This research attempts to investigate the coastal flow structure horizontally. The flow cases with different flow directions, including perpendicular and parallel to the shoreline directions, are selected by analyzing the New Europe Wind Atlas (NEWA) reanalysis data. After the cases are determined, high-resolution Weather Research and Forecasting Model (WRF) are performed under Yonsei University (YSU) Planetary Boundary Layer (PBL) scheme with ERA5 forcing data. The results are validated against the measurements from long-range wind scanner WindCube 400S. The validated data is analyzed for quantifying the orthogonal wind speed gradient over the study domain. As a result, the WRF, being a mesoscale modelling tool, it captures the orthogonal coastal wind speed gradients reasonably accurate within a 6km range compared with observations. Generally, WRF performs better in the alongshore flow cases, especially in the flow case 2018-10-08 when the stable condition occurs most frequently during the case. The Root Mean Square Error (RMSE) for this case is 0.9m/s. However, the simulation results lost correlations with the observational data in some epochs when the fluctuation of wind speed occurs frequently. To be concrete, during flow case 2018-12-10 when the flow direction is around 330◦ advecting onshore, the WRF simulation can predict the fluctuations correct in magnitude but with shifting in time. For the coastal wind speed gradient, WRF predicts an absolute wind speed difference of 0.5 m/s daily averaged at the typical hub-height over a 1.4km distance for the alongshore flow cases. This difference can enlarge to 1m/s or higher while the low-level jets take place. The long-range wind scanning LiDAR provides a great possibility for observing the flow condition over a wind farm sized domain. Especially for the nearshore wind farm, it compensates for lack of observations on the water.