Weerwoord | Re: Onweersbuien vandaag lokale low topped SC's mogelijk?

Set up leent zich gezien de shearwaarden voor delen van de Benelux voor roterende onweersbuien. Zwaartepunt zou volgens Estofex.org boven Duitsland liggen. Ook een tornado wordt met name daar niet uitgesloten. Een enigszins low cape/ high shear situatie? Groetjes, Wilco

ziet er pittig uit idd.

A deep trough approaches the region from west with short-wave troughs moving on its forward flank towards northeast. Synoptic-scale lift is forecast across the area in the late morning to afternoon hours with the strongest lift over Denmark and Norway. Closer to the surface, a diffuse cold front will translate east. No strong signal in the low-level convergence is noted. Thus, no widespread mesoscale lift along the front is expected with the most likely coverage being (widely) scattered storms. Given modest low-level moisture and mid-tropospheric lapse rates, MLCAPE will stay mostly between 200 and 600 J/kg. Across central to northeastern Germany, steep low level lapse rates are forecast. Storms will be mostly low-topped with EL increasing towards the afternoon and west as the mid-tropospheric temperature drops with the arrival of the trough.

Strong vertical wind shear is forecast across the whole region, with 0-3 km bulk shear between 15 and 20 m/s and 0-1 km bulk shear up to 15 m/s locally. Especially over NW and N Germany, high-resolution models pick out mesoscale areas of strongly curved hodographs with large fraction of streamwise vorticity in the inflow to the storm and 0-500 m SRH exceeding 100 m2/s2. Combined with low LCLs and steep low-level lapse rates, there will be an enhanced threat of tornadoes with low-topped supercells and short linear segments. Given impressive kinematic setup, some of the tornadoes could become strong. Besides the tornadoes, severe wind gusts may occur in the downdrafts of the supercells.

Level 2 was introduced for the area, where several waves of low-topped supercells/linear segments are possible and high-res models give the highest low-level SRH values. A primary failure mode for this scenario would be that the lapse rates in the lower troposphere are worse than forecast, yielding lower CAPE, weaker lower tropospheric updrafts and thus also potential for vertical stretching of the ambient vorticity.