DModel/DT is calculus-based slang that meteorologists use to describe a trend in model forecasts. For example, the GFS forecast from 0600 UTC 12 March showed a less than favorable forecast for snow in the Wasatch late Saturday night and Sunday morning, with a short-weve trough over the Pacific Northwest and Utah under the influence of a short-wave ridge. Subsequent forecasts, however, have pushed the short-wave trough further east and sagged the storm-track southward, resulting in snow over the Wasatch late Saturday night and Sunday morning. This model trend is illustrated in the DModel/DT loop below, which is based on 0600 UTC initialized GFS forecasts from the past four days all verifying at 1200 UTC 17 March (Sunday). Note how each successive forecast produces more precipitation over northern Utah.