Storm Forecast
Valid: Mon 14 Sep 2020 06:00 to Tue 15 Sep 2020 06:00 UTC
Issued: Mon 14 Sep 2020 02:59
Forecaster: VAN DER VELDE

A level 1 was issued across Iberian Peninsula mainly for large hail.
A level 1 was issued across Malta and E Tunisia for excessive rainfall and tornado chances.

DISCUSSION

A blocking high over central Europe ensures calm conditions over a wide area, with northwesterly flow across Scandinavia and W Russia and only minor influence of low pressure systems over the Iberian Peninsula and southern Mediterranean basin.

...Portugal, Spain, N Morocco...

An Atlantic trough causes the flow of warm but somewhat dry air with steep lapse rates northward over Iberian Peninsula. Models depict up to 500 J/kg CAPE across the western half and up to 1200 J/kg in the south. Vertical shear reaches 10-15 m/s at 0-3 and 0-6 km. A clear PV anomaly causes lifting. Storm development will likely be quite widespread and some large hail is likely, as are isolated severe wind gusts, thanks to high LCL (>2000m). Around the Alboran Sea the convection will likely be elevated above a stable layer, preventing the strong low-level shear there to be effective.

...Malta, Tunisia...

Humid and slow-moving air mass is found across the western Libyan Sea where a low causes convergent easterly flow to trigger storms with a high potential for excessive rainfall, most of it over sea, but some tens of mm of rain may fall in Malta and eastern Tunisia. Waterspout-type tornadoes are also likely.