SWS GRAFEX HF FREQUENCY PREDICTIONS ADDRESS NO. 1234 =============================================================================== Circuit: Karratha Perth Date: 18 March, 2026 T-index: 90 Bearings: 184 5 Distance: 1251 km First Mode |--------F r e q u e n c y (MHz)---------| Second Mode 1F 19-24 1E 5 1 5 10 15 20 25 30 35 40 2F 37-45 2E 14 UT OWF EMUF ALF |...|....| ....|....| ....|....| ....|....| OWF EMUF ALF UT 00 13.5 12.5 6.6 ASSXMMM BBF%%%.. 9.1 7.7 4.0 00 01 14.7 14.0 7.3 SSSXMM MBBB%%%... 9.8 8.7 4.4 01 02 15.1 15.0 7.7 ASSXXM MMBBB%%%.. 10.1 9.3 4.7 02 03 15.1 15.6 8.0 ASSXXM MMBBB%%%.. . 10.4 9.7 4.8 03 04 15.2 15.8 8.1 ASSSXM MMBBB%%%.. . 10.6 9.8 4.9 04 05 15.4 15.8 8.0 ASSXXM MMBBB%%%.. . 10.8 9.8 4.9 05 06 15.1 15.3 7.8 ASSXXM MMBBB%%%.. . 10.6 9.5 4.8 06 07 14.7 14.6 7.5 ASSXMM MMBB%%%%.. 10.2 9.0 4.5 07 08 14.6 13.3 7.0 SSXXMM MMBF%%%%.. 10.0 8.3 4.2 08 09 14.6 11.3 6.1 ASSMMMM MMFF%%%%.. 9.8 7.0 3.7 09 10 12.9 7.2 4.1 ASMMMMMM MF%%%%... 8.8 4.4 2.5 10 11 11.2 2.1 0.0 XMMMMMMMMM F%%%.... 7.8 1.3 0.0 11 12 9.5 2.1 0.0 XMMMMMMMM% %%... 6.9 1.3 0.0 12 13 8.7 2.1 0.0 XMMMMMMM%% %... 6.2 1.3 0.0 13 14 8.1 2.1 0.0 XMMMMMMF%% ... 5.9 1.3 0.0 14 15 7.9 2.1 0.0 XMMMMMM%%% .. 5.8 1.3 0.0 15 16 7.7 2.1 0.0 XMMMMMM%%% .. 5.6 1.3 0.0 16 17 7.7 2.1 0.0 XMMMMMM%%. .. 5.5 1.3 0.0 17 18 7.3 2.1 0.0 XMMMMMF%%. . 5.3 1.3 0.0 18 19 6.9 2.1 0.0 XMMMMM%%%. . 5.1 1.3 0.0 19 20 6.1 2.1 0.0 XMMMMF%.. 4.5 1.3 0.0 20 21 5.6 2.1 0.0 XMMMM%%.. 4.2 1.3 0.0 21 22 7.1 2.1 0.0 XMMMMMF%.. 5.2 1.3 0.0 22 23 11.2 9.8 5.4 SSXMMBF F%%.. 7.5 6.1 3.3 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) 18-Mar-2026 BoM Space Weather Services, Sydney Australia +61-2-9213-8000