Convective Forecast for 10/09/10 & 11/09/10

3 Convective Weather Forecasts Are In Place (set over 2 days)- please see below:

Day 1 (10/09/10)
Region(s): N.Ireland, SW Scotland
Issued: 10.00, 10th September 2010
Threat(s): Thunderstorms, Hail, Funnel Clouds

The charts this morning for 21z tonight, just off the W coast of Ireland show Dewpoint temps of 12C and temps of 13C so low cloud bases along with Low, Mid and High layer clouds around along with SBCAPE of upto 700j/kg & MLCAPE upto 500j/kg with LI's of -3. An upper trough and EQL temps of -40C could mean night time lightning and with precipitable water at only 2.46mm then hail is likely. A Cz giving horizontal shear just off the coast along with DLS of 30 knots could help any cells sustain themselves along with a risk of FC's, the heaviest of the showers are expected N of N.Ireland across the sea making their way towards Scotland (according to GFS & NAE). I think something could occur but I also think it will happen over the West coast but given the fronts moving N of N.Ireland then a few embedded storms could occur out to sea amongst those heavy showers. These showers are within an unstable airmass from the remnants of hurricane Earl.

Day 2 (11/09/10)
AREA 1
Region(s): NW England
Issued: 10.00, 10th September 2010
Threat(s): Thunderstorms, Hail, Funnel Clouds, Weak Tornadoes.

With SBCAPE of 200-300j/kg MLCAPE upto 100j/kg with LI's of -1. Dewpoint temps at 14C and temps at 16C means low cloud bases. DLS of 50 knots could allow any cells to become organised and sustain themselves and LLS upto 20 knots means the odd weak funnel cloud could form and given the low cloud bases any FC's which do form also have the risk of touching down. EQL temps at -20 an upper trough, freezing level at 750hpa, and precipitable water of 2.12mm means hail is a possibility and also slight chance of lightning. Only marginal but definatley a chance of seeing a funnel cloud in the morning from the base of any updraught towers. Two forms of lift around for tommorrow as well in the way of frontal systems and orographic lifting, both could play apart and act as the 'trigger' needed to give the lift to initiate convection.

Day 2 (11/09/10)
AREA 2
Region(s): N.Ireland
Issued: 10.00, 10th September 2010
Threat(s): Thunderstorms, Hail, Funnel Clouds

A better set up is over N.Ireland where there is also a chance of storms tommorrow. The current GFS run for 15z tommorrow has the highest CAPE around the Lough with SBCAPE upto 900j/kg MLCAPE upto 500j/kg with LI's of -3. Dewpoint temps at 13C with temps at 16C. EQL temp at -15 with a freezing level between 800-750hpa, an upper trough with cool air aloft & Precipitable Water (PW) at 2.13mm means hail is likely with a risk of lightning. DLS is weak at only 20 knots but the convergence at the lough were the 'sea' breeze meets the environmental flow could help with storms becoming more organised and also a small chance in funnel formation. A few frontal systems also expected to pass the region throughout the day so these could act as the trigger for storms to develop from.