## 6 Analysis of RAMS-ISAC Simulations
The warm core caused by the release of the latent heat of the evolving TLC extends from 1 km to 10 km height (with 1.5 K anomaly between 2 and 5 km height), showing a deep vertical extension of Numa. Relative humidity is lower in the warm core region. It is higher below 2 km height and in the outer regions of the TLC, indicating (a) low-level moisture convergence and (b) moisture redistribution by the convection. Figure 16: (**a**) Vertical cross-section of temperature anomaly (filled contour) and relative humidity (contours from 30% to 100% every 10%) on 17 November at 19:00 UTC. The cross-section along 39.2 \({}^{\circ}\)N latitude is shown between 15\({}^{\circ}\)E and 20\({}^{\circ}\)E for clarity. (**b**) As in (**a**) for the meridional wind velocity (contours from -20 m/s to 14 m/s every 2 m/s; black contours are positive values, blue contours are negative values, magenta contours is 0) and equivalent potential temperature (filled contours). Figure 15: (**a**) RAMS-ISAC winds on 17 November at 19:00 UTC at z=24 m above the surface. (**b**) Winds retrieved from ASCAT onboard MetOpA (orbit 57497) overpass on 17 November at 19:09 UTC. The product optimized for coastal regions is shown here. Figure 16b shows the vertical cross-section, at the same latitude of Figure 16a of the equivalent potential temperature and of the meridional wind speed. Typical features of TLC are apparent as the state of nearly-moist neutrality of ascending air parcels, the limited horizontal extension of the TLC, the axisymmetric shape, the windless region in proximity of cyclone center (the TLC calm eye), and the low vertical wind shear up 6 km height [5; 7; 13]. The results of Figure 16a,b indicate that the so-called Wind Induced Surface Heat Exchange (WHISHE [56; 57]) may play an important role in Numa TLC phase maintenance. The Implementation of DPR (Dual Frequency Precipitation Radar) Reflectivity Observation in RAMS-3 Dvar  
In this section we show the implementation of DPR 3D reflectivity field as an observation in the RAMS-ISAC data assimilation scheme. The RAMS-3 DVar assimilation scheme [39] modified to assimilate reflectivity factor observed by ground radars [58] is used for this purpose. The background is given by a short-term forecast of the RAMS-ISAC. More specifically, since the DPR observation is available at 13:49 UTC on 16 November, we use the background at 14:00 UTC neglecting the time difference between the DPR observation and the RAMS-ISAC background. The DPR reflectivity is sampled at seven vertical levels from 2000 m to 8000 m to match the model vertical bins, and is assimilated following [PERSON] et al. [59]. Hereafter, the simulation with no DPR assimilation is referred to as CTRL, while the simulation with DPR assimilation is referred to as ANL. Figure 17a shows the difference between ANL and CTRL forecast of the relative humidity (RH) field at 14:00 UTC, at 3172 m in the terrain following coordinate system used by RAMS-ISAC. There are several areas of the domain where the assimilation increases the relative humidity of the model (RH difference up to 30%). For comparison, Figure 17b shows the DPR reflectivity at 3000 m at 13:49 UTC, quantifying the impact of the DPR reflectivity assimilation on the RH field. The largest impact on the forecast is introduced south of 36\({}^{\circ}\)N, in correspondence of the main \"comma\"-shaped rain band observed by DPR (see Figure 10b). The RH perturbation is significant and, once assimilated into the model, it may determine saturation and precipitation where/when introduced. Other perturbations to the RH field are given in Northeastern Sicily and in Central-Eastern Italy. As stated above, the DPR data are assimilated at 14:00 UTC on 16 November. As shown in the previous section, the forecast starting on 16 November at 12:00 UTC missed the precipitation over Southern Apulia 24-48 h later (between 17 November at 12:00 UTC and 18 November at 12:00 UTC).