SWS GRAFEX HF FREQUENCY PREDICTIONS ADDRESS NO. 1234 =============================================================================== Circuit: Karratha Perth Date: 18 December, 2025 T-index: 60 Bearings: 184 5 Distance: 1251 km First Mode |--------F r e q u e n c y (MHz)---------| Second Mode 1F 19-28 1E 5 1 5 10 15 20 25 30 35 40 2F 37-49 2E 14 UT OWF EMUF ALF |...|....| ....|....| ....|....| ....|....| OWF EMUF ALF UT 00 9.7 13.1 6.7 SSXXBP PEE. 6.3 8.2 4.1 00 01 10.6 14.2 7.2 SSXXBB PPEE. 6.7 8.9 4.4 01 02 11.2 15.0 7.5 ASSXXB BPPEE 7.1 9.4 4.6 02 03 11.5 15.5 7.7 ASSXXB BPPEE. 7.6 9.7 4.7 03 04 11.7 15.7 7.8 ASSXXB BPPPE.. 7.9 9.8 4.7 04 05 11.6 15.6 7.8 ASSXXM BPPPE.. 8.1 9.7 4.7 05 06 11.7 15.3 7.7 ASSXXM BPPPP... 8.1 9.5 4.6 06 07 11.6 14.6 7.4 ASSXXM BPPP%... 7.9 9.1 4.5 07 08 11.2 13.7 7.0 SSXXMM BPP%... 7.8 8.6 4.2 08 09 11.0 12.3 6.4 ASSXMMB PP%%... 7.7 7.6 3.9 09 10 10.2 10.1 5.4 SSXMMMB %%%... 7.3 6.2 3.3 10 11 10.0 4.3 2.7 MMMMMMM% %%%... 7.1 0.0 2.1 11 12 9.4 1.9 0.0 XMMMMMMMM% %%... 6.8 1.2 0.0 12 13 8.8 1.9 0.0 XMMMMMMM%% %... 6.4 1.2 0.0 13 14 8.6 1.9 0.0 XMMMMMMF%% %.. 6.1 1.2 0.0 14 15 8.7 1.9 0.0 XMMMMMMF%% %.. 6.1 1.2 0.0 15 16 8.5 1.9 0.0 XMMMMMMF%% %.. 6.0 1.2 0.0 16 17 7.9 1.9 0.0 XMMMMMM%%% .. 5.6 1.2 0.0 17 18 7.5 1.9 0.0 XMMMMMF%%. .. 5.4 1.2 0.0 18 19 7.2 1.9 0.0 XMMMMMF%.. . 5.1 1.2 0.0 19 20 6.6 1.9 0.0 XMMMMF%%.. 4.6 1.2 0.0 20 21 6.5 1.9 0.0 XMMMMF%... 4.5 1.2 0.0 21 22 7.6 8.4 4.6 ASXMMP%. .. 5.4 5.1 2.9 22 23 8.4 11.3 6.0 ASXXBPP P.. 5.9 7.1 3.6 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-Dec-2025 BoM Space Weather Services, Sydney Australia +61-2-9213-8000