SWS GRAFEX HF FREQUENCY PREDICTIONS ADDRESS NO. 1234 =============================================================================== Circuit: Karratha Perth Date: 1 May, 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 14.1 11.0 5.8 ASXMMMM MFFF%%... 9.5 6.7 3.6 00 01 15.9 12.9 6.7 SSXMMM MMFFF%%%%. .. 10.5 7.9 4.1 01 02 16.7 14.0 7.2 SSSXMM MMMBFF%%%% ... 11.1 8.7 4.4 02 03 16.9 14.7 7.4 ASSXXM MMMBFF%%%% ... 11.3 9.1 4.5 03 04 16.7 15.0 7.5 ASSXXM MMMBBF%%%. ... 11.1 9.2 4.6 04 05 16.4 14.9 7.5 ASSXXM MMMBFF%%%. ... 11.1 9.2 4.6 05 06 15.9 14.4 7.3 ASSXMM MMMBF%%%%. .. 10.9 8.9 4.5 06 07 16.0 13.5 6.9 SSXXMM MMMFF%%%%. ... 10.8 8.3 4.2 07 08 15.7 12.0 6.3 ASSXMMM MMMFF%%%%. .. 10.7 7.4 3.8 08 09 15.1 9.4 5.1 SSMMMMM MMFFF%%%.. . 10.1 5.7 3.1 09 10 12.5 2.0 0.0 XMMMMMMMMM FF%%%.... 8.4 1.3 0.0 10 11 9.7 2.0 0.0 XMMMMMMMF% %%.... 6.6 1.3 0.0 11 12 8.1 2.0 0.0 XMMMMMMF%% .... 5.7 1.3 0.0 12 13 7.1 2.0 0.0 XMMMMMF%%. .. 5.1 1.3 0.0 13 14 6.7 2.0 0.0 XMMMMM%%.. . 5.0 1.3 0.0 14 15 6.4 2.0 0.0 XMMMMM%%.. 4.8 1.3 0.0 15 16 6.4 2.0 0.0 XMMMMM%%.. 4.7 1.3 0.0 16 17 6.2 2.0 0.0 XMMMMM%%.. 4.7 1.3 0.0 17 18 6.1 2.0 0.0 XMMMMM%%.. 4.5 1.3 0.0 18 19 5.8 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 5.6 2.0 0.0 XMMMM%%. 4.3 1.3 0.0 22 23 10.4 6.8 3.9 AMMMMMFF %%.. 7.0 3.7 2.5 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) 1-May-2026 BoM Space Weather Services, Sydney Australia +61-2-9213-8000