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Storm Forecast
Valid: Sat 27 Aug 2011 06:00 to Sun 28 Aug 2011 06:00 UTC
Issued: Sat 27 Aug 2011 03:57
Forecaster: VAN DER VELDE / KOROSEC
A level 2 was issued for N Italy, Austria, Slovenia, across E Czech Republic and W Slovakia into central Poland mainly for large hail and severe wind gusts, and perhaps a tornado. Excessive convective rain chance exists along the south flank of the Alps.
A level 1 was issued for areas surrounding the level 2 mainly for some large hail and severe wind gusts and excessive convective rain.
A level 1 was issued for southern Scandinavia mainly for excessive convective rain, large hail, and some chance of tornadoes.
SYNOPSIS
A deep trough over western Europe now acting as a negative tilted trough with its axis crossing the central Europe during the day. At surface, a sharp cold front extends from southern Scandinavia towards the southern Alpine region. The front gets pushed eastwards and serves as a focus for robust convective activity over the highlighted areas. Cool maritime airmass overspreads western Europe and results in scattered convection.
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Forecaster: Dan
Last Updated: 23:13 Friday, 26th August 2011
Valid: 00:00 Saturday, 27th August 2011 - 23:59 Saturday, 27th August 2011
Areas Affected:
MDT: C + SW Scotland, Borders, NE England
SLGT: C + S Scotland, Northern Ireland, N England, N + E Midlands, East Anglia
Synopsis:
An upper trough becomes an upper low as it slowly migrates northeastwards towards Norway, leaving the United Kingdom in a showery rPm NWerly airmass. Local convergence will provide the greatest focus for significant convection.
Discussion:
Cold upper levels will steepen lapse rates as diurnal heating occurs, leading to several hundred J/kg CAPE. This, combined with local convergence zones and topographical uplift will result in numerous showers across many parts of the country, and thunderstorms likely across southern Scotland, northern and eastern England given ELT's as low as -50C in places. Embedded troughs and areas of PVA are likely to enhance convection and thus thunderstorm coverage across the threat areas.
There is a lack of any noteworthy DLS or LLS, and thus the severe weather threat will be limited, although given the setup a CZ-type funnel is possible. Smail hail is likely in some showers given cold air aloft, possibly >1cm over East Anglia.
It must be noted that the greatest instability will slowly migrate northwards and eastwards during the day as the upper low continues it's journey northeastwards, and thus those areas in the southern portions of the SLGT area have their best potential until mid-afternoon.
Met O Chart has it over the East of the country, but not as far South as ESTOFEX:
CAPE is patchy and gone by 15.00 Hrs:
A little patch of something around Hull?
Higher level not too bad either:
So an Eastern England possibility, maybe around the Humber later on in the morning/early afternoon?
haha. A few moderate showers forecast here, but some big dark clouds are forming just to the North of here as they head off to the SE.
