Convective Outlook - Ireland & UK - Sat June 27th

[martinastro]

Storm Forecast Issued: 2009-06-26 19:38:00
Valid: 2009-06-27 00:00:00 - 2009-06-27 23:59:00

Regions Affected
Northern Ireland, Southwest Scotland, Northern England, The Midlands, East Anglia, much of Wales (southern Scotland, southern England and much of Ireland are included in the WATCH )

Synopsis
The band of rain over north Wales at the start of this forecast, with embedded cells at times, will continue to drift northwestwards across the Irish Sea towards Northern Ireland during the early hours, but dissipating all the while. The UK is then left within a slack airflow, with High pressures to the north and south of the UK, and in a humid and very warm air mass. Daytime heating and local convergence zones will play a major part in breaking out showers and thunderstorms during the day. Due to the virtually negligible winds, the showers and storms will be very slow moving and may cause local flash flooding. Lightning, thunder and hail may accompany some of the showers, along with local gusty winds. The showers and storms are expected to decrease in coverage during the evening, but may persist until the late evening in some parts.

[martinastro]

Moderate Risk of General Tstorms NW Ireland, Southern & Central UK regions 12Z-21Z

Slight Risk of Weak Tornado Development Central South UK 12Z-18Z

Synopsis is by far superior compared with recent thundery outlooks with sharp upper break away trough forcing lift and increasing lapse rates at all levels, unlike recent outlooks. Surface convergence rather weak but will on this occasion be directly influenced by sea breeze. Upper shear remains weak but strong mid level PVA is likely within the southern most sector of troughing. In addition to this we are likely to see TRUE potential instability realised along the southern most periphery of convection. Which is also in line the best predicted confluent vector at surface.

At the very least the outlook for Saturday has more potential for significant thundery activity including localised weak tornado development than any day this week so far. Based on current model output if you live in North Dorset or Somerset then a good day to look to the sky's!!

[markt]

Thanks for the update Martin!

Yesterday afternoon saw some VERY heavy downpours here to the west of Birmingham, with some quite bad local flooding.  I had to dive into a local pub on the way home from work to get out of the rain! 

Weather gain looks interesting for us today - I've got a Summer Fair at the school I work at this lunchtime, which has had alot of work go into it in terms of planning and preparation - it's overcast here at the moment, but on this occassion we don't get any downpours, today, at least

[martinastro]

Bust forecast for NI today, didn't even get a shower or any convection at all. However, massive storm being reported by many people over London with strong inflow and possible Mesocyclone!.

Next week is looking more promising for severe thunderstorms across Britain and Ireland from Wed to Fri. Should be an interesting week ahead for those who are lucky enough to get them with a further risk of night t-storms.