Storm Forecast
Valid: Thu 30 Mar 2017 06:00 to Fri 31 Mar 2017 06:00 UTC
Issued: Wed 29 Mar 2017 21:18
Forecaster: GATZEN

SYNOPSIS

A short-wave trough rotates around an east-European long-wave trough, causing cold air advection in its wake to expand into most of eastern Europe. Ahead of dry air spreading south, some moisture is present during the day from Romania and Bulgaria into Turkey and the Aegean Sea and Greece region. Weak CAPE evolves during the day as mid-level are rather cold. Some thunderstorms are expected to develop, focussed across Romania and Bulgaria as well as southern Turkey. Further storms can form over the east Mediterranean colse to the base of an upper trough that provides low-level convergence and steep lapse rates. Given weak vertical wind shear, most of this activity remains unorganized and severe weather is not forecast.

DISCUSSION

North-western Spain and northern Portugal, Irland, Wales, and western England

Over western Europe, another long-wave trough approaches from the west. A negatively tilted vort-max rotates around its base and crosses north-western Iberia in the evening hours. Downstream, a weaker short-wave trough moves over Ireland during the day.

With the south-westerly flow, steep mid-level lapse rates are advected towards France and England. These lapse rates overlap with quite substantial low-level moisture, however, strong CIN is expected over most places and initiation is not likely. Best chances exist with the short-wave troughs passing over the Bay of Biscay in the evening and night hours and over the British Isles earlier in the day. This might initiate scattered storms over north-western Iberia as indicated by latest GFS model output. These storms may spread north-east and will become quickly elevated over the Bay of Biscay and may weaken during the night hours. Some more storms are not ruled out further north, especially Ireland and western England and Wales.

Storms that form over Iberia and the British Isles can profit from strong vertical wind shear. Some supercells and multicells are not ruled out. These may be capable of producing severe wind gusts and tornadoes. Large hail is not ruled out. Threat is limited though given the weak low-level buoyancy. Therefore, no threat level was issued.