SWS GRAFEX HF FREQUENCY PREDICTIONS ADDRESS NO. 1234 =============================================================================== Circuit: Karratha Perth Date: 27 April, 2026 T-index: 80 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 37-41 2E 14 UT OWF EMUF ALF |...|....| ....|....| ....|....| ....|....| OWF EMUF ALF UT 00 14.2 11.1 5.9 ASXMMMM MFFF%%%.. 9.6 6.8 3.6 00 01 16.0 13.0 6.7 SSXMMM MMBFF%%%%. .. 10.6 8.0 4.1 01 02 16.8 14.1 7.2 SSSXMM MMMBFF%%%% ... 11.1 8.7 4.4 02 03 16.8 14.8 7.5 ASSXXM MMMBFF%%%% ... 11.2 9.1 4.6 03 04 16.7 15.0 7.6 ASSXXM MMMBBF%%%. ... 11.1 9.3 4.6 04 05 16.4 14.9 7.5 ASSXXM MMMBFF%%%. ... 11.1 9.2 4.6 05 06 15.8 14.5 7.3 ASSXMM MMMBF%%%%. .. 10.9 9.0 4.5 06 07 15.8 13.6 7.0 SSXXMM MMMFF%%%%. .. 10.8 8.4 4.2 07 08 15.5 12.1 6.3 ASSXMMM MMMFF%%%%. .. 10.5 7.5 3.9 08 09 15.0 9.6 5.2 SSMMMMM MMFF%%%%.. . 10.1 5.8 3.2 09 10 12.5 2.0 0.0 XMMMMMMMMM FF%%%%... 8.4 1.3 0.0 10 11 9.8 2.0 0.0 XMMMMMMMF% %%%... 6.8 1.3 0.0 11 12 8.3 2.0 0.0 XMMMMMMF%% %... 5.8 1.3 0.0 12 13 7.2 2.0 0.0 XMMMMMF%%. .. 5.2 1.3 0.0 13 14 6.8 2.0 0.0 XMMMMM%%%. . 5.1 1.3 0.0 14 15 6.6 2.0 0.0 XMMMMM%%.. . 4.9 1.3 0.0 15 16 6.5 2.0 0.0 XMMMMM%%.. . 4.8 1.3 0.0 16 17 6.3 2.0 0.0 XMMMMM%%.. 4.8 1.3 0.0 17 18 6.2 2.0 0.0 XMMMMM%%.. 4.6 1.3 0.0 18 19 5.9 2.0 0.0 XMMMM%%... 4.2 1.3 0.0 19 20 5.6 2.0 0.0 XMMMM%%.. 4.0 1.3 0.0 20 21 5.0 2.0 0.0 XMMMM%.. 3.7 1.3 0.0 21 22 5.7 2.0 0.0 XMMMM%%. 4.3 1.3 0.0 22 23 10.5 7.2 4.1 ASMMMMFF %%.. 7.1 4.0 2.6 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) 27-Apr-2026 BoM Space Weather Services, Sydney Australia +61-2-9213-8000