Formation of a coastal barrier jet in the Gulf of Mexico due to the interaction of cold fronts with theSierraMadreOriental mountain range

Abstract

The passage of three cold fronts (CFs) over the Gulf of Mexico was simulated with the Weather Research and Forecasting model to study the mechanisms associated with the formation of a jet parallel to the Sierra Madre Oriental (SMOr) mountain range near the port of Veracruz. Dew‐point temperature (Td= 20 °C) and available convective potential energy best simulated the horizontal propagation of the intenseCFsover the Gulf, and equivalent potential temperature helped identify the vertical position of the fronts. Additional simulations with reduced topography showed that mountain heights exceeding 2.5 km, where theSMOris closest to the coast, were crucial for the formation of a coastal barrier jet. The Froude number (Fr < 1) and the ageostrophic component of the wind at low levels were used to identify the formation of the jet; the Rossby radius of deformation determined its horizontal extent which was 81 km into the Gulf of Mexico in agreement with scatterometer winds during one of theCFs. The interaction of the northeasterly winds (known as Nortes) with the topography produced a blocking effect resulting in a stable region of cold air, a rain‐shadow and a coastal barrier jet of northwesterly direction, which generated strong cold air advection and subsidence in comparison with adjacent zones. The jet region appears as a minimum in the winter precipitation climatology indicating that the barrier jet is an important intraseasonal feature. In two of the case‐studies, maximum jet velocities reached those of a tropical storm (>18 m s−1) and occurred near the surface (<1 km above mean sea level), consistent with observations and similar to other barrier jets in the world. For the first time the jet near the port of Veracruz is documented as a coastal barrier jet. TheCFsalso produced strong Tehuano gap winds.