SWS GRAFEX HF FREQUENCY PREDICTIONS ADDRESS NO. 1234 =============================================================================== Circuit: Karratha Perth Date: 20 March, 2026 T-index: 75 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 37-44 2E 14 UT OWF EMUF ALF |...|....| ....|....| ....|....| ....|....| OWF EMUF ALF UT 00 12.6 12.2 6.4 ASSXMMM BB%%%... 8.5 7.6 3.9 00 01 13.8 13.8 7.1 SSSXMM MBB%%%... 9.2 8.5 4.3 01 02 14.2 14.7 7.5 ASSXXM MBBB%%%... 9.5 9.1 4.5 02 03 14.4 15.3 7.7 ASSXXM MBBBP%%... 9.8 9.5 4.7 03 04 14.6 15.6 7.8 ASSXXM MMBBP%%... 10.1 9.7 4.8 04 05 14.7 15.5 7.8 ASSXXM MMBBP%%... . 10.2 9.6 4.7 05 06 14.3 15.1 7.6 ASSXXM MMBBP%%... 9.9 9.4 4.6 06 07 13.8 14.3 7.3 SSSXMM MMBP%%%... 9.5 8.9 4.4 07 08 13.6 13.0 6.8 SSXXMM MBB%%%%... 9.3 8.1 4.1 08 09 13.6 11.1 5.9 ASXMMMM MFF%%%%... 9.1 6.9 3.6 09 10 11.9 6.8 3.9 SXMMMMMM F%%%%%... 8.0 4.2 2.4 10 11 10.0 2.0 0.0 XMMMMMMMM% %%%%... 6.9 1.2 0.0 11 12 8.4 2.0 0.0 XMMMMMMM%% %... 6.1 1.2 0.0 12 13 7.6 2.0 0.0 XMMMMMM%%% ... 5.5 1.2 0.0 13 14 7.2 2.0 0.0 XMMMMMM%%. .. 5.3 1.2 0.0 14 15 7.3 2.0 0.0 XMMMMMF%%. .. 5.3 1.2 0.0 15 16 7.1 2.0 0.0 XMMMMMF%%. . 5.2 1.2 0.0 16 17 7.1 2.0 0.0 XMMMMMF%%. . 5.1 1.2 0.0 17 18 6.7 2.0 0.0 XMMMMM%%.. . 4.9 1.2 0.0 18 19 6.4 2.0 0.0 XMMMMM%%.. 4.8 1.2 0.0 19 20 5.6 2.0 0.0 XMMMM%%.. 4.2 1.2 0.0 20 21 5.1 2.0 0.0 XMMMM%.. 3.9 1.2 0.0 21 22 6.5 2.0 0.0 XMMMMM%%.. 4.8 1.2 0.0 22 23 10.4 9.6 5.2 SSMMMBF %%... 7.0 5.9 3.2 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) 20-Mar-2026 BoM Space Weather Services, Sydney Australia +61-2-9213-8000