Tropospheric Ducting Status - Southeastern Pennsylvania

This page tracks tropospheric ducting conditions for the 900 MHz band in Southeastern Pennsylvania. Scores are derived entirely from atmospheric modeling (data from Open-Meteo): the vertical refractivity gradient is sampled at the QTH and at eight compass bearings out to 100 miles, and a duct is scored by how sharply the M-unit profile inverts and at what altitude. A high score means the atmosphere is shaped to trap and carry 900 MHz signals well past the normal horizon — it is a forecast of propagation, not a measurement of it. All charts show a rolling 24 hours. More info - How it works

Score	Label	Meaning
0.0 – 0.9	Negligible	Standard propagation only
1.0 – 2.9	Weak	Mild super-refraction; slight range extension possible
3.0 – 4.9	Moderate	Ducting layer detected; some path enhancement likely
5.0 – 6.9	Strong	Well-developed duct; good conditions for extended paths
7.0 – 10.0	Excellent	Exceptional ducting; significant range extension expected