Convective Outlook - S. UK - Sun June 7th

[martinastro]

From Tony Gilbert



There is a slight risk of scattered thunderstorms central south & SE UK 06Z-21Z Sun 7th June 2009

Marginal risk of brief funnel clouds

ATM a rather low risk outlook with restrictions. Unseasonally deep upper troughing edges NE with low pressure building at surface. Initial occluded front pushes NE from early Sunday morning bringing heavy rain to many areas. It is expected that a surface trough will develop within an unstable environment in the wake of the initial front bringing further scattered showers some of which could become thundery in nature. Upper shear looks minimal and moisture somewhat limited to the SE. Though the circulation within the low is stacked vertically and is open at mid levels increasing PVA lift. Convergence at surface with a layer of dry air at mid levels may create a marginal environment for CZ tornado development.

Similar outlooks have seen CAPEs rapidly diminish as a large cold pool spreads out at surface and upper cloud remains overhead within the confines of the lows circulation. So all in all some risk here but the said restrictions may win the day!

Based on the current model output the best scope for storms looks to be around Somerset during the afternoon where the best moisture pools and upper dry air combine.

Prob worth an update in the morning!

[martinastro]

Storm Forecast Issued: 2009-06-07 21:33:00
Valid: 2009-06-07 00:00:00 - 2009-06-07 23:59:00

Regions Affected
East Anglia, Southeast England, Central Southern England, West Country, South & East Midlands ( Wales, SW England, N England, Northern Ireland and the remaining Midlands are all included in the WATCH

Synopsis
A stationary occlusion continues to affect the UK during Sunday, continuing with the high rainfall totals theme. During the early hours of the morning, steady and heavy rainfall will continue to fall across parts of southern England and south Wales. Showers, heavy and perhaps thundery may clip parts of the Southwest at times. During the day the band of heavy rain will drift slowly northwards across the Midlands and into southern parts of Northern England later in the day, before clearing into the North Sea. In it's wake, scattered showers and thunderstorms are forecast to develop, particularly during the afternoon and first part of the evening. Torrential downpours may accompany any showers, and hail is also quite likely. Conditions for funnels and tornadoes are too marginal with the current available data - this will require close monitoring during Sunday. Showers will be fairly slow moving, accompanied by gusty winds at times. Any showers and thunderstorms are expected to decrease slowly during the evening. Scattered showers are expected to develop over Scotland, Ireland and Northern Ireland, but these currently have a low risk of thundery activity.