We propose deriving wireless simulation models from experimental traces of radio signal strength. Because experimental traces have holes due to packet losses, we explore two algorithms for filling the gaps in lossy experimental traces. Using completed traces, we apply the closest-t pattern matching (CPM) algorithm, originally designed for modeling external interference, to model signal strength. We compare the observed link behavior using our models with that of the experimental packet trace. Our approach results in more accurate packet reception ratios than current simulation methods, reducing the absolute error in PRR by up to about 30%. We also find that using CPM for signal strength improves simulation of packet burstiness, reducing the Kantorovich-Wasserstein (KW) distance of conditional packet delivery functions (CPDFs) by a factor of about 3 for intermediate links. These improvements give TOSSIM, a standard sensor network simulator, a better capability to capture real-world dynamics and edge conditions that protocol designers typically must wait until deployment to detect.