SWS GRAFEX HF FREQUENCY PREDICTIONS ADDRESS NO. 1234 =============================================================================== Circuit: Karratha Perth Date: 27 February, 2026 T-index: 100 Bearings: 184 5 Distance: 1251 km First Mode |--------F r e q u e n c y (MHz)---------| Second Mode 1F 19-26 1E 5 1 5 10 15 20 25 30 35 40 2F 37-47 2E 14 UT OWF EMUF ALF |...|....| ....|....| ....|....| ....|....| OWF EMUF ALF UT 00 12.0 13.0 6.9 SSXXMM BPP%.... 8.1 8.1 4.2 00 01 12.8 14.5 7.5 ASSXMM BBPP%.... 8.7 9.0 4.6 01 02 13.1 15.4 8.0 ASSXXM MBBPP%... 9.1 9.6 4.8 02 03 13.7 16.0 8.2 ASSSXM MBBPPP... 9.6 9.9 5.0 03 04 13.9 16.2 8.3 ASSSXX MBBPPP%... 9.8 10.1 5.0 04 05 14.1 16.1 8.3 ASSSXM MMBBPP%... 9.9 10.0 5.0 05 06 14.2 15.7 8.1 ASSSXM MMBBP%%... 9.9 9.8 4.9 06 07 13.9 15.0 7.8 ASSXXM MMBPP%%... 9.7 9.3 4.7 07 08 13.6 13.8 7.2 SSSXMM MBB%%%%... 9.4 8.6 4.4 08 09 13.2 12.0 6.4 ASSXMMM MBF%%%... 9.2 7.5 3.9 09 10 12.4 8.7 4.9 ASXMMMMM FF%%%... 8.7 5.3 3.0 10 11 11.6 2.1 0.0 XMMMMMMMMM F%%%... 8.1 1.3 0.0 11 12 10.4 2.1 0.0 XMMMMMMMMF %%%.. 7.4 1.3 0.0 12 13 9.6 2.1 0.0 XMMMMMMMF% %%.. 6.9 1.3 0.0 13 14 8.7 2.1 0.0 XMMMMMMM%% %.. 6.4 1.3 0.0 14 15 8.4 2.1 0.0 XMMMMMMF%% ... 6.2 1.3 0.0 15 16 8.3 2.1 0.0 XMMMMMMF%% ... 6.0 1.3 0.0 16 17 8.2 2.1 0.0 XMMMMMMF%% .. 5.9 1.3 0.0 17 18 7.7 2.1 0.0 XMMMMMM%%. .. 5.6 1.3 0.0 18 19 7.2 2.1 0.0 XMMMMMF%%. . 5.3 1.3 0.0 19 20 6.4 2.1 0.0 XMMMMM%%.. 4.8 1.3 0.0 20 21 5.9 2.1 0.0 XMMMM%%.. 4.5 1.3 0.0 21 22 7.3 3.7 2.4 AMMMMF%%. . 5.4 1.9 1.6 22 23 10.3 10.7 5.9 ASXMMBB %%... 6.9 6.7 3.5 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) 27-Feb-2026 BoM Space Weather Services, Sydney Australia +61-2-9213-8000