SWS GRAFEX HF FREQUENCY PREDICTIONS ADDRESS NO. 1234 =============================================================================== Circuit: Geraldton Perth Date: 31 July, 2026 T-index: 90 Bearings: 162 341 Distance: 373 km First Mode |--------F r e q u e n c y (MHz)---------| Second Mode 1F 52-57 1E 24 1 5 10 15 20 25 30 35 40 UT OWF EMUF ALF |...|....| ....|....| ....|....| ....|....| OWF EMUF ALF UT 00 6.8 3.9 2.5 AFFF%.. 00 01 7.9 4.8 3.0 ABFFF%%. 01 02 8.4 5.3 3.3 BBFFF%. . 02 03 8.7 5.6 3.4 BBFFF%. . 03 04 8.7 5.8 3.5 ABFFF%. . 04 05 8.6 5.7 3.4 BBFFF%. . 05 06 8.6 5.5 3.4 BBFFF%. . 06 07 8.5 5.2 3.2 BBFFF%. . 07 08 8.3 4.6 2.9 ABFFFF%. . 08 09 7.9 3.4 2.2 BFFFF%%. 09 10 6.6 0.8 0.0 FFFFFF%.. 10 11 5.2 0.8 0.0 FFFFF%.. 11 12 4.4 0.8 0.0 FFFF%.. 12 13 4.0 0.8 0.0 FFF%.. 13 14 3.7 0.8 0.0 FFF%.. 14 15 3.6 0.8 0.0 FFF%. 15 16 3.5 0.8 0.0 FFF%. 16 17 3.5 0.8 0.0 FFF%. 17 18 3.4 0.8 0.0 FFF%. 18 19 3.2 0.8 0.0 FFF%. 19 20 3.1 0.8 0.0 FFF%. 20 21 3.0 0.8 0.0 FF%%. 21 22 3.1 0.8 0.0 FFF. 22 23 4.8 0.8 0.0 FFFF%. 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-Jul-2026 BoM Space Weather Services, Sydney Australia +61-2-9213-8000