An Example of the Importance of Ship Observations

Abstract

The impact of one ship observation on the National Meteorological Center's (NMC) North Atlantic surface pressure analysis, forecast models, and various forecasts is discussed. In addition, the resources available to surface pressure analysts at NMC in determining the validity of ship observations are described. Based, primarily, on one ship observation, the analyzed central pressure of a low pressure system was deepened by 39 mb in 6 h. This dramatic change in central pressure impacted the NMC's North Atlantic High Seas forecasts, High-Level Aviation turbulence forecasts and the validity of the results of the NMC Medium Range Forecast (MRF) Model. It is suggested that the dramatic 6-h change in the analyzed central pressure of the low pressure system was most likely due to an initial underestimate of the depth of the low prior to the receipt of the specific ship observation and an overestimation of the central pressure as a result of the ship observation.