SWS GRAFEX HF FREQUENCY PREDICTIONS ADDRESS NO. 1234 =============================================================================== Circuit: Karratha Perth Date: 28 December, 2025 T-index: 115 Bearings: 184 5 Distance: 1251 km First Mode |--------F r e q u e n c y (MHz)---------| Second Mode 1F 19-30 1E 5 1 5 10 15 20 25 30 35 40 2F 38-51 2E 14 UT OWF EMUF ALF |...|....| ....|....| ....|....| ....|....| OWF EMUF ALF UT 00 10.3 13.9 7.4 ASSXMB PPE... 7.4 8.7 4.5 00 01 11.2 15.1 7.9 ASSXXB BPPEE. 7.8 9.4 4.8 01 02 11.9 15.9 8.3 ASSSXM BPPPE.. 8.3 9.9 5.0 02 03 12.2 16.5 8.5 SSSXX BBPPEE. 8.7 10.2 5.1 03 04 12.4 16.7 8.6 SSSXX MBPPPE.. 8.9 10.4 5.2 04 05 12.6 16.6 8.6 SSSXX MBPPPE.. 9.1 10.3 5.2 05 06 12.4 16.2 8.4 SSSXX MBPPPE.. 8.9 10.1 5.1 06 07 12.0 15.6 8.1 ASSSXM BPPPP... 8.6 9.7 4.9 07 08 11.6 14.5 7.7 ASSXXM BPPP... 8.4 9.1 4.6 08 09 11.4 13.0 7.0 SSXXMM BPP%... 8.3 8.1 4.3 09 10 11.2 10.7 5.9 ASXMMMM F%%%.. 8.1 6.5 3.7 10 11 11.1 4.5 2.9 MMMMMMMF F%%... 8.0 0.0 2.3 11 12 10.6 2.2 0.0 XMMMMMMMMF %%%.. 7.9 1.4 0.0 12 13 10.4 2.2 0.0 XMMMMMMMMF %%... 7.6 1.4 0.0 13 14 9.9 2.2 0.0 XMMMMMMMM% %%.. 7.3 1.4 0.0 14 15 9.9 2.2 0.0 XMMMMMMMF% %%.. 7.1 1.4 0.0 15 16 9.8 2.2 0.0 XMMMMMMMF% %%.. 6.9 1.4 0.0 16 17 9.3 2.2 0.0 XMMMMMMMF% %.. 6.6 1.4 0.0 17 18 8.3 2.2 0.0 XMMMMMMF%% .. 6.1 1.4 0.0 18 19 7.8 2.2 0.0 XMMMMMM%%% .. 5.6 1.4 0.0 19 20 7.0 2.2 0.0 XMMMMM%%%. . 5.2 1.4 0.0 20 21 6.8 2.2 0.0 XMMMMM%%%. 5.2 1.4 0.0 21 22 8.3 8.9 5.1 SSMMB%% ... 6.1 5.4 3.2 22 23 9.8 12.0 6.6 ASSXMBP PP... 7.0 7.5 4.0 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) 28-Dec-2025 BoM Space Weather Services, Sydney Australia +61-2-9213-8000