Extended Forecast
Valid: Thu 24 Oct 2024 06:00 to Fri 25 Oct 2024 06:00 UTC
Issued: Tue 22 Oct 2024 22:08
Forecaster: TUSCHY

A level 1 was issued acrosspsrts of W-CNTRL Mediterranean mainly for heavy to excesssive rain and an isolated tornado/severe gust risk.

SYNOPSIS

There is not much change on the synoptic stage with ongoing ridging atop the Ioanian Sea, another building rige over CNTRL Europe towards Scandinavia and with a broad trough over/just W of Europe. A progressive upper trough shifts into the Bay of Biscay during the forecast and pushes the meandering German cut-off to the NE.

A structuring warm front over the W Mediterranean serves as main focus for DMC activity.

DISCUSSION

... W into CNTRL Mediterranean ...

Constant pressure fall over France/the Bay of Biscay causes a broad belt of S/SE-erly BL winds atop the W Mediterranean, also driven by the anticyclone to the NE. This creates an extensive area with modest BL moisture N of Algeria/Tunisia towards Sardinia. As mid-level lapse rates increase a bit from the S, MUCAPE pushes into the 1000-2000 J/kg range with peak values SW of Sardinia.

A cyclonic SW-erly flow regime exists atop the W Mediterranean. NE-ward travelling short waves cross a SW-NE aligned region with enhanced LL confluence, so CI is forecast. Highlighting any foci regarding DMC activity is hard to do as CI is also driven on the mesoscale (e.g. local convergence zones, coastal fronts etc.).

A broad level 1 was issued to encompass the general area, where clustering convection/slow moving storms are forecast. Mesoscale dynamics probably steer any localized extreme rainfall events, with the risk extending all the way into the Golf of Genoa (where a potential serious multi-day rainfall risk evolves beyond the SWODY 2). Numerous potential outcomes are possible for a few spots with final rainfall amounts in excess of 100 l/qm/24h within the level 1 area including a flash flood risk.

Tail-end storms or more discrete activity also adds an isolated tornado and severe gust risk, especially in case of some cold pool driven activity (as some drier air exists in the 700-800 hPa layer along the confluence zone).