SWS GRAFEX HF FREQUENCY PREDICTIONS ADDRESS NO. 1234 =============================================================================== Circuit: Karratha Perth Date: 31 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 37-44 2E 14 UT OWF EMUF ALF |...|....| ....|....| ....|....| ....|....| OWF EMUF ALF UT 00 14.2 12.1 6.4 ASSXMMM MBFF%%%.. 9.6 7.5 3.9 00 01 15.6 13.8 7.1 SSSXMM MMBFF%%%.. . 10.4 8.5 4.3 01 02 16.2 14.8 7.6 ASSXXM MMBBFF%%%. .. 10.7 9.2 4.6 02 03 16.2 15.4 7.9 ASSXXM MMMBBF%%%. .. 11.0 9.6 4.8 03 04 16.3 15.7 8.0 ASSXXM MMMBBF%%%. .. 11.1 9.7 4.8 04 05 16.3 15.6 7.9 ASSXXM MMMBBF%%%. .. 11.3 9.7 4.8 05 06 15.8 15.1 7.7 ASSXXM MMMBB%%%%. .. 11.0 9.4 4.7 06 07 15.5 14.3 7.4 ASSXMM MMMBF%%%%. .. 10.8 8.9 4.5 07 08 15.2 13.0 6.8 SSXXMM MMBFF%%%.. . 10.5 8.1 4.1 08 09 15.1 10.9 5.9 ASXMMMM MMFFF%%%.. . 10.1 6.7 3.5 09 10 13.3 5.4 3.3 ASMMMMMMM MFF%%%%... 8.9 3.4 2.0 10 11 11.0 2.1 0.0 XMMMMMMMMM %%%%.... 7.6 1.3 0.0 11 12 9.5 2.1 0.0 XMMMMMMMF% %%... 6.8 1.3 0.0 12 13 8.4 2.1 0.0 XMMMMMMM%% %.. 6.1 1.3 0.0 13 14 7.9 2.1 0.0 XMMMMMM%%% .. 5.8 1.3 0.0 14 15 7.7 2.1 0.0 XMMMMMM%%. .. 5.6 1.3 0.0 15 16 7.5 2.1 0.0 XMMMMMM%%. .. 5.5 1.3 0.0 16 17 7.4 2.1 0.0 XMMMMMF%%. .. 5.4 1.3 0.0 17 18 7.1 2.1 0.0 XMMMMMF%%. . 5.3 1.3 0.0 18 19 6.8 2.1 0.0 XMMMMM%%.. 5.0 1.3 0.0 19 20 6.1 2.1 0.0 XMMMMM%.. 4.5 1.3 0.0 20 21 5.5 2.1 0.0 XMMMM%%.. 4.1 1.3 0.0 21 22 6.7 2.1 0.0 XMMMMM%%.. 5.0 1.3 0.0 22 23 11.3 9.2 5.1 SSMMMMF F%%.. 7.6 5.6 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) 31-Mar-2026 BoM Space Weather Services, Sydney Australia +61-2-9213-8000