... 5.7 1.5 0.0 15 16 8.1 2.3 0.0 XMMMMMMF%% %.... 5.6 1.5 0.0 16 17 7.7 2.3 0.0 XMMMMMM%%% .... 5.5 1.5 0.0 17 18 7.5 2.3 0.0 XMMMMMM%%% .... 5.4 1.5 0.0 18 19 7.0 2.3 0.0 XMMMMM%%%% ... 4.8 1.5 0.0 19 20 6.4 2.3 0.0 XMMMMM%%%. .. 4.5 1.5 0.0 20 21 5.8 2.3 0.0 XMMMM%%%.. . 4.1 1.5 0.0 21 22 7.3 2.3 0.0 XMMMMMF%%. .. 5.2 1.5 0.0 22 23 14.3 10.0 6.2 ASSMMMM FFFF%%%.. 8.8 6.0 3.8 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) 21-Apr-2026 BoM Space Weather Services, Sydney Australia +61-2-9213-8000