SWS GRAFEX HF FREQUENCY PREDICTIONS ADDRESS NO. 1234 =============================================================================== Circuit: Perth district Date: 12 April, 2026 T-index: 75 Bearings: 0 180 Distance: 0-300 km First Mode |--------F r e q u e n c y (MHz)---------| Second Mode 1F 60-90 1E 40-90 1 5 10 15 20 25 30 35 40 ** NONE ** UT OWF EMUF ALF |...|....| ....|....| ....|....| ....|....| OWF EMUF ALF UT 00 6.7 2.5 2.2 FFFF%%. 00 01 7.4 3.0 2.5 AFFFF%%. 01 02 7.9 3.2 2.6 AFFFF%%. . 02 03 8.2 3.4 2.7 AFFFFF%. . 03 04 8.4 3.4 2.8 AFFFFF%% . 04 05 8.6 3.4 2.8 AFFFFF%% .. 05 06 8.3 3.3 2.7 AFFFFF%% .. 06 07 8.0 3.1 2.6 AFFFF%%% . 07 08 7.8 2.8 2.4 FFFFF%%. . 08 09 7.3 2.3 2.0 AFFFFF%%. 09 10 6.2 0.4 0.0 FFFFFF%%. 10 11 5.0 0.4 0.0 FFFF%%.. 11 12 4.4 0.4 0.0 FFFF%%. 12 13 4.0 0.4 0.0 FFF%%. 13 14 4.0 0.4 0.0 FFF%%. 14 15 4.0 0.4 0.0 FFF%%. 15 16 3.9 0.4 0.0 FFF%%. 16 17 3.8 0.4 0.0 FFF%.. 17 18 3.7 0.4 0.0 FFF%.. 18 19 3.6 0.4 0.0 FFF%. 19 20 3.4 0.4 0.0 FFF%. 20 21 3.2 0.4 0.0 FFF%. 21 22 3.5 0.4 0.0 FFF%. 22 23 5.1 1.7 1.6 AFFF%. 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) 12-Apr-2026 BoM Space Weather Services, Sydney Australia +61-2-9213-8000