SWS GRAFEX HF FREQUENCY PREDICTIONS ADDRESS NO. 1234 =============================================================================== Circuit: Karratha Perth Date: 25 March, 2026 T-index: 70 Bearings: 184 5 Distance: 1251 km First Mode |--------F r e q u e n c y (MHz)---------| Second Mode 1F 18-23 1E 5 1 5 10 15 20 25 30 35 40 2F 37-43 2E 14 UT OWF EMUF ALF |...|....| ....|....| ....|....| ....|....| OWF EMUF ALF UT 00 12.6 12.0 6.3 ASSXMMM BB%%%... 8.6 7.4 3.8 00 01 13.8 13.6 7.0 SSXXMM MBB%%%... 9.2 8.4 4.2 01 02 14.3 14.6 7.4 ASSXMM MBBB%%%... 9.5 9.0 4.5 02 03 14.6 15.2 7.6 ASSXXM MBBBP%%... 9.8 9.4 4.6 03 04 14.7 15.4 7.7 ASSXXM MMBBP%%... . 10.1 9.6 4.7 04 05 14.8 15.3 7.7 ASSXXM MMBBP%%... . 10.2 9.5 4.7 05 06 14.3 14.9 7.5 ASSXXM MMBB%%%%.. 9.9 9.2 4.6 06 07 13.9 14.1 7.2 SSSXMM MMBP%%%... 9.5 8.8 4.4 07 08 13.7 12.9 6.6 ASSXMMM MBF%%%%... 9.3 8.0 4.0 08 09 13.6 10.8 5.8 ASXMMMM MFF%%%%... 9.1 6.7 3.5 09 10 11.8 6.2 3.6 SMMMMMMM F%%%%%... 7.9 3.9 2.2 10 11 9.7 2.0 0.0 XMMMMMMMM% %%%.... 6.7 1.2 0.0 11 12 8.1 2.0 0.0 XMMMMMMM%% %... 5.9 1.2 0.0 12 13 7.3 2.0 0.0 XMMMMMM%%% ... 5.3 1.2 0.0 13 14 6.9 2.0 0.0 XMMMMM%%%. .. 5.1 1.2 0.0 14 15 7.0 2.0 0.0 XMMMMM%%%. . 5.2 1.2 0.0 15 16 6.9 2.0 0.0 XMMMMM%%%. . 5.1 1.2 0.0 16 17 6.8 2.0 0.0 XMMMMM%%%. . 5.0 1.2 0.0 17 18 6.5 2.0 0.0 XMMMMM%%.. 4.8 1.2 0.0 18 19 6.2 2.0 0.0 XMMMMM%%.. 4.7 1.2 0.0 19 20 5.5 2.0 0.0 XMMMM%%.. 4.1 1.2 0.0 20 21 5.0 2.0 0.0 XMMMM%.. 3.8 1.2 0.0 21 22 6.2 2.0 0.0 XMMMMF%%. 4.7 1.2 0.0 22 23 10.2 9.3 5.1 SSMMMBF %%.. 6.9 5.7 3.1 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) 25-Mar-2026 BoM Space Weather Services, Sydney Australia +61-2-9213-8000