Storm & Convective Forecast
Issued 2016-10-16 08:55:53
Valid: 16/10/2016 0600z to 17/10/2016 0600
CONVECTIVE / STORM FORECAST - SUN 16TH OCTOBER 2016
Upper and collocated low will drift N across western Ireland on Sunday, associated wrap around occluded fronts spreading out north and east across the UK bringing bands of heavy showers or longer spells of rain with isolated thunder.
... EIRE, N. IRELAND, ENGLAND and WALES ...
Strongest forcing for ascent and steepest lapse rates will be towards the west on Sunday closest to the upper low drifting north across Wern EIRE where stronger vorticity wrapping around the low and coldest mid-level temps are present. Frontal system bringing heavy rain north this morning will produce some isolated embedded thunder and lightning towards western areas, also a small risk of localised flooding - particularly NW UK including N. Ireland. Scattered heavy showers following on across western areas may also produce thunder and lightning, hail and gusty winds. Some strong convection is possible over warm SSTs beneath cold air aloft, with potential for organisation of isolated storms, given 30-40 knts of deep layer shear. Strong upper winds and dry air intrained into to stronger cells may bring isolated strong convective wind gusts (30-40knts) to the surface and an isolated weak tornado can't be ruled out with stronger cells where backing of winds is enhanced ahead of troughs rotating around the upper low to the west. Overall, risk of severe weather is low, so have not issued a categorical severe risk.
Key - what do the risk levels mean?
Thunderstorms - Severe thunderstorms unlikely to occur, slight risk of hail, gusting winds and localised flooding.
Slight Risk - A slight risk of severe convective weather exists. Hail >2.0cm diameter, wind gusts exceeding 50mph or 5-10% risk of a tornado within 50 miles of a point, or > 30% risk of localised flooding.
Moderate Risk - A moderate risk of severe convective weather exists. Hail 4-5cm in diameter, or wind gusts of 60-70mph, or a 10-15% chance of a tornado within 50 miles of a point, or >50% risk of localised flooding.
High Risk - A high risk of severe convective weather exists. Rarely, if ever used on the UK. Hail >5cm, or wind gusts in excess of 80mph, or >20% risk of a tornado within 50 miles of a point, or >70% risk of localised flooding.