Mesoscale Discussion

Mesoscale Discussion
Valid: Sun 27 Sep 2020 16:00 to Mon 28 Sep 2020 00:00 UTC
Issued: Sun 27 Sep 2020 16:24
Forecaster: PUCIK

...Severe wind gust and tornado threat may increase over the highlighted area in the next couple of hours...

Satellite imagery reveals a line of thunderstorms currently impacting south-central Italy. The line of storms has formed ahead of a sharp mid to uppper tropospheric trough that will rapidly translate towards the Adriatic Sea. 12 UTC Pratica di Mare sounding has sampled the vertical wind profile near the convective line, featuring 0-1 km bulk shear over 20 m/s with significant hodograph curvature.

Models simulate vertical wind profiles of similar magnitude (with 0-1 km bulk shear exceeding 15 m/s and SRH between 200 and 300 m2/s2 in the 0-1 km layer) spreading towards the eastern Adriatics coastline. Models also simulate development of several hundreds of J/kg of SBCAPE as the moisture is rapidly advected northward from the Ionian Sea. This is the most questionable point of the forecast given that the current dewpoint readings of 11 - 13 deg C over the area compared to the model forecasts of 14 - 16 deg C for 15 UTC. Thus, it is uncertain whether nonzero SBCAPE develops ahead of the trough. Should the moisture content reach the levels forecast by models, storms will pose distinct threat of tornadoes and severe wind gusts.

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